ISRM News Journal 2024 by ISRM

NEWS J URNAL

ISRM

International Society for Rock Mechanics and Rock Engineering

ANNUAL REVIEW 2024

• PRESIDENT'S MESSAGE

• BOARD ACTIVITIES

• AWARDS REPORTS

• SECRETARY-GENERAL

• CONFERENCES

• COMMITEES

• VICE-PRESIDENTS

TECHNICAL PAPERS

• FRANKLIN LECTURE

• ROCHA MEDAL LECTURE

• JOHN HUDSON ROCK ENGINEERING AWARD

• YOUNG ROCK ENGINEER AWARD

• SCIENCE ACHIEVEMENT AWARDS

Volume 27 December 2024

The 2025 ISRM

International Symposium

EUROCK 2025

Expanding the underground space: future development of the subsurface

16-20 June 2025

Trondheim Norway

WELCOME TO TRONDHEIM

MAIN TOPICS

1. New Tools and Techniques

2. Rock Support Design

3. Rock Mass Characterization

4. Prognosis Models in Rock Tunneling

5. Fluid Flow in Rock Mass

6. Ground Investigations

7. Laboratory Testing of Rock

8. Brittle Failure

9. Rock Mass Monitoring

10. Geohazards

11. 3D modelling and Visualization

12. Rock Mass Grouting

13. Sustainability in Rock Engineering

https://eurock2025.com ngb@tekna.no

The Norwegian Group for Rock Mechanics welcomes you to Norway for EUROCK 2025, the international symposium of ISRM.

The event will take place at the Clarion Hotel & Congress in the beautiful city of Trondheim from June 16th to 20th.

The historical city of Trondheim was founded in 997 as a trading post during the Viking Age and served as the capital of Norway until 1217. Today it is the third largest city in Norway and known as the technological hub of Norway, hosting the largest university, the Norwegian University of Science and Tehnology (NTNU), as well as the Foundation for Science and Industrial Research (SINTEF), St. Olavs University Hospital and several other technologyoriented institutions.

KEYNOTE SPEAKERS

Åsa Fransson

Is it watertight? Observations and comments related to grouting of rock mass

Charlie Chunlin Li

A study of the arching effect, bond strength and rock mass failure around rock anchors

Hongwei Huang

Machine learning for safety risk assessment on Rock Tunnel Driving

Jessa Vatcher

Are we in the golden age of numerical modelling?

Marco Barla

The design of energy tunnels for a sustainable future

Mark Diedrichs

Brittle Damage in Rock Mechanics

Thomas Marcher

The challenges of "hard soil and soft rock": an inside into this material's brittle to ductile behaviour

NEWS J URNAL

ISRM

International Society for Rock Mechanics and Rock Engineering

EDITORS

PROF. SEOKWON JEON

ISRM President

sjeon@snu.ac.kr

LETTER FROM THE EDITORS

DR. JOSÉ MURALHA

LNEC, Portugal

jmuralha@lnec.pt

ISRM SECRETARY-GENERAL

DR. LUÍS LAMAS

LNEC, Portugal

secretariat@isrm.net

In Asian cultures, the 60th birthday holds significant meaning. It marks the completion of a full cycle in the Asian Zodiac, symbolizing not only a celebration of health but also the beginning of a new phase and a sense of hope. Similarly, our society, having celebrated its 60th anniversary in 2022, is embracing new changes and developments as it is going through a fresh phase of growth and innovation. These include the expansion of online activities and the construction of a digital archive, increased research and activities related to climate crisis responses, and efforts to promote diversity. We would like to express our heartfelt gratitude to all members, National Groups, Commissions, and other bodies of our society who have contributed to these changes and advancements over the past years.

The News Journal 2024 serves as a yearbook summarizing our society’s activities in the past year. Unlike previous editions, this year’s issue includes several additional features. It features a contribution from Vice President Dr. Muriel Gasc-Barbier, who gave an outstanding presentation on woman’s career development at the ARMS13 Early Career Forum. In addition to the articles that depicted the presentations of the Muller Award, the Rocha Medal and the Franklin Lecture, articles referring to the Science Achievement Award and to the Young Rock Engineer Award are included in this issue. Furthermore, it highlights the objectives of the nine new Commissions established during the current Board term, it provides a summary of the fascinating discussions from the successfully ongoing European Debate series, and it introduces the new National Groups from Morocco that has joined and Iran that has re-joined our society.

The ISRM shares information and facilitates communication among members through various channels, including the News Journal. We look forward to sharing even more valuable and engaging updates and encourage your active participation.

Lastly, the News Journal could not fail to honor the memory of the late Dr. Every Hoek - a giant in rock mechanics whose contributions have a profound and enduring impact in the progress of Rock Mechanics and Rock Engineering. This issue includes an ISRM Tribute prepared by Past-Presidents Prof. Charles Fairhurst and Prof. E.T. Brown, as well as details of the Scientific Farewell Lecture by Prof. Leandro Alejano.

Seokwon Jeon and José Muralha News Journal Editors

ISRM Sponsored Conference

LAGER 2026

An International Workshop of JTC1 and JTC3

27 April-1 May 2026

Queenstown, New Zealand

NAU MAI, HAERE MAI – WELCOME!

The New Zealand Geotechnical Society is delighted to welcome you to the First International Joint Workshop of JTC1 and JTC3 on Landslide Risk Assessment, Communication and Geo-education. We will share the latest research and develop best practice guidelines in the stunning New Zealand city of Queenstown.

Landslides are one of New Zealand’s most significant natural hazards. Since 1760 there have been at least 1,500 deaths from landslides in New Zealand. More fatalities have occurred from landslides than from earthquakes, volcanic activity and tsunami combined over the last 160 years. Queenstown is particularly vulnerable, making it an ideal venue for a conference about landslides. More than 50% of the land around the town is mapped as known landslides, with the underlying quartzofeldspathic schist very susceptible to deep seated failures. The largest failure is the Queenstown Hill Landslide, with an estimated volume of 240 M m³.

Our theme “Landslide Geo-Education and Risk” brings together the full lifecycle of landslide risk management. It encompasses the need to educate the next generation of landslide risk managers, the need to robustly understand landslide risk, and the need to communicate such risk to the public and decisionmakers so that real change is implemented. We believe that bringing together JTC1 and JTC3 to work together on landslide risk assessment, education, communication and outreach is a great opportunity to effect real change.

http://landsliderisk.nz secretary@nzgs.org

ISRM Specialed Conference

6th ICITG

A JTC2 Conference

13-16 October 2026

Graz, Austria

The 6th International Conference on Information Technology in Geo-Engineering (6th ICITG) will be an arena to discuss all topics related to the ongoing digital transformation in Geo-Engineering. Case studies of IT in Geo-Engineering, integration of digital systems (Scan2BIM, BIM2FEM, etc.), benchmark datasets, information modelling, monitoring technology and artificial intelligence are some of the focus topics of the 6th ICITG. It is organized under the auspices of the Joint Technical Committee 2 (JTC2) on “Representation of Geo-Engineering Data” of the Federation of International Geo-Engineering Societies (FedIGS).

FOCUS TOPICS

Information Technology in Geo-Engineering practice –Case Studies

Integrating digital systems: Scan2BIM, BIM2FEM, etc.

Big open benchmark datasets in Geo-Engineering

Information technology for uncertainty quantification and mitigation

SoA Machine Learning in Geo-Engineering: reinforcement learning, LLMs and more

Real Time Back Analysis

THE 2023-2027 ISRM BOARD

SEOKWON JEON KOREA

President

Prof. Seokwon Jeon

Dep. Energy Systems Engineering Seoul National University sjeon@snu.ac.kr

QIANBING ZHANG AUSTRALIA

Vice-President for Australasia

Dr. Qianbing Zhang

Director of Research Department of Civil Engineering Monash University qianbing.zhang@monash.edu

MARTIN GRENON CANADA

Vice-President for North America

Prof. Martin Grenon

Département de génie des mines, de la métallurgie et des matériaux

Faculté des sciences et de génie Université Laval magre@ulaval.ca

KIYOSHI KISHIDA

JAPAN

Vice-President at Large

Prof. Kiyoshi Kishida

Department of Urban Management

Kyoto University

kishida.kiyoshi.3r@kyoto-u.ac.jp

JANNIE

MARITZ SOUTH AFRICA

Vice-President for Africa

Dr. Jannie Maritz

Faculty of Engineering, Built Environment and Information Technology Department of Mining Engineering jannie.maritz@up.ac.za

MURIEL GASC-BARBIER FRANCE

Vice-President for Europe

Dr. Muriel Gasc-Barbier

GéoCOD / Cerema Méditerranée muriel.gasc@cerema.fr

MILORAD JOVANOVSKI NORTH MACEDONIA

Vice-President at Large

Prof. Milorad Jovanovski

University Ss.Cyril and Methodius in Skopje

Faculty of Civil Engiyneering Department for Geotechnics jovanovski@gf.ukim.edu.mk

LUÍS LAMAS PORTUGAL

Secretary-General

Dr. Luís Lamas

LNEC

llamas@isrm.net

KI-BOK MIN KOREA

Vice-President for Asia

Prof. Ki-Bok Min

Dep. of Energy Resources Engineering

Seoul National University kbmin@snu.ac.kr

ESTEBAN HORMAZABAL

CHILE

Vice-President for Latin America

Dr. Esteban Hormazabal

Managing Director & Corporate Consultant

SRK Consulting Chile ehormazabal@srk.cl

FENGSHOU ZHANG CHINA

Vice-President at Large

Dr. Fengshou Zhang

Dep. of Geotechnical Engineering

Tongji University fengshou.zhang@tongji.edu.cn

PRESIDENT'S MESSAGE

Dear Colleagues,

It is a pleasure to greet you and to share an overview of ISRM activities carried out in 2024. With the commencement of the new Board’s term, various initiatives were planned and implemented. While there are areas that require further progress, I would like to provide a brief summary of the key activities undertaken.

In 2024, Morocco and Iran joined ISRM as new National Groups. The National Group of Morroco, represented by the Moroccan Committee for Soil Mechanics and Geotechnics, is the fourth member from the Africa Region. In October, they hosted the National Geotechnical Symposium in Marrakech, where ISRM Vice President Dr. Muriel Gasc attended as an official representative. Dr. Gasc congratulated them on joining the ISRM and delivered a keynote lecture. We also warmly welcome the rejoining of the Iranian Society for Rock Mechanics (IRSRM) as the ISRM National Group of Iran, which had been an important member of our society but had a brief hiatus due to challenging circumstances. The National Group of Iran has a strong history of hosting ISRM events and active participation of its members in the Board and Commissions. We extend our support and look forward to the future activities of these two new National Groups.

The 2024 ISRM International Symposium was held in conjunction with the 13th Asian Rock Mechanics Symposium in New Delhi, India, in September. During the Council Meeting, revisions to By-law No. 4 and By-law No. 7 were approved. The first amendment eliminated the page quota for proceedings at ISRM Congress and allowed non-members to submit papers. The second clarified the nomination period for the Rocha Medal in relation to the timing of degree completion. Additionally, voting took place to decide the venue for the 2026 ISRM International Symposium, with Fukuoka, Japan, being selected. We hope for your interest and participation in the ISRM International Symposium and ARMS14 in November 2026 in Fukuoka. We thank the National Group representatives for their review and approval of the key agenda items during the Council Meeting.

In the New Delhi Symposium, there were six keynote lectures, the Rocha Medal Award Lecture, and the Franklin Lecture. This was followed by a tribute session for Eda Quadros, during which, in accordance with Indian traditions, rose petals were laid before a portrait. Tributes were shared by several individuals, including Dr. Nick Barton. Programs for students and young scholars, such as the Rock Bowl and Early Career Forum, were also held. The Rock Bowl was a great success, thanks to the efforts of Dr. Resmi Sebastian from the Organizing Committee and the National Group of Brazil. Congratulations to Team ADRI for winning the competition. The 9th Early Career Forum featured eight participants from six countries, i.e. Bangladesh, India, Kazakhstan, Malaysia, Mongolia, and Nepal, who presented their research. Senior members Dr. Muriel Gasc-Barbier and Prof. Krishna Panthi kindly shared insightful lectures on career development, focusing on their journeys as a woman and as a professor from a small local area in Asia. Their insights were both valuable and deeply appreciated. We thank all participants and the National Group of China for supporting the Early Career

Forum through the Education Fund. Special thanks to the Indian National Group, Prof. Mahendra Singh, and the organizing committee for their efforts in making all the ARMS13 programs very successful.

Commission activities were vibrant in 2024, with numerous online and in-person meetings, workshops, and conferences. The Commission on Sorptive Rocks hosted its second workshop in Bukowa, Poland, in September, discussing the roles of sorptive rocks in energy transition, carbon capture, and hydrogen storage. Plans for a third workshop in Inner Mongolia, China, in 2025 are underway. The Commission on Coupled THMC Processes in Fractured Rock Mass held the fourth event of the CouFrac series in Kyoto, Japan, in November, featuring six keynote lectures, six Emerging Scientists presentations, a panel discussion on energy storage, and the Chin-Fu Tsang Coupled Processes Award Lecture. The Commission on Radioactive Waste Disposal also held an in-person meeting during this event, discussing plans for a 2025 workshop. The newly launched Commission on Estimation of Rock Mass Strength and Deformability held its inaugural workshop in Lima, Peru, in December, co-hosted by Sri Lanka and Peru National Groups, with 18 presentations sparking in-depth discussions on methodologies. The Commission on Soft Rocks has confirmed plans for a workshop in Porto, Portugal, in May 2025, coorganized by the National Groups of China and Portugal. Meanwhile, the Commission on Testing Methods is developing new Suggested Methods and plans to publish the “Brown Book” with 15–18 Suggested Methods, by 2025 and to hold a workshop in 2026. The dedicated efforts from the Commission Presidents and members are highly appreciated.

In 2024, four ISRM Online Lectures were held, from the 45th to the 48th, featuring outstanding presentations by Dr. Jonny Rutqivist, Prof. Carlos Carranza-Torres, Prof. Ranjith Pathegama Gamage, and Dr. Sylvie Gentier. We deeply appreciate their kind acceptance to prepare and deliver these wonderful lectures.

The FedIGS Board Meeting was held in May 2024 in Toronto, Canada, followed by an online meeting in October. Key discussions since the May meeting focused on the possibility of jointly hosting a conference among sister Societies, similar to the Geoengineering 2000 Conference held in Melbourne, Australia, in 2000. The four participating sister Societies agreed that 2030 would be an appropriate year for such an event. Discussions are ongoing regarding the venue and program to avoid conflicts with each Society’s events. This may necessitate deviations from our By-laws, potentially requiring discussion and approval at the 2025 Council Meeting. We hope this collaborative effort results in a successful event.

Our sister Society, IAEG, celebrated its 60th anniversary in 2024, hosting the EuroEngeo2024 in Dubrovnik, Croatia, in October. At the IAEG Council Meeting, Prof. Resat Ulusay, the immediate Past-President of ISRM, conveyed our society’s congratulations and was honored with the IAEG Honorary Membership Award. Congratulations to Prof. Ulusay on this achievement.

The ISRM Book Series has published eight volumes to date. I thank the editors, Prof. Xia-Ting Feng and Prof. Resat Ulusay, for their efforts. I am pleased to announce that Prof. Ömer Aydan has completed the ninth book, "Geomechanical Aspects of Abandoned Room and Pillar Mines and Remediation Measures", which is set to be published in April 2025. Additionally, three more volumes are in progress. I deeply appreciate the authors’ contributions.

In July 2025, we lost a great scholar, practitioner, and educator in rock mechanics, Dr. Evert Hoek, the first recipient of the ISRM Müller Award. He leaves behind a remarkable legacy of achievements and teachings. His legacy will continue to influence and inspire future generations. Prof. Charles Fairhurst and Prof. Ted Brown, who shared a close relationship with Dr. Hoek, have written an ISRM Tribute to Dr. Evert Hoek, published in the Winter 2024 issue of the ISRM Newsletter. This is a must-read for everyone in the rock mechanics community. Beyond celebrating Dr. Hoek’s contributions and insights, the tribute outlines a vision for the future direction of ISRM. They emphasize the importance of fostering innovative and environmentally sustainable mining technologies, promoting related research at universities, and highlighting the pivotal role of rock mechanics in addressing climate change, utilizing underground spaces, and exploring the “inner space” of our planet. We are deeply grateful to Prof. Fairhurst and Prof. Brown for their exceptional contributions, providing valuable insights and references that will enrich and inspire the entire community.

I wish you a Happy New Year of 2025 with good health, happiness and prosperity. And I hope to meet you in Eurock 2025 this June and other ISRM activities.

Seokwon Jeon

ISRM President 2023-2027

ISRM BOARD ACTIVITIES

ISRM INTERIM BOARD MEETING 2024

San José, Costa Rica

This first meeting of the 2023-2027 ISRM Board took place on 29 February and 2 March, in San José, Costa Rica. The main objective of the meeting was to define and start the implementation of new initiatives for the on-going 4-year term of office. Following presentations by the Board members several decisions were made, namely the preliminarily approval of the list of technical commissions for the term of 2023-2027, and the creation of the Communication Committee with the objectives of promoting communication among ISRM members via diverse platforms and developing contents that can be more engaging, informative, and enjoyable.

In conjunction with the ISRM Board meeting, the Geotechnical Society of Costa Rica hosted the "International Workshop on Recent Advances in Rock Mechanics", on 1 March. This was the first ISRM activity organised in a Central American country. A rich program with presentations by all Board members and several experts from Costa Rica and a fruitful discussion concerning technical issues on topics of interest took place.

ISRM BOARD AND COUNCIL MEETINGS 2024

New Delhi, India

The ISRM held its 2024 Board and Council meetings in New Delhi, India, in conjunction with the 13th Asian Rock Mechanics Symposium - ARMS13, the 2024 ISRM International Symposium.

The ISRM Board held an in-person meeting on September 22. Past activities were reviewed in detail, new initiatives were discussed, and decisions on future actions were made.

The ISRM held its 2024 Council meeting on 23 September in New Delhi, India. 43 National Groups were represented at the Council, which was also attended by the Board members, the Past President Resat Ulusay and observers from the Commissions and the National Groups. Reports of the Board members and Board Committees, as well as the forthcoming conferences were presented. Issues concerning the FedIGS were discussed.

General information regarding the current ISRM statutes and By-laws were presented by the Board. The ISRM has a membership of approximately 9300 individual members and 220 corporate members, belonging to 61 National Groups. After two decades of continuous growth, the number of individual members has stabilized during the last two years. The National Groups of Morocco and Iran joined the Society during 2024.

The National Groups of Macedonia and Japan presented excellent proposals to host the 2026 ISRM International Symposium. The Council, by secret ballot, selected the proposal by Japan, in Fukuoka, from 22 to 26 November, where the 2026 ISRM Board, Council and Commission meetings will take place.

National Groups

The graph below shows the evolution of the number of individual members across the geographic regions since 1996.

The table below shows the change in individual membership of the ISRM and across the geographic regions in the last 1, 5, 10 and 25 years. Individual Members per Region

Out of the total number of 9225 individual members in 2024, 76 are corresponding members and 9149 are registered through their respective National Groups. Compared with the figures reported at the previous Council meeting in October 2023, this represents a decrease of 81 Individual Members. The number of Corporate Members increased by one, and there are two additional National Groups.

The graphs below show the distribution of individual members, corporate members and National Groups across the geographic regions in 2024.

• 1st ISRM Commission Conference on Estimation of Rock Mass Strength and Deformability – an ISRM Specialized Conference, to be held on 6 December 2024, in Lima, Peru.

The following ISRM sponsored conferences are scheduled:

• Eurock 2025 – an ISRM Regional Symposium, to be held on 16-20 June 2025, in Trondheim, Norway.

Individual Members Corporate Members

2. ADDITIONAL ISRM BOARD MEETING

In 2024, a two-day interim Board meeting and a Seminar took place in Costa Rica from 29 February to 2 March. Additionally, the Board convened two three-hour videoconference meetings on 9 July and 4 September. These meetings were held to complement the annual Board meeting and address important matters for the Society.

3. ISRM SPONSORED MEETINGS

Since the last Council meeting on 10 October 2023 in Salzburg, Austria, the following sponsored conferences have taken place:

• 1st Chilean Congress in Rock Mechanics – an ISRM Specialized Conference, held on 22-24 November 2023 in Santiago, Chile.

• 1st SLRMES Conference on Rock Mechanics for Infrastructure and Geo-Resources Development – an ISRM Specialized Conference, held on 2–7 December 2023 in Colombo, Sri Lanka.

• 14th International Symposium on Landsldes (14th ISL) – a FedIGS JTC1 Conference, held on 8-12 July in Chambéry, France.

• Eurock 2024 – an ISRM Regional Symposium, held on 15–19 July 2024 in Alicante, Spain.

• 5th International Conference on Information Technology in Geo-Engineering (ICITG) – a FedIGS JTC2 conference, held on 5-8 August in Golden, Colorado, USA.

• ARMS13 – an ISRM International Symposium, to be held on 22-27 September 2024 in New Delhi, India.

• VietRock2024 – an ISRM Specialized Conference, to be held on 26 October 2024 in Hanoi, Vietnam.

• CouFrac2024 – an ISRM Specialized Conference, to be held on 13-15 November 2024 in Kyoto, Japan

• Landslides 2026, LAGER - co-hosted by the FedIGS JTC1 and JTC3, to be held on 27 April-1 May 2026, in Queenstown, New Zealand.

• LARMS2026 - X Latin American Congress on Rock Mechanics - an ISRM Regional Symposium to be held on 26 - 28 Aug, 2026, in Brasilia, Brazil.

• Eurock 2026 - Risk Management in Rock Engineering - an ISRM Regional Symposium to be hel on 14-19 September 2026, in Skopje, North Macedonia

• JTC2 6th International Conference on Information Technology in Geo-Engineering - an ISRM Specialized Conference to be held on 13-16 October 2026, in Oslo, Norway

• ARMS14 – an ISRM Regional Symposium, to be held on 22-26 November 2026, in Fukuoka, Japan.

• 16th ISRM International Congress on Rock Mechanics, to be held on 17-23 October 2027, in Seoul, Korea.

4. ROCHA MEDAL

For the Rocha Medal Award 2025, 22 applications were received. The Rocha Medal Committee selected the winner and two Proxime Accessit (runner-up) certificate(s).

Rocha Medal 2025: Dr Lucille Carbillet, from France, with the thesis “From grains to rocks: the evolution of hydraulic and mechanical properties during diagenesis”, presented at the Université de Strasbourg

Proxime Accessit (runner-up) 2025 certificate: Dr Georgios Tzortzopoulos, from Greece, with the thesis “Controlling earthQuakes (CoQuake) in the laboratory using pertinent fault stimulating techniques”, presented at the École Centrale de Nantes

Proxime Accessit (runner-up) 2025 certificate: Dr Quan Zhang, from China, with the thesis “Investigation on the principles and applications of directional rock breaking by instantaneous expansion”, presented at the China University of Mining and Technology

5. ISRM AWARDS

In 2024 the following awards were conferred:

• Rocha Medal awarded to Kazuki Sawayama, from Japan

• Rocha Medal runner-up awarded to Kai Liu, from China

• Rocha Medal runner-up awarded to Mingzheng Wang, from China

• Franklin lecture 2024 awarded to Vishal Vikram, from India

• John Hudson Rock Engineering Award 2024, awarded to Yufang Zhang, from China

• Science Achievement Award 2024 awarded to Weiren Lin, from Japan and Pinnaduwa Kulatilake, from Sri Lanka

• Young Rock Engineer Award awarded to Gabriel Walton, from the USA

6. ISRM MULTILINGUAL GLOSSARY ON ROCK MECHANICS

The multilingual glossary of rock mechanics technical terms is available on the ISRM website since March 2015, under the item “Products and Publications. The translation into 19 different languages has been achieved, Mongolian being the most recent language available.

7. ISRM NEWS JOURNAL

The electronic version of the ISRM News Journal, Vol. 26, December 2023, edited by the ISRM President, Prof. Seokwon Jeon and Dr. José Muralha, was uploaded on the ISRM website, where it can be read and downloaded. The Secretariat sent an info-mail to all members, advertising it. 400 hard copies were printed for distribution during the ISRM sponsored conferences. This 84-page issue of the News Journal contains the annual review of the Society’s activity along 2023, and technical articles related to the ISRM awards.

8. ISRM

Since the 2023 Council meeting, five quarterly Newsletters, prepared by the Secretary General, were published: in December 2023, in March, June, September and December 2024. As usual, all ISRM members received them by email. The Newsletters are also available on the website. ISRM National Groups and individual members are welcome to submit to the Secretariat contributions on rock mechanics topics of interest to our technical community.

9. ISRM WEBSITE

The website of the ISRM (http://www.isrm.net), launched on 1 April 2005, is the main means of information of the ISRM and the main channel for communication with the members. Most benefits being offered to the members are available in the password protected members’ area. The information on the website has been continuously updated during the period corresponding to this report.

10.

ISRM YOUTUBE CHANNEL

The ISRM YouTube channel was launched in October 2021. It allows streaming of live events organised by the ISRM

and the storage of videos, such as the European Rock Mechanics Debates. The ISRM Young Members Channel can be reached at https://www.youtube.com/channel/ UCN8FiYOH6LvUMBd9t5uLOyg.

11. DIGITAL LIBRARY

The ISRM Digital Library started in October 2010 and is part of OnePetro.org, a large online library managed by the Society of Petroleum Engineers. ISRM individual members are allowed to download, at no cost, up to 100 papers per year from the ISRM conferences. ISRM corporate members can download 250 papers.

Papers from the ISRM Congresses and sponsored Symposia have been gradually introduced in the library. Currently, the papers from 79 ISRM sponsored events are available, totalling around 13,000 papers and 105,000 pages.

12. ISRM ONLINE LECTURES

The first ISRM Online Lecture was broadcast from the ISRM website in February 2013. From those days to the present days, the ISRM broadcast 47 ISRM Online Lectures given by prominent scholars. All lectures are kept in an appropriate page of the ISRM website. Four ISRM Online Lectures were broadcast during the period corresponding to this report, by Prof. Manchao He, Prof. Jonny Rutqvist, Prof. Carlos CarranzaTorres and Prof. Ranjith Pathegama Gamage.

13. CORRESPONDENCE AND BUSINESS ACTIVITIES OF THE SOCIETY

The Secretary General, assisted by the Secretary and the Webmaster, conducted the correspondence and business activities of the Society, as stipulated in the ISRM Statutes.

The correspondence activity continued to be intense, namely regarding official communications and all sort of demands received by the Secretariat.

The business activities include the daily financial management of the Society and the assistance to the ISRM Board in the preparation of the annual budget and accounts.

14. SUPPORT AFFORDED

As usual, the Secretariat made ample use, at no charge, of several facilities available at the Portuguese National Laboratory for Civil Engineering – LNEC. This included use of office rooms and other facilities offered to the Secretariat, telephone and use of LNEC’s computer network, namely for internet access. This support has long been instrumental to the well-being of the Society and is very much appreciated.

15. FINAL REMARKS

The life of the Society and the activity of the Secretariat during the period corresponding to this report were marked by:

• the stabilization of the number of members of the Society;

• the continuation of an intense activity;

• the maintenance of a sound financial situation.

Luís Lamas ISRM Secretary-General

MEMBERSHIP IN OCTOBER 2024

ROCHA MEDAL 2027

Since 1982 a bronze medal and a cash prize have been awarded annually by the ISRM for an outstanding doctoral thesis in rock mechanics or rock engineering, to honour the memory of Past President Manuel Rocha while stimulating researchers.

In addition to the Rocha Medal award to the winning submission, one or two runner-up certificates may also be awarded.

An invitation is now extended to the rock mechanics community for nominations for the Rocha Medal 2027.

Full details about the Rocha Medal are provided in ISRM By-law No. 7, and all relevant information can be obtained from the ISRM website - isrm.net.

Application

To be considered for the award the candidate must be a member of the ISRM and the official doctorate degree certificate must have been obtained in the two calendar years preceding the year of the selection of the award.

Nominations shall be by the nominee, or by the nominee’s National Group, or by some other person or organization acquainted with the nominee’s work.

Nominations shall be addressed to the Secretary-General and shall contain, in digital format:

• a one page curriculum vitae, including nationality information;

• a written confirmation by the candidate’s National Group that he/she is a member of the ISRM;

Past Recipients

1982 A.P. Cunha PORTUGAL

1983 S. Bandis GREECE

1984 B. Amadei FRANCE

1985 P.M. Dight AUSTRALIA

1986 W. Purrer AUSTRIA

1987 D. Elsworth UK

1988 S. Gentier FRANCE

1989 B. Fröhlich GERMANY

1990 R.K. Brummer SOUTH AFRICA

1991 T.H. Kleine AUSTRALIA

1992 A. Ghosh INDIA

1993 O. Reyes W. PHILIPPINES

1994 S. Akutagawa JAPAN

1995 C. Derek Martin CANADA

1996 M.P. Board USA

1997 M. Brudy GERMANY

1998 F. Mac Gregor AUSTRALIA

1999 A. Daehnke SOUTH AFRICA

2000 P. Cosenza FRANCE

2001 D.F. Malan

SOUTH AFRICA

2002 M.S. Diederichs CANADA

2003 L.M. Andersen SOUTH AFRICA

• a thesis summary, written in English, with between 5,000 and 10,000 words, detailed enough to convey the full impact of the thesis and accompanied by selected tables and figures, and information on word count;

• a copy of the complete thesis and the name of the supervisor(s) if not indicated in the thesis;

• a copy of the doctorate degree certificate;

• a letter of copyright release, allowing the ISRM to copy the thesis for purposes of review and selection only;

• an undertaking by the nominee to submit an article describing the work, for publication in the ISRM News Journal.

Application Deadline

The nomination must reach the ISRM Secretary-General by 31 December 2025.

2004 G. Grasselli ITALY

2005 M. Hildyard UK

2006 D. Ask SWEDEN

2007 H. Yasuhara JAPAN

2008 Z.Z. Liang CHINA

2009 G. Li CHINA

2010 J.C. Andersson SWEDEN

2011 D. Park REP. OF KOREA

2012 M.T. Zandarin ARGENTINA

2013 M. Pierce CANADA

2014 M.S.A. Perera AUSTRALIA

2015 A.L. Bradley ITALY

2016 C.W. Boon MALAYSIA

2017 Bryan Tatone CANADA

2018 M. du Plessis SOUTH AFRICA

2019 Q. Lei CHINA

2020 J. Shang CHINA

2021 Y. Yasuhiro JAPAN

2022 R.S. De Silva SRI LANKA

2023 J. Zhao CHINA

2024 K. Sawayama JAPAN

2025 L. Carbillet FRANCE

2024

THE 2024 ISRM YEAR EVENTS

February - Interim meeting of the ISRM Board, in San José, Costa Rica

- ISRM Board Seminar "International Workshop on Recent Advances in Rock Mechanics", in San José, Costa Rica

- Publication of the 2023 edition of the ISRM News Journal – Volume 26

March

April

- Publication of the e-Newsletter No. 65

- 45th ISRM Online Lecture by Dr. Jonny Rutqvist: “Coupled Processes Modeling in Energy Geosciences”

- 5th European Rock Mechanics Debate: “Rock Bolting: approaches in Mines and in Tunneling” with the speakers Charlie Li from Norway and Robert Galler from Austria.

- Affiliation of the National Group of Morocco, represented by the Moroccan Committee for Soil Mechanics and Geotechnical Engineering

May - 2024 meeting of the FedIGS Board, in Toronto, Canada

June

July

- 14th International Symposium on Landslides – a JTC1 conference in Chambéry, France

- Publication of the e-Newsletter No. 66

- 46th ISRM Online Lecture by Prof. Carlos Carranza-Torres: “Scaled power law failure criterion for rock”

- ISRM Regional Symposium Eurock 2024, in Alicante, Spain

- Interim meeting of the ISRM Board by videoconference

August - 5th International Conference on Information Technology in Geo-Engineering – a JTC2 conference, in Golden, USA

- Reinstatement of the National Group of Iran, represented by the Iranian Society for Rock Mechanics

- ISRM Board meeting in New Delhi

• Dr. Lucille Carbillet, from France was selected as the recipient of the Rocha Medal 2025

• Dr. Yufang Zhang, from China was selected as the recipient of the John Hudson Rock Engineering Award 2024

• Prof. Pinnaduwa Kulatilake, from Sri Lanka and Prof. Weiren Lin, from Japan were selected and the recipients of the Science Achievement Award 2024

• Dr. Gabriel Walton, from the USA was selected as the recipient of the Young Rock Engineer Award 2024

- ISRM Council meeting in New Delhi

• Approval of the audited accounts of 2023 and Budget for 2025

• Revision of By-laws No. 4 and No. 7

• Fukuoka, Japan was selected as the venue of the ISRM International Symposium in 2026

September

- ISRM International Symposium ARMS13, in New Delhi, India

• Dr. Kazuki Sawayama, from Japan presented the Rocha Medal 2024 Lecture

• Dr. Vikram Vishal, from India presented the Franklin Lecture 2024

• The 9th Early Career Forum was held, under the umbrella of the ISRM Education Fund. 8 young members from the Asian region were invited to make presentations.

• Another edition of the ISRM RockBowl competition took place

• Dr. Yufang Zhang, from China was awarded the John Hudson Rock Engineering Award 2024

• Prof. Pinnaduwa Kulatilake, from Sri Lanka and Dr. Weiren Lin, from Japan were awarded the Science Achievement Award 2024

• Dr. Gabriel Walton, from the USA was awarded the Young Rock Engineer Award 2024

- Publication of the e-Newsletter No. 67

- 47th ISRM Online Lecture by Prof. Ranjith Pathegama Gamage: “Deep Geothermal Energy: A Key Player in the Sustainable Energy Mix”

October - ISRM Specialized Conference VietRock2024, in Hanoi, Vietnam

- 15th edition of the Young Members’ Seminar Series

November - ISRM Specialized Conference CouFrac2024, in Kyoto, Japan

- ISRM Specialized Conference 1st ISRM Commission Conference on Estimation of Rock Mass Strength and Deformability, in Lima, Peru

December

- Publication of the e-Newsletter No. 68

- 48th ISRM Online Lecture by Dr. Sylvie Gentier: “New frontiers for deep geothermal energy: some rock mechanics issues...”

ONLINE LECTURE SERIES

Since February 2013 the ISRM Online Lectures Series has been running offering each year four lectures by renowned experts on cutting-edge topics. In 2024 another four high-level lectures were broadcast from the ISRM website at a preannounced date and time. The complete series of online lectures remain available for all interested to watch in the ISRM.

45th ISRM online lecture, March 2024

Dr. Jonny Rutqvist

Coupled Processes Modeling in Energy Geosciences

46th ISRM online lecture, June 2024

Prof. Carlos Carranza-Torres

Scaled power law failure criterion for rock

The lecture first introduces coupled thermal-hydro-mechanical (THM) processes and a modeling tool (TOUGH-FLAC) for analyzing such processes in energy geosciences. Thereafter, three examples of large-scale coupled processes model validations are presented. The first is related to a large underground heating experiment conducted at Yucca Mountain, Nevada, U.S.A. It was an 8-year heating of a 50-m-long tunnel at rock temperatures up to 200˚C, and is the world’s largest underground heating experiment to date. The second example involves an Enhanced Geothermal Systems (EGS) demonstration project, at the Geysers geothermal field, California; the largest geothermal energy producer in the world. The project involved THM modelling of hydraulic simulation of a cubic kilometer sized rock volume during a one-year massive cold-water injection into the very hot >250˚C steam-filled fracture rock. The third and final example involves coupled THM processes modeling at the In Salah CO2 storage project in Algeria. Detailed modeling of observed ground surface uplift revealed the creation of a large-scale fracture zone, about 5 km long, in the lower part of the caprock. These three examples, along with numerous other studies, demonstrate the great value of effective coupled THM modeling for design and performance of subsurface energy resources exploration and storage.

The lecture is based on a keynote paper presented in the first the First Chilean Rock Mechanics Congress in Santiago, Chile in November 2023. The lecture presents the formulation of a general power law failure criterion expressed in terms of principal stresses, and normal and shear stresses on the failure plane. The Mohr-Coulomb and Hoek-Brown failure criteria are shown to be particular cases of the general power law failure criterion. The Griffith failure criterion for intact rock, and the generalization of this criterion proposed by Fairhurst in 1964, are also shown to be particular cases of the general power law failure criterion. A scaling rule for the mathematical expressions conforming the power law failure criterion is presented, and its application in the interpretation of triaxial tests results in samples of intact rock that obey the Hoek-Brown and Fairhurst criteria is discussed. The lecture addresses then the problem of determining damage around boreholes in intact rock by estimation of extent of plastic failure and wall convergence of the borehole. Application of the scaled form of the Hoek-Brown and Fairhurst failure criteria is shown to lead to compact dimensionless representations of the extent of plastic failure and borehole wall convergence. Considering that the Fairhurst failure criterion is associated with the Griffith failure criterion, which in turn is based on the assumption that the combination of principal stresses in the criterion leads to the initiation of crack propagation, a conceptual model is introduced in which the Hoek-Brown failure criterion is applied to quantify the extent of failure around the borehole, while the Fairhurst criterion is applied to quantify the extent of fracturing or cracking beyond the failure zone. Additional developments related to shear strength of rockfill materials, included in the paper on which the lecture is based on, are also discussed.

47th ISRM online lecture, September 2024

Prof. Ranjith Pathegama Gamage

Deep Geothermal Energy: A Key Player in the Sustainable Energy Mix

The lecture discusses recent breakthroughs in geothermal energy, with a focus on innovative extraction techniques aimed at establishing geothermal energy as a sustainable energy cornerstone. This lecture reviewed the global and Australian geothermal landscape, underscoring geothermal's vast potential to meet both energy demands and greenhouse gas reduction targets.

Among the cutting-edge methods highlighted were hydraulic stimulation techniques employing advanced fluids, such as supercritical CO2 (ScCO2) and specialized foams. ScCO2 stimulation was shown to create complex fracture networks that optimize fluid flow and facilitate CO2 sequestration, making it a highly effective and eco-friendly alternative to conventional water-based methods. Foam stimulation further enhances geothermal extraction, requiring minimal water, reducing induced seismicity, and enabling carbon storage when CO2-based. These fluid-based techniques offer scalable solutions that significantly lower environmental impact while maximizing energy recovery.

The lecture also introduced the Slow Releasing Energy Material Agent (SREMA), a novel, sustainable approach to rock fracturing. SREMA’s gradual expansion mechanism permits precise control over rock fracturing, improving permeability with minimal environmental disruption compared to traditional techniques. This eco-friendly innovation represents a breakthrough in geothermal and mineral recovery applications.

Thermal stimulation was another key advancement presented, leveraging temperature-induced fracture networks to improve flow paths within geothermal reservoirs. The integration of thermal, ScCO2, and foam-based methods can substantially boost geothermal output, as evidenced by projects like the Habanero field in Australia’s Cooper Basin, where closed-loop systems sustainably harness geothermal heat with a reduced environmental footprint.

These advancements not only provide a viable pathway to net-zero emissions but also offer a scalable solution to global energy needs. By coupling geothermal energy with green hydrogen production, these technologies support a resilient and sustainable fuel future, emphasizing geothermal's critical role in driving the global energy transition and Australia’s leadership in pioneering these efforts.

48th ISRM online lecture, December 2024

Dr. Sylvie Gentier

New frontiers for deep geothermal energy: some rock mechanics issues

The world of deep geothermal energy, traditionally organized around two clearly individualized poles (geothermal power and heat production), must now consider new perspectives, with a convergence between the contribution of 30 years of development of the EGS (Enhanced Geothermal Systems) concept and the contribution of technologies developed over the last twenty years in the O&G field.

The evolution from HDR (Hot Dry Rock) to EGS is illustrated by the development of the Soultz-sous-Forêts site (Alsace, France). This evolution is reviewed in general terms and through rock mechanics issues addressed by the scientific community and more specifically by BRGM (French Geological Survey) and its collaborators over the last 30 years. The first industrial pilot plant connected to the electricity grid was completed in 2008, opening the door to the development of power-generating or cogenerating (electricity/heat) geothermal energy, to be deployed with a more widespread exploitation of deep heat.

The deployment expected and foreseen in the years 2015-2020 has faced difficulties of various kinds: drilling technology and cost, induced seismicity. New fundamental questions about the knowledge of faulted and/or fractured media and their thermo-hydro-mechanical behavior in response to the construction of underground heat exchangers and their operation are discussed.

At the same time, the last twenty years have seen the widespread deployment of shale gas exploitation in the USA, leading to increased technological expertise in drilling (horizontal drilling) and hydraulic fracturing. How the transfer of these technologies to the development of EGS which is likely to give new dynamism to these technologies, with the hope of removing some barriers and minimizing certain risks, is presented.

Finally, this EGS perspective is compared with what we now call AGS (Advanced Geothermal Systems) and the associated research questions.

ISRM COMMISSIONS

The objective of ISRM Commissions is to study scientific and technical matters of interest to the Society. In recognition of the critical role of the ISRM Commissions, the ISRM Board created a committee – the Technical Oversight Committee (TOC) to coordinate the commission’s work, report on their performance and to act as oversight for the Commissions. Since ISRM Commissions are appointed by the Board for each 4-year period between ISRM Congresses, establishment of new Commissions or the continuation of pre-existent ones is decided by the new Board following proposal by the TOC.

In the Interim ISRM Board meeting held in San José, Costa Rica, 21 commissions were preliminarily approved for the term 2023-27.

Later in the year, the Board approved the establishment of one additional commissions, bringing the total number of active commissions to 22, as listed below along with the respective chairs and contacts followed by the topics and objectives of the nine new ones.

There are four Joint Technical Committees operating under the umbrella of the Federation of International Geo-Engineering Societies - FedIGS. The current list of JTCs is the following:

JTC 1 - Natural Slopes and Landslides

JTC 2 - Representation of Geo-engineering Data in Electronic Form

JTC 3 - Education and Training

JTC 4 - Environment and Geo-Engineering Sustainability

Artificial Intelligence in Rock Mechanics and Rock Engineering

Beyond Limits: Rocks in the Face of Extreme Conditions

Bio-Rock Mechanics

Coupled Thermal-Hydro-Mechanical-Chemical Processes in Fractured Rock

Crustal Stress and Earthquakes

Deep Mining

Design Methodology

Discontinuous Deformation Analysis - DDA

Earthquake Motions in Rock Engineering

Estimation of Rock Mass Strength and Deformability

Mechanics of Ancient Rock Structures

Planetary Rock Mechanics

Radioactive Waste Disposal

Risks and Reliability in Rock Slope Engineering

Rock Dynamic

Rock Grouting

Rock Weathering and Erosion

Rockburst

Soft Rocks

Sorptive Rocks and Engineering

Testing Methods

Ultradeep Rock Mass Mechanics and Engineering

Dr. Hongkyu Yoon, USA (hyoon@sandia.gov)

Dr. Wasantha Liyanage, Australia (wasantha.pallewelaliyanage@ vu.edu.au)

Prof. Hitoshi Matsubara, Japan (matsbara@tec.uryukyu.ac.jp)

Dr. Jonny Rutqvist, USA (jrutqvist@lbl.gov)

Prof. Furen Xie, China (xxiefr@263.net) and Dr. Jiayong Tian, China (chenlitedtian@263.net)

Dr. Abbas Taheri, Canada (abbas.taheri@queensu.ca)

Prof. Xia-Ting Feng, China (fengxiating@mail.neu.edu.cn)

Prof. Yu-Yong Jiao, China (yyjiao@cug.edu.cn) and Prof. GaoFeng Zhao, China (gaofeng.zhao@tju.edu.cn)

Dr. Naoki Iwata, Japan (n.iwata@cecnet.co.jp)

Prof. Pinnaduwa Kulatilake, Sri Lanka (kulatila@arizona.edu)

Dr. Takafumi Seiki, Japan (tseiki@cc.utsunomiya-u.ac.jp)

Prof. Serkan Saydam, Australia (s.saydam@unsw.edu.au)

Dr. Ju Wang, China (wangju9818v163.com)

Dr. Neil Bar, Hungary (neil@geckogeotech.com)

Prof. Jianchun Li, China (jcli@seu.edu.cn)

Mohamed El Tani, Switzerland (md.eltani@rockgro.com)

Yanli Huang, China (huangyanli@cumt.edu.cn) and Zhongwei Chen, Australia (zhongwei.chen@uq.edu.au)

Prof. Manchao He, China (hemanchao@263.net)

Prof. Xiaoming Sun, China (sxmcumtb@163.com)

Dr. Shimin Liu, USA (szl3@psu.edu) and Dr. Yixin Zhao, China (zhaoyx@cumtb.edu.cn)

Prof. Rešat Ulusay, Turkey (resat@hacettepe.edu.tr)

Prof. Yangsheng Zhao, China (y-s-zhao@263.net) and Prof. Derek Elsworth, USA (elsworth@psu.edu)

ARTIFICIAL INTELLIGENCE IN ROCK MECHANICS AND ROCK ENGINEERING

The ISRM Commission on Artificial Intelligence in Rock Mechanics and Rock Engineering (CAIRM) focuses on the applications of artificial intelligence (AI) and big data in rock mechanics, geomechanics, and engineering works in rock masses in support of civil, geo-, petroleum, and mining engineering. The main objectives of CAIRM include promoting the development and applications of AI and machine learning for the field of rock mechanics and rock engineering, sharing AI tools and big data among researchers, professionals, and rock mechanics and engineering practitioners, and encouraging international collaboration and exchange of ideas through the commission and ISRM activities.

BEYOND LIMITS: ROCKS IN THE FACE OF EXTREME CONDITIONS

Rocks exposed to extreme conditions, e.g., extremely high and extremely low temperatures, extremely high pressures, dynamic loading, and creep, are increasingly encountered in rock mechanics and rock engineering applications around the world. This trend is largely attributed to factors like climate change, fire (wildfire, tunnel fire, mine fire, etc.), deep mining, underground storage initiatives, and geothermal energy exploitation. Consequently, there is a growing need to reassess and adapt relevant theories and practices in rock mechanics to tackle these encounters effectively. The primary aim of this Commission is to materialise necessary advancements in understanding rock behaviour under such extreme conditions, pushing beyond conventional boundaries.

BIO-ROCK MECHANICS

Microorganisms have been essential to the weathering and mineralization of the Earth’s crust since their emergence. However, our understanding of how the physicochemical and geochemical properties of rocks, alongside biogeochemical parameters, influence and control the mechanical behavior of rocks remains limited. To clarify the relationship between microbial activity in rocks, the mechanical/material properties of rocks, and geo-hazards, the establishment of a novel field called “bio-rock mechanics” is essential. This commission aims to promote comprehensive research on microbial weathering and mineralization phenomena, while encouraging collaboration and fostering scholarly exchange among scientists in this field.

EARTHQUAKE MOTIONS IN ROCK ENGINEERING

Earthquakes are known to be one of the natural disasters resulting in the huge losses of human lives as well as of properties as experienced in the recent great earthquakes. It is well known that ground motion characteristics, deformation and surface breaks of earthquakes depend upon the causative faults. Every earthquake causes vibrations and temporary and/ or permanent movement of ground. As it is difficult to measure ground motions at every location, empirical, semi-analytical or numerical procedures are utilized to estimate ground motions.

ESTIMATION OF ROCK MASS STRENGTH AND DEFORMABILITY

The main goals of this commission are to provide a review of the available methods (empirical, numerical modelling, back calculation based on field monitored data), to provide guidelines for rock mechanics teaching and practice, and to suggest future research to improve the available techniques in predicting rock mass strength and deformability properties.

MECHANICS OF ANCIENT ROCK STRUCTURES

Mankind has built rock engineering structures going back to 5000 years at least. Research on learning from ancient rock engineering structures definitely provides essential information and data for assessing the long-term behaviour and performance of some modern rock engineering structures. Therefore, a commission with the goal of learning and obtaining data and information from Ancient Rock Engineering Structures is doubtlessly necessary within the activities of ISRM Commissions. In the pathway of the commission led by Emeritus Prof. Chikasa Tanimoto on “Preservation of Natural Stone Monuments Commission” activities in 1996 and lasted till 2007, the proposed commission intends to further advance research goals on the rock mechanics and rock engineering aspects of Ancient Rock Engineering Structures.

RISKS AND RELIABILITY IN ROCK SLOPE ENGINEERING

The ISRM Commission for Risks and Reliability in Rock Slope Engineering provides a forum for sharing ideas and challenges relating rock engineering design related to surface excavations in mining and civil engineering. The commission is focusing on addressing uncertainty in ground characterization to produce guidelines for reliability analyses and risk management in rock slope engineering for surface excavations. This will also include guidance on the application of reliability-based analyses for different rock engineering problems, such as rockfalls, stability problems during excavation, as well as for the selection of parameters and design cases from Eurocode 7 related to rock mechanics and rock engineering.

ROCK WEATHERING AND EROSION

The importance of studying rock weathering and erosion is increasingly evident across various aspects, including rock lithological alteration and deterioration and their engineering implications on mine rehabilitation, the preservation of open pit mines, stability assessments in underground excavations, carbon sequestration through enhanced weathering, and safeguarding heritage sites.

The proposed Commission seeks to reveal the underlying mechanisms of rock weathering and erosion across diverse rock types, establish robust quantitative methods for tracking their time-spatial evolutions, and develop innovative solutions to mitigate weathering and erosion effects in specific applications.

ULTRADEEP ROCK MASS MECHANICS AND ENGINEERING

The commission covers the field of ultradeep resource development such as hot dry rock geothermal resources (depth>5000 m and temperature>300°) and coal mining (depth>1500 m), ultradeep geological energy storage such as oil & gas and hydrogen geological storage (depth>3000 m), CO2 ultradeep geological storage (depth>4000 m), ultradeep drilling (depth>8000 m), and earthquake prediction (depth>10000~15000 m) in ultradeep geological mass to address rock mass mechanics and engineering problems and challenges under ultradeep in-situ geological buried conditions. To determine the occurrence, geological and structural characteristics of ultradeep rock mass as well as the rock mass behavior during the long-term migration and storage of the working medium are very important for the engineering design of resource exploitation and geo-hazards prediction in the related fields.

AWARDS

ROCHA MEDAL

At its Tokyo meeting in September 1981, the ISRM Board decided to institute an annual prize to honour the memory of Prof. Manuel Rocha, ISRM President from 1966-1970. The Rocha Medal is intended to stimulate young researchers in the field of rock mechanics. The prize, a bronze medal and a cash prize, have been annually awarded since 1982 for an outstanding doctoral thesis selected by a committee appointed for the purpose.

The 2024 Rocha Medal was conferred to Dr. Kazuki Sawayama, from Kyushu University, Japan, with a thesis entitled “Study on the relationships between fracture flow behaviours and geophysical properties for the quantitative monitoring of fractured reservoirs”, and supervised by Prof. Jun Nishijima.

In 2024, two runner up certificates were given to Dr. K. Liu, from Monash University, for the thesis entitled “Dynamic behaviours of rock materials under coupled multiaxial confinement and dynamic loading”, supervised by Prof. Jian Zhao, and to Dr. M. Wang, from Laurentian University, for the thesis entitled “Modeling time-dependent deformation behavior of jointed rock mass”, supervised by Prof. Ming Cai.

FRANKLIN LECTURE

The Franklin Lecture was institute in 2011 in order to honour the memory of Prof. John Franklin, ISRM President from 1987 to 1991. The purpose of the ISRM Franklin Lecture is to recognise a mid-career ISRM member who has made a significant contribution to a specific area of rock mechanics and/ or rock engineering. The ISRM Franklin Lecture is given in every year, at the respective ISRM International Symposium, except for those years when the 4-yearly ISRM Congress is held.

The 2024 Franklin Lecture “Geomechanical constraints in geological carbon dioxide sequestration” was delivered by Dr. Vikram Vishal from India during the ARMS13 Conference held in New Delhi.

JOHN HUDSON ROCK ENGINEERING AWARD

The John Hudson Rock Engineering Award honours the memory of Prof. John Hudson, ISRM President from 2007 to 2011, It can be awarded to ISRM individual or corporate members in recognition of their achievements in engineering practice.

In 2024, this award was attributed to Yufang Zhang, researcher at the China Railway Scientific Research Institute from China, for his research and application of ultra-high and large energygrade flexible protective structure for high position rockfalls on the Chengdu-Kunming Railway, which was recognized as a relevant realization the effectively introduced new and important technologies to current rock engineering practice. This recognition marks Zhang as the first Asian scholar to receive this prestigious award, underscoring his remarkable achievements in rock engineering.

YOUNG ROCK ENGINEER AWARD

The Young Rock Engineer Award was instituted to acknowledge excellence in the field of rock engineering by ISRM members who are in early stages of their career: under the age of 40 and having worked in rock engineering for a period of about five to ten years.

The Young Rock Engineer Award 2024 was conferred to Dr. Gabriel Walton, from Canada and based in the United States.

Dr. Walton received his B.A.Sc. and Ph.D. in Geological Engineering from Queen’s University (Kingston, Canada) in 2011 and 2014, respectively.

After a brief stint in consulting, he joined the faculty of the Colorado School of Mines in 2015. He has published over 100 peer-reviewed papers, and is an active member of the Rock Engineering community, serving on the Board of Directors of the American Rock Mechanics Association (ARMA) since 2021, as Vice President of ARMA since 2023, and as the Chair of the 2024 ARMA symposium in Golden, Colorado. He was runner-up for the ISRM Rocha Medal in 2017 and received the Faculty Excellence in Research Award from the Colorado School of Mines in 2024.

Dr. Walton’s research group has contributed to the solution of practical engineering problems through collaborations with a variety of industry partners, including addressing deep shaft stability in highly anisotropic ground, application of look-ahead geophysics in tunneling, and application of drone-based monitoring to evaluated potential trends in underground mine convergence. His group has also advanced broadly applicable tools and approaches, including developing modifications to the Voussoir Beam model for flatroofed excavation stability to consider the influence of rock reinforcement, proposing improvements to existing pillar strength estimation methods, and developing best practices for numerical modeling of brittle rock damage and excavation stability. Most recently, Dr. Walton group has focused on the use of point clouds (lidar and photogrammetry) for rock slope monitoring and the application of monitoring results to improve rock slope asset management.

SCIENCE ACHIEVEMENT AWARD

The Science Achievement Award is conferred by the ISRM President, on a bi-annual basis, in the 1st and the 3rd year of each ISRM Presidential tenure period, on up to two ISRM individual members in recognition of one or more of the following contributions to the progress of the science of rock mechanics: making an important advancement of knowledge, or proposing and confirming a new theory to explain certain phenomena.

This year the recipients of this award were Prof. Pinnaduwa Kulatilake, from Sri Lanka, and Prof. Weiren Lin, from Japan.

Prof. Pinnaduwa H.S.W. Kulatilake is a Professor Emeritus at the University of Arizona, USA, and the President of the Sri Lankan Rock Mechanics and Engineering Society. His Ph.D. degree is in Civil Engineering with a Geotechnical Engineering specialty from the Ohio State University, USA. Prof. Kulatilake has over 40 years of experience in rock mechanics and rock engineering and applications of probabilistic, statistical, and numerical methods to civil, mining, and geoengineering.

His teaching has gone beyond the universities he has worked at. He has taught 56 short courses to both practitioners and academicians in 17 countries covering all 6 continents. He has performed research with 95 graduate students, and visiting scholars to earn worldwide recognition for his research. His visiting scholars were supported by various agencies in China, Japan, Turkey, Europe, and India. He has collaborated with industry, research institutes, and universities in many parts of the world for his research, teaching, and service activities. He has published more than 280 papers, which resulted in more than 7850 citations. He has co-authored a book on “Rock mass stability around underground excavations in a mine”, he has edited four conference proceedings and served as the Guest Editor for two special issues in an international journal. All those activities led him to deliver more than 40 invited keynote lectures and 50 other invited lectures throughout the world.

Recently, he formed the Sri Lankan Rock Mechanics and Engineering Society (SLRMES) as a member country under the International Society of Rock Mechanics and has been serving as the President of the SLRMES since October 2022. He has organized and chaired three successful international conferences, the most recent one, which was an ISRM Specialized Conference, was held in Sri Lanka in December 2023.

Prof. Kulatilake has performed research in two specific fields. In the rock mechanics area, his research has been on the topics of discontinuity geometry, roughness, and aperture; discontinuity strength, deformability, and fluid flow modeling; rock mass deformability; rock mass strength; rock mass hydraulic behavior; civil-geotechnical rock slope stability; open pit and underground mine stability; geohazards; and rock blasting. In his second area of research, he developed and/ or applied probabilistic, statistical, and numerical methods to solve geo-engineering problems.

Based on more than 15 highly innovative journal papers his research group published on rock joint geometry parameters, his group developed a highly sophisticated computer package incorporating 26 calculation programs and 24 graphical programs to perform discontinuity network modeling including validations in rock masses in 3D.

Prof. Weiren Lin has dedicated approximately 30 years to the study of rock mechanics in the fields of geoengineering and geoscience. His primary research interest lies in the in-situ stress state of rock mass in deep subsurface rock formations. This includes stress measurement techniques, interpreting the geomechanical and scientific implications of stress states, and developing stress measurement methodologies. His secondary research interest lies in the evaluation of the physical properties of rock, such as thermal conductivity, compressive/tensile strength, elastic wave velocity, resistivity, and permeability under high-pressure and high-temperature conditions. Prof. Lin has published 110 peer-reviewed papers in international journals, including three papers published in top journals (Nature or Science), 52 papers published in peerreviewed domestic (Japanese) journals, 51 papers published in international conference proceedings (for example, ISRM Congress), six invention patents, and six book chapters.

Notably, Weiren Lin has successfully measured the postearthquake stress state around the Pacific and North American plate boundary fault, which caused the 2011 Mw 9.0 Tohoku earthquake. With his colleagues, he concluded that a complete stress drop occurred, which increased the faultslip displacement and eventually resulted in a devastating tsunami. This research, which was based on rock mechanics measurements, was published in ‘Science’ with Weiren Lin as the first author, and made an important advancement of knowledge to the fields of geoscience and geoengineering.

Weiren Lin’s major scientific achievements are:

• determining stress state in vicinity of earthquake-source faults and stress drop accompanied by the 2011 Mw 9.0 Tohoku earthquake;

• development of stress measurement methods and their application

• measurement of physical properties under high-pressure and high-temperature conditions.

The Mw 9.0 earthquake produced a maximum coseismic slip of >50 m on the plate boundary fault close to the Japan trench, triggering a devastating tsunami. Before the earthquake, it was widely accepted that an earthquake releases only part of the stress driving the earthquake fault. To elucidate the recordbreaking displacement of the coseismic fault-slip, Prof. Lin and colleagues conducted stress measurements using conventional rock mechanics methods in deep ocean drilling that penetrated the earthquake-source fault at a depth of approximately 820 m below the seafloor, at a water depth of approximately 7000 m. The stress measurement results based on borehole breakout

analyses and the anelastic strain recovery (ASR) method indicated a complete stress drop and large energy release during the earthquake. This complete stress drop increased the coseismic fault slip and resulted in a devastating tsunami. By using actual stress measurement data obtained by rock mechanics approaches, this research led to the discovery of unexpected stress drop during the enormous earthquake. This initial discovery marked a significant leap forward in understanding the correlation between earthquake occurrence and stress changes, highlighting the pivotal role of stress measurements in seismic research.

The determination of in-situ stress states is one of the most important issues in rock mechanics and rock engineering. However, significant challenges persist in refining measurement techniques for this purpose. In the past two decades, Prof. Lin and colleagues have established a practical test protocol and data processing procedure for determining three-dimensional in-situ stresses from anelastic strain recovery (ASR) measurements. They have conducted over ten case studies with in-situ stress measurements using the core-based ASR technique, including deep drilling projects both on land and in marine environments, spanning diverse geoengineering and geoscience applications). These case studies covered a wide range of rock types, core sample retrieval depths, and research backgrounds. The success of these applications confirmed that the ASR technique is useful and applicable to most deep-drilling, particularly to deepdrilling that penetrates sedimentary rocks. Additionally, Prof. Lin has used borehole breakouts analysis to determine the insitu stress in various drilling projects. The stress measurement methods developed by Prof. Lin have provided the rock mechanics community with valuable resources for planning, conducting, and evaluating stress measurements.

The physical properties of rocks depend on pressure and temperature, which increase with depth in the deep subsurface, particularly in large depths of several kilometers. For the correct evaluation of the physical properties of rock, such as the thermal conductivity, Prof. Lin and colleagues have carried out physical property measurements under high-pressure and high-temperature conditions to simulate the actual in-situ conditions. To elucidate the mechanisms behind the impact of high temperature on the physical properties of rock, Weiren Lin investigated the thermal microcracking of granitic rocks subjected to high-temperature. His experimental studies on the physical properties of rock have contributed a wealth of valuable data to the field of experimental rock mechanics.

European Rock Mechanics Debates started in 2021 and aim at stimulating communication among academics and practitioners of rock mechanics and rock engineering in Europe, organized initially by the Vice-President for Europe Leandro Alejano supported by Charlie Li and Philippe Vaskou. The debates are held virtually and each one will have two speakers, with different perspectives on a hot rock engineering topic or on a specific technical aspect of rock mechanics. 2024 saw two more editions of these events again moderated by Philippe Vaskou, from France.

5TH ISRM EUROPEAN ROCK MECHANICS DEBATE

Rock bolting: approaches in mines and tunneling

safety, reduces ground movement, and increases the bearing capacity of the ground, making it a valuable solution in construction and mining projects. The process requires careful site analysis, accurate design, and precise execution to be effective.

Why Rock Bolting is Done in Soft Ground Conditions:

: Soft ground, such as clay, silt, or loose sand, often lacks the strength to support excavations or structures without additional reinforcement. Rock bolting helps stabilize the ground, providing support to prevent collapses or failures.

load reaches the ultimate load of the bolt stem. The distribution of the axial load in a frictional bolt is similar as in a fully grouted bolt before slip occurs. The distribution of the axial load in a dynamic energy-absorbing frictional bolt is similar as in an end-anchored conventional static bolt, but its ultimate load and displacement capacity are significantly higher than the latter. Some issues related to rockbolting design are also outlined in the end of the presentation.

Preventing Ground Deformation: In soft ground, soil and rock layers can deform or shift when loads are applied, particularly during construction or excavation activities. Rock bolts help prevent unwanted movements, reducing the risk of subsidence, landslides, or cracking in structures.

• Cost-Effective Reinforcement: In some cases, rock bolting can be a more economical solution than complex mechanical stabilizing techniques, especially in projects requiring only moderate reinforcement.

• Increase Bearing Capacity: By anchoring the soil and weak rock layers to stable strata deeper underground, rock bolts improve the bearing capacity of the ground, allowing for the safe construction of buildings, roads, or tunnels.

Types of Rock Bolts Used in Soft Ground Conditions:

• Solid Rock Bolts: Steel bars with end plates or resin anchors, useful in semi-consolidated soft rock or fractured ground.

• Resin-anchored Bolts: Used in more fractured soft rock or when the ground conditions are not stable enough to anchor directly into the rock.

• Cable Bolts: Steel cables that provide greater flexibility and can be tensioned more easily, often used for larger-scale stabilization of soft ground or tunnel linings.

• Fiberglass or Composite Bolts: These are lighter and resistant to corrosion, used where durability and performance are key in wet or acidic ground conditions.

6TH ISRM EUROPEAN ROCK MECHANICS DEBATE

Failure criteria: Mohr-Coulomb vs Hoek&Brown

MOHR-COULOMB FAILURE/ YIELD CRITERION AND REMARKS ON A GENERALIZED LINEAR THEORY

Joseph F. Labuz | University of Minnesota, USA

The popular Mohr-Coulomb (MC) failure criterion is a reasonable approximation to strength data for isotropic rock, featuring a linear relation between major σI and minor σIII principal stresses with fitting parameters on a Mohr diagram known as friction angle and cohesion (σs intercept). Criticisms of MC are the absence of the intermediate principal stress and the inability to represent a curved failure surface. A general linear theory called Paul-Mohr-Coulomb (PMC) removes these limitations by (a) including all three principal stresses and (b) approximating a nonlinear failure surface with piecewise linear segments. The fitting parameters for PMC are the friction angle for axisymmetric compression φc, friction angle for axisymmetric extension φe, and isotropic tensile strength Vo (σn intercept). Note that PMC reduces to MC if φc = φe. Further, the nonlinear shape of the MC failure surface can be approximated in a piecewise linear manner with planes P1 and P2, each with friction angle φ (i) and strength Vo(i)

MC planes P1 and P2 fitted to approximate the nonlinear failure surface in the Mohr diagram; tension cutoff criterion −σIII = T = uniaxial tensile strength is included.

HOEK-BROWN FAILURE CRITERION

Ming Cai | Laurentian University, Canada

Rock and rock mass strengths are required in rock engineering design. The Hoek–Brown failure criterion, now integrated into most geotechnical modeling tools, is one of the most widely used criteria in rock mechanics and rock engineering. This presentation traces the development of the Hoek–Brown failure criterion from its initial formulation for intact rock to its later generalization for jointed rock masses. The criterion for intact rock is an empirical failure criterion based on data fitting of laboratory test data, and it describes rock strength better than the Mohr–Coulomb failure criteria over a wide range of confinement, including in the tension zone. The generalized Hoek–Brown criterion provides a practical tool for engineers to estimate rock mass strengths in engineering designs. The creation of the Geological Strength Index (GSI) addressed the challenge of linking geological conditions to rock mass strength. GSI is determined by rock mass structure and joint surface conditions, which can be assessed using field mapping data. A method for quantifying the GSI is presented, along with examples demonstrating the application of the Hoek–Brown failure criterion in rock engineering design analyses. The importance of implementing a field monitoring program to verify design analysis employing the Hoek–Brown failure criterion is emphasized. Finally, the assumptions and limitations of the Hoek–Brown failure criterion are discussed in comparison to the Mohr–Coulomb failure criterion.

ISRM YOUNG MEMBERS’ SEMINAR

The ISRM Young Members’ Seminar (YMS) Series consists of virtual events aimed at providing a global platform for ISRM young members to share knowledge, experiences, and ideas. The events foster knowledge and friendship among young professionals and students of rock mechanics and rock engineering on an international scale. The ISRM Young Members Committee and the YMS organising committee invite young members with careers in research or industry, working in the public or private sectors, to participate and share their work with the broader rock mechanics and rock engineering community.

Since its establishment in November 2021, the ISRM Young Members’ Seminar Series provided a platform for young members to collaborate and showcase their achievements to their peers. In 2024, the organizing committee delivered three live seminars with 11 speakers from all over the world. The recordings of these presentations are available on ISRM Young Members YouTube channel https://bit.ly/ youtubeisrmymchannel.

13th seminar - 21st February 2024

Numerical modeling of rock fracture processes: Investigating mechanisms of rock fracture under dynamic loading in laboratory and small-scale tests. Gyeongjo Min, Jeonbuk National Univ., South Korea

Forecasting potential rock slope failure in open pit mines using the state of the art of technology. Rachmat Musa, Ground Probe, Indonesia

Numerical simulations of hydraulic fracturing using water or CO2 for volcanic rock under geothermal conditions. Yutaro Maeda, Osaka University, Japan

Laboratory earthquakes decipher control and stability of rupture speeds. Peng Dong, China University of Geoscience, China

14th seminar - 17th June 2024

Partially depleted oil and gas reservoir rock as a possible CO2 storage: experimental study. Cecília Belén Laskowski. Universidad Nacional de la Patagonia San Juan Bosco, Argentina, and Universidad Politécnica de Madrid, Spain

Characterization of the variability and uncertainty in in situ stress using Bayesian statistics. M. Amir Javaid, University of Toronto, Canada

Geomechanics of injection-induced seismicity in Illinois Basin. Nikita Bondarenko, University of Illinois, Urbana-Champaign, USA

15th seminar - 23rd October 2024

Probabilistic Analysis of a Rock Salt Cavern with Application to Energy Storage Systems. Elham Mahmoudi, Deltares, The Netherlands

Size effects on strength and deformability of intact and artificially-jointed hard rock samples. Manuel A. González Fernández, University of Vigo, Spain

Using Synthetic Rock Mass and Discrete Fracture Network approaches to study rock mass strength properties. Étienne Lavoine, Itasca Consultants S.A.S., France

A hybrid approach for adequate rock support design in hard rock tunnelling. Jorge Terron Almenara, Norwegian University of Science and Technology, NTNU, Norway

NEW NATIONAL GROUPS

In March 2024, the Moroccan Committee for Soil Mechanics and Geotechnical Engineering (MCSMGE) was approved by the Board as the ISRM NG of Morocco.

MCSMGE is a non-profit professional society, whose members work in the construction sector for various organizations, as project owners, design offices engineers, university professors and researchers. The goal of the society is to promote studies directly or indirectly linked to soil and rock mechanics, for foundation and excavation practice, special construction techniques related to soils and rocks with the purpose of sharing up to date results and lessons learned from special projects with the scientific community.

President: Mustapha Fares

NEW VIDEOS OF ISRM

SUGGESTED METHODS

Based on the cooperation between several universities, rock mechanics laboratories and the ISRM Commissions on Testing Methods, video films depicting the execution of several ISRM Suggested Methods prepared mainly for educational purposes are embedded on the webpage of the Commission on Testing Methods.

This initiative is an attempt to provide detailed explanations on the ISRM Suggested Methods. Twelve videos have been recorded from experiments conducted in the Rock Mechanics and Rock Engineering Laboratory of the Seoul National University, South Korea, the Laboratorio de Mecanica de Suelos e Rocas of the Alicante University, and the Laboratorio de Geotecnia (Geotechnical Laboratory) of the CEDEX (Madrid, Spain).

In September 2024, the Iranian Society of Rock Mechanics (IRSRM) was reinstated as the new National Group of Iran.

IRSRM is a dynamic organization that has been dedicated to advance the field of rock mechanics in Iran. The board of directors holds meetings every two weeks to ensure effective governance and strategic planning. It organizes monthly scientific seminars on topics related to rock mechanics, featuring both domestic and international speakers. Furthermore, IRSRM regularly conducts educational workshops and technical field trips for our members. Every two years, IRSRM hosts the national rock mechanics conference in which the latest – the 9th National Rock Mechanics Conference – was held in May 2024 at the Amir Kabir University of Technology (Teheran Polytechnic).

President: Hamid Reza Nejati

Two new videos were added to the list in 2024.

• Mode I Static Fracture Toughness using Semi-Circular Bend Specimens (2024)

• Schmidt Hammer Rebound Hardness (2024)

• Needle Penetration Test (2021)

• Direct Tensile Strength of Rock Materials (Part 1: Suggested Method for Determining Tensile Strength) (2021)

• Strength of Rock Materials in Triaxial Compression (2020)

• Basic Friction Angle of Planar Rock Surfaces by Means of Tilt Tests (2019)

• Shear Strength of Rock Joints (2018)

• Water Content, Porosity, Density, and Wave Velocity (2018)

• Brazilian Tension Test (2018)

• Uniaxial Compressive Strength and Deformability of Rock Material (2018 revised version)

• Point Load Strength (2016)

• Basic Rock Sample Preparation (2016)

IN MEMORY OF

Evert Hoek was born in Zimbabwe in southern Africa in 1933 and graduated in mechanical engineering with a B.Sc and an M.Sc from the University of Cape Town in 1957. He became involved in rock mechanics in 1958 when he started working in research on problems of brittle fracture in rock associated with very deep mines in South Africa. His degrees include a Ph.D. from the University of Cape Town, a D.Sc (Engineering) from the University of London, and honorary doctorates from the Universities of Waterloo and Toronto in Canada and the Polytechnic University of Catalonia in Spain. He is a Fellow of the Royal Academy of Engineering (UK), an International Member of the US National Academy of Engineering, and a Fellow of the Canadian Academy of Engineering.

He spent 8 years as a research engineer in the South African Council for Scientific and Industrial Research, 9 years as a Reader and then Professor in the Imperial College of Science and Technology in London, 12 years as a consultant with Golder Associates in Vancouver, Canada, and 6 years as an Industrial Research Professor in the University of Toronto. For the 25 years prior to his retirement in 2018, he worked as an independent consultant on review and consulting boards on civil and mining engineering projects around the world.

ISRM TRIBUTE TO DR. EVERT HOEK

Dr. Evert Hoek, a long-time international leader in rock engineering, passed away peacefully July 6, 2024, after a brief illness, at home in Vancouver, Canada. In their own words, his family “adored” him.

The international rock mechanics community grieves with you. We have lost a world leader in our field, but we are all the better for his major contributions and for having known him.

Evert was born on August 23, 1933, in what was then Rhodesia (now Zimbabwe) in Southern Africa. His parents were farmers. He studied Mechanical Engineering at Cape Town University and met his wife Theo there. They have two children, son Peter and daughter Dorothy (Fairholm). Theo passed away in 2013. Evert married Bonnie in 2014. He retired in 2018. Throughout his remarkable and busy career Evert was a devoted husband and father. A private celebration of Evert’s life has been arranged by Bonnie and the family.

EVERT HOEK 1933 - 2024

THE ROCK MECHANICS COMMUNITY GRIEVES THE LOSS OF A TRUE GIANT IN ROCK MECHANICS, ROCK ENGINEERING AND IN LIFE.

After receiving his M.Sc. degree in Mechanical Engineering from Cape Town University in 1957, Evert joined the Council for Scientific and Industrial Research (CSIR) laboratory in Pretoria, to conduct research on mechanics and stress analysis. He inherited “a large photo-elastic stress analysis unit”. This had been assembled by a staff member, who had decided to retire soon after it was completed.

In 1960, a major collapse at the Clydesdale underground coal mine, Coalbrook, killed 435 miners, the worst accident in South African history. At the same time, rockbursts in the deep gold mines of the Witwatersrand were killing many miners annually (for details, see the report by the Leon Commission of Inquiry (2005) [1]. Dr. Francis G. (“Pinky”) Hill, a visionary mining leader in South Africa, was urging research on this issue. In 1963, Dr. M.D.G. Salamon was appointed Director of Research for the South African Coal Mining Research Controlling Council. In 1964, the government Chamber of Mines established the Mining Research Laboratory (MRL) with Dr. N.G.W. Cook as Director. In 1966, Dr. Salamon was made Director of Research into the Stability of South African coal mines, and then appointed Director of the Collieries Research Laboratory of the Chamber of Mines of South Africa. CSIR joined the search for answers, with Evert in the lead. So began his career in Rock Mechanics/Engineering. This period is described in the Preface [2] of his book “Practical Rock Engineering”. It was at this time, in his own words, that he “stumbled into” rock mechanics.

Evert had a great ability to identify the major technical issues and questions facing contemporary industry. This informed the research areas that he and his research groups worked on in South Africa, in the UK and later in Canada, all to the great benefit of the local and international mining and civil engineering industries. Although, as evidenced by his PhD thesis and his early series of papers published in the SAIMM Journal, he was well able to solve more complex and difficult analytical problems, his published solutions tended to be as simple and as clear as possible. and oriented to practical issues. This may have been what caused so much of his work to be readily adopted in industrial practice. In both South Africa and at Imperial College, London, he developed a range of effective laboratory and field test equipment. This again reflected his clear engineering thinking, but also, perhaps, his early education and training in mechanical engineering.

Evert was a master communicator in both the written and spoken word. He was always able to give extremely clear keynote lectures and other presentations without the assistance of notes¾and, unlike so many of our colleagues, to conclude on or before the expiry of the allotted time! This characteristic was still very much in evidence when he spoke at a colloquium held in Brisbane, Australia, to mark Ted Brown’s final retirement on 4 December 2018, by which time he was about 85 years of age. His ability to illustrate technical points with clear, beautifully drawn sketches added to the power of his technical communications. We understand that his first wife, Theo, helped him with some of his drawings, but this doesn’t detract from Evert’s skill in this regard.

Hoek’s Corner [3] established by Rocscience in 1996, gave Evert the opportunity to prepare and present a series of videotaped lectures. These are all excellent, major contributions to rock engineering practice. (see e.g. the 341p. “Practical Rock Engineering”) and, together with many of Evert’s numerous publications, are available free to the rock mechanics/ engineering community on the website. This allows everyone in rock mechanics/engineering to continue to benefit from the work of this truly major figure in our discipline. He worked as a consultant on close to 40 major rock engineering projects in many countries around the world (see e.g. Hoek’s Corner “Design Challenges, Disasters and Lessons in Rock Engineering”[4].

As shown in the table below, Evert has been recognized for his contributions by more awards than anyone in the field, from major organizations associated with rock mechanics/engineering. His lecture in 2021 “Developments in rock engineering from 1958 to 2020” [5] his last general presentation, is also essential reading for everyone in rock mechanics/engineering. Clearly, he recognized that computer models are now making valuable contributions to important engineering problems and welcomed these developments.

Evert at Malpasset Dam site (ca 1970)

Tour led by Pierre Londe (PL) (France), the leading authority on the collapse.

H. Kutter, Post Doc. with Dr. Hoek, Imperial College; Ph.D. (1967) University of Minnesota.

It was the collapse of the Malpasset Dam on the Reyran River (France), on 2 December 1960, that led Prof. Leopold Müller (Austria) to establish the International Society for Rock Mechanics in Salzburg, Austria, May 24 1962.

Dr. Evert Hoek – (Aug 23, 1933 –July 6, 2024) Achievements, and International Recognition

1933 Born in Southern Rhodesia (now Zimbabwe) Parents were Farmers.

1951 Enrolled University of Cape Town, South Africa 1955 B.Sc. (Mech. Eng); (1957) M.Sc. (Mech. Eng.)

1958 Research Engineer CSIR (Council for Scientific and Industrial Research), Pretoria

1965 Ph. D. University of Cape Town

1966 Reader in Rock Mechanics; 1970, Professor of Rock Mechanics, Royal School of Mines, Imperial College, London

1975 Senior Associate, Principal, Golder Associates, Vancouver

1987 Industrial Research Professor in Rock Engineering. University of Toronto

1993 Independent Consultant, Rock Engineering in Civil & Mining Engineering

2018 Retired, Vancouver

See also: Hoek’s Corner [6], Preface to the book “Practical Rock Engineering” [7] and Wikipedia [8].

Honorary Doctorates

1994 University of Waterloo, Canada (D.Sc.)

2004 University of Toronto, Canada (D.Eng.)

2016 Polytechnic University of Catalonia, Barcelona, Spain

Awards

1970 Consolidated Goldfields Gold Medal, UK

1975 AIME Rock Mechanics Award, USA

1979 E. Burwell Award, Geological Society of America

1982 Sir Julius Wernher Memorial Lecture, UK

1983 Rankine Lecture, British Geotechnical Society

1985 Gold Medal, Institution of Mining and Metallurgy, UK

1991 Müller Award (First), International Society of Rock Mechanics

1993 William Smith Medal, Geological Society, UK

1993 Fellow, Royal Academy of Engineering UK

1998 Glossop Lecture, Geological Society, UK

2000 Terzaghi Lecturer, American Society of Civil Engineers

2001 Fellow, Canadian Academy of Engineering

2006 Member, US National Academy of Engineering

2008 Kersten Lecture, Univ. Minnesota

Lifetime Achievement Awards

2018 AITES (International Association of Tunnelling and Underground Space) [9]

2021 Rocscience Lifetime Achievement Medal. First Rocscience International Conference (April 21-22, 2021) [10]

2021 “Developments in rock engineering from 1958 to 2020” Q&A after Lecture [11].

How did Evert view future developments in Rock Mechanics/Engineering?

In 2018, Evert gave an interview to the ASCE Journal GeoStrata [12]. The article provides insights into Evert’s views on developments and prospects in Rock Engineering, and advice for engineering students just starting their careers in rock mechanics/engineering. This is recommended reading.

He was optimistic that consulting groups would soon provide computer programs that would provide civil, mining, and geological engineers involved in underground projects, with valuable practical design assistance. Evert expressed concern in the article that current university programs in these disciplines were not providing students with an awareness of the real situations that they may encounter underground and how to apply information from their studies appropriately in practice.

To overcome this shortcoming, especially for students considering graduate studies, he urged (See Geo-Strata. p.41) “Get out there! Take a break from school and get into the real world.” … He repeats this advice in the final one and a half minutes of his 2021 Lecture “Developments in Rock Engineering from 1959 to 2020” [13].

In answering the question “How will the methods and practices you’ve developed adapt with advances in technology?” (Geo Strata p.38), he comments on the Hoek-Brown (H-B) Criterion with GSI: “While I consider this method to be crude, it has been widely adopted and used because of the lack of suitable alternatives”.

The Geological Strength Index (GSI) — the extent to which the intact rock strength should be reduced due to fracturing and related in situ conditions — is based on an assessment by the rock engineer and/or field geologist at the site, using a guide established and modified by Dr. Hoek and colleagues over many years. This direct involvement of field personnel in the assessment is undoubtedly part of the attraction of the H-B Criterion. It will be interesting to see how effectively numerical models will be able to replace this criterion.

Rock as it exists in the ground is certainly not the same as the refined materials — many derived from this rock — used in various other branches of engineering, and its behavior over the period involved in practical rock engineering is more difficult to define. It does have the properties of elasticity, plasticity and viscosity that allow the rock to respond to applied loads — and it does obey Newton’s Laws — but it has been evolving for over 4 billion years! Although it took around 2 billion years for temperatures to drop sufficiently to allow solid rock to form — and Continental Drift, Plate Tectonics, Mountain Building, Faulting, Erosion, Ice Ages, etc. to become active — these processes have been at work for a very long time. Mining has been practiced for over 40,000 years [15]. Throughout most of history, mining technology has developed empirically. Newton’s Principia appeared in 1687. The first book in English on the “Theory of Elasticity” [16] was published in 1934. It was not until the early 1950’s that rock mechanics was formally identified as a discipline, and attempts were first

made to apply Newtonian mechanics to this complex material rock. Advances in computing, together with field experience, over more than the past six decades, are now starting to reveal valuable design approaches, but challenges remain.

Several colleagues with a sound understanding of modeling in rock have noted that numerical modeling in rock engineering involves issues not often encountered in other engineering disciplines. For example,

“Data-limited problems [such as in rock mechanics] require a very different modelling approach from that developed in, for example, electrical or aerospace engineering and it follows that one cannot use models in rock mechanics in a conventional way, and that there is a need to adopt a distinctive and appropriate methodology in rock mechanics modelling” [17].

“We are at the beginning of multi-scale science and multiscale computation, with a growing need to understand not only phenomena on each of many scales, but also the interaction between phenomena at very different scales” [18].

Evert recognized these challenges and, as is clear from his 2021 lecture (discussed below) he felt that computer programs to address them are now becoming available from consulting groups. So, how can ISRM move these developments forward?

For the first time in many decades the importance of minerals and improved mining technology, availability of powerful computer and allied systems, and development of the subsurface in general, to the future well-being of the planet and its inhabitants are being recognized by groups not traditionally associated with mining, e.g. World Bank (2017), International Energy Agency (2020).

Professor Brad Ross, University of Arizona USA [19] considers that minerals and mining are so central in this century, and the professional attributes required of mining engineers are such that a special Global Academy is needed (analogous to Military Academies in some countries) serving the mining industry world-wide.

Several parts of the world, especially mineral exporting countries (e.g. Australia, Canada, Chile, China (PRC), Eastern Europe, South Africa) have made, and are making, important contributions to mining technology, and reduction of adverse environmental impact. ISRM is well placed to stimulate awareness of and draw attention to these developments, and stimulate mining innovation in research universities, especially as leading mining companies are now developing their own applied research groups and require interdisciplinary teams of engineers.

Climate Change is a major threat to life on Planet Earth. It is primarily an above-ground issue, and subsurface engineering has a major role to play to adapt to it and provide protection to the public from the more extreme effects.

Civil engineers will find stimulating examples of subsurface applications in the book “Sweden Underground; Rock

[Note. The June 2024 ISRM Lecture by Prof. Carranza -Torres [14] provides a detailed update of the HB criterion i.e. the strength of the intact rock under all combinations of loading. (The ISRM Lecture does not address the GSI - except in citing a practical application at the end of the Lecture)]

engineering and how it benefits Society” (2018) [20]. An earlier (1988) book “Going Underground” by the Royal Swedish Academy of Engineering Sciences IVA (194 pages) contains a wealth of examples of subsurface engineering. Although now out of print, a digital copy may be downloaded free of charge, courtesy of IVA [21]. The motivation for the book is described by IVA President Hans Forsberg on p.9 of 194.

It is worth noting also that Sweden, a neutral country during the USA USSR Cold War (1947 to 1992), was concerned that any outbreak of hostilities could result in nuclear fallouts and other adverse consequences for Sweden. Development of underground facilities that could be incorporated into the daily life of communities (e.g. subways, concert halls, shopping malls) could provide shelter in an emergency without causing panic.

Exploration of Outer Space, a major international R&D emphasis since the 1960’s, has yielded life-changing benefits for the world. It is now critical to pay comparable attention to the benefits of Inner Space, the world beneath our feet¾and for ISRM to stimulate and draw international attention to the opportunities, the challenges and the global urgency of Exploration of Inner Space!

C. Fairhurst and E.T. Brown ISRM Past Presidents

[1] https://www.klasslooch.com/leon_commission_of_inquiry.htm

[2] https://static.rocscience.cloud/assets/resources/learning/ hoek/1.-Preface.pdf (pp 3-13)

[3] https://www.rocscience.com/learning/hoeks-corner

[4] https://www.youtube.com/watch?v=wji5zK7c1Qo&t=36s

[5] https://www.youtube.com/watch?v=dy83dYaXHVY&t=5s

[6] https://www.rocscience.com/learning/hoeks-corner-rockmechanics-reference-library

[7] https://static.rocscience.cloud/assets/resources/learning/ hoek/1.-Preface.pdf

[8] https://en.wikipedia.org/wiki/Evert_Hoek

[9] https://www.youtube.com/watch?v=ne3Xa9knhzQ

[10] Introduction by Dr Yacoub, CEO, Rocscience; Tribute to Dr Hoek by Dr Curran, Founder Rocscience. Lecture by Dr. Hoek.

https://www.youtube.com/watch?v=dy83dYaXHVY&t=5s.

[11] https://static.rocscience.cloud/assets/resources/learning/ hoek/RIC2021-QAwithDrHoek_V2.pdf

[12] https://cgs.ca/pdf/Evert_Hoek-GeoStrata_May_Jun_2018.pdf

[13] https://www.youtube.com/watch?v=dy83dYaXHVY&t=5s

[14] https://isrm.net/page/show/1740

[15] The Ngwenya Mine in Eswatini (formerly Swaziland) is the world’s oldest mine. First operated in 42,000 BP, it was designated a UNESCO World Heritage site in 1982

[16] S. Timoshenko. 1934, McGraw Hill

[17] Int. J. Rock Mech. Min Sci.& Geomech. Abstracts. Vol.25 June 1988, pp.99-106

[18] Alexandre Chorin (2008) Foreword (p. x) to the book “Scaling” by G.I. Barenblatt, Cambridge Univ. Press. First Edition (171p)

[19] https://mining.arizona.edu/person/brad-ross-phd-pe

[20] https://www.befo.se/publikationer/sweden-undergroundrock-engineering-and-how-it-benefits-society/

[21] https://itasca-downloads.s3.amazonaws.com/ Going+Underground.pdf

Evert (right) and E.T. (Ted) Brown (left) at Dr Brown’s Retirement Dinner, Brisbane, 4 Dec 2018

Evert (right) and Charles Fairhurst (left). ARMA (American Rock Mechanics Association) Annual Meeting San Francisco, June 2017

ISRM SCIENTIFIC FAREWELL TO DR. EVERT HOEK

Contributions of Dr. Evert Hoek to Rock Mechanics and Rock Engineering:

“From intact rock to rockmass strength and practical rock engineering approaches”

This article puts forward some of the most relevant contributions of Dr. Evert Hoek to rock mechanics and rock engineering. It synthetized the talk presented by the author in a session of tribute to Dr. Hoek achievements in the 1st International Rock Mass Classification Conference (RMCC)

hold in Oslo, Norway, on October 30-31, 2024, invited by the President of the ISRM, Seokwon Jeon.

Design of engineering structures requires knowledge of the response of materials to anticipated loading conditions. In rock engineering, the materials of interest are in situ rock masses comprised of intact rock and discontinuities. In founding the ISRM in 1962, Professor Leopold Müller identified inability to determine the strength of a rock mass as the most important obstacle to progress in rock mechanics. In his own words (Müller, 1963): “Describing the construction material, the rock mass, in its condition and its behaviour is the first task… to safely lay out, sensibly construct…, and economically execute works in rock”. As an example of a problem that cannot be solved at the time, Prof. Müller referred to the case of a slope in a rock mass as depicted in Figure 1.

Hoek and Brown had the foresight to recognize that a rock mass failure criterion has no practical value unless it can relate the strength of intact rock and rock masses using geological observations in the field. The author tried to trace back how Dr. Evert Hoek, together with Ted Brown, could eventually propose a criterion that was capable of going from

Fig. 1 - Example of the problem of a slope where knowing the strength behaviour of the rock mass was the pre-requisite to solve the problem. The sketch illustrates the three phases of the progressive failure of a rock slope, according to Müller (1963): (a) opening of tension cracks at the top of the slope; (b) disentanglement of the massif in the rupture region and stress concentration at the toe and (c) rupture at the foot of the slope.

Fig. 2 - Strength estimate of a sample containing two pre-existing discontinuities according to their orientation. Combined strength results and potential final strength response.

the intact rock strength to that of the rock mass. It seems that they first studied the results of tests on fissured samples (typically cement or engineered materials) carried out by different researchers at the late sixties, as Dr. Hoek later recognized (Hoek, 1983). Dr. Hoek acknowledged that for jointed rock masses, an evaluation of shear strength presented formidable theoretical and experimental issues. However, since this question was of fundamental importance in almost all major designs involving foundations, slopes or underground excavations in rock, it was essential that such strength estimates could be made and that these estimates should be as reliable as possible.

They started building on the original and modified versions of Griffith criteria, which showed in the form of a parabolic Mohr envelope. Then they observed the noticeably curved trends of strength results in tests on samples with different fractures patterns, noticing how the strength response of the sample were generally over the simple frictional response of a sample with transversal joint but below the parabolic line representing the strength of the intact material.

Then Hoek & Brown looked to results of the strength of samples with a single pre-existing discontinuity as described by Jaeger (1960), i.e. the so-called Jaeger’s weaknessplane strength theory, and then to those of results with two differently oriented discontinuities, in line with results presented by John (1969) or Ladanyi & Archanbault (1972). To attempt to predict the behaviour of a jointed rock mass containing several sets of discontinuities, they try to superimpose a number of analyses for individual discontinuity sets, in the hope that the overall behaviour pattern obtained would be representative of the behaviour of an actual jointed rock mass (Figure 2). The strength of a rock sample containing a single joint is highly anisotropic. As more joints of similar

shear strength are included at different orientations, strength of the sample becomes less anisotropic. The assumption of isotropy is considered reasonable for rock masses containing four or more such joint sets (Hoek and Brown, 1980).

Results of strength models with intermittent joints (Brown, 1970) and an estimate on their strength based on the part of failure occurring through joints and taking place through intact material probably help the authors to have a first estimate of strength. The experience accumulated by Dr. Hoek on the strength of intact, and different weathered Panguna andesite samples, when consulting for an open pit mine (Hoek & Brown, 1980) allowed them to propose their relevant failure criteria both suitable for intact rock and the rock mass. It is though relevant note that ultimately, the process used by Hoek & Brown in deriving their empirical failure criterion was one of pure trial and error. Apart from the conceptual starting based on Griffith theory, there was no relationship between the empirical constants in the criterion and any physical rock feature. The justification for choosing this criterion over the many alternatives just lied in the good predictions provided, and its convenient application to typical rock engineering problems. The foundational problem of the ISRM was solved for good, or not?

May be not, since in 1994, Dr. Evert Hoek (1994) wrote the following words in a letter to the editor of the ISRM News Journal: “In writing Underground Excavations in Rock almost 15 years ago, Professor E.T. Brown and I developed the HoekBrown failure criterion to fill a vacuum which we saw in the process of designing underground excavations. Our approach was entirely empirical, and we worked from very limited data of rather poor quality. Our empirical criterion and our estimates of the input parameters were offered as a temporary solution to an urgent problem”. He continued: “In retrospect, it is clear that we were naïve in believing that our emergency criterion would soon be replaced by a set of well-researched predictive tools which were well substantiated by field studies and back analyses of real rock engineering case histories. In fact, the reverse has happened, and I am alarmed to see the Hoek-Brown criterion being applied to problems which we did not even dream about when we made those desperate estimates 15 years ago”.

Anyhow, the analysis of these tests results guided Hoek and Brown to solve one of the most relevant problems in rock mechanics at the time: “Moving form laboratory to the engineering work scale”, even if in an estimative manner. This approach was fine-tuned later with the development of GSI, even if still one has to be careful when applying this now popular approach.

Additionally, Dr. Hoek developed highly relevant contributions on how to solve actual problems at a "practical" engineering level, which are well illustrated in the chapters of the notes by Dr. Hoek (2023): "Practical Rock Engineering". The practical focus of Dr. Evert Hoek’s approach to rock engineering was enormous, especially in topics such as "When is a rock engineering design acceptable?" or "A stability problem in Hong-Kong" where he provided real geotechnical meaning to a simple formula, using it in different ways to give practical answers to the real problems raised.

Fig. 3 - Dr. Hoek in talk delivered in the 1992 meeting of the Spanish National Group of the ISRM, SEMR, in Madrid, Spain.

He was well aware the there was no unique factor of safety or probability of failure or coefficient of reliability or whatever number one wants to use that it is generally applicable in rock engineering. Every structure has its own set of problems and he recommended looking at it based on its own merits. Indeed, as he often stated, the ultimate responsibility lies with the engineer and it cannot be hidden in a set of calculations or factor of safety estimate procedure.

Did we know the strength of the rock? For intact rock tested in the laboratory, yes, for a rock mass, no. This is what we needed to determine and this is why we needed an International Society for Rock Mechanics. This is what Dr. Hoek helped us to solve, and so as a Society we should be eternally grateful!

Leandro R. Alejano

ISRM VP for Europe 2015-2019

Brown ET (1970) Strength of models of rock with intermittent joints. J. Soil Mech. Found. Div., ASCE, Vol. 96, SM6, 1935-1949.

Hoek E (1983) Strength of jointed rock masses. Geotech 23:187–223.

Hoek E (1994). The challenge of input data for rock engineering. Letter to the editor, ISRM News Journal Vol. 2, N. 2. Int. Soc. Rock Mechanics.

Hoek E (2023 ed.) Practical Rock Engineering. https://www. rocscience.com/learning/hoeks-corner

Hoek E, Brown ET (1980). Underground Excavations in Rock. London: The Institution of Mining and Metallurgy.

Jaeger JC (1960) Shear failure of anisotropic rocks. Geol Mag. 1960;97:65–72.

John KW (1969). Festigkeit und Verformbarkeit von drückfesten, regelmässig gefügten Diskontinuen. Univ. of Karlsruhe.

Ladanyi B, Archambault G (1972). Evaluation de la résistance au cisaillement d’un massif rocheux fragmenté. Proc. 24th Intnl. Geol. Cong., Montreal. Sect. 130, 249-260.

Müller L (1963) Die Standfestigkeit von Felsböschungen als spezifisch geomechanische Aufgabe. Felsmech. u. Ing. Geol., 1, 50-71.

IN MEMORY OF

JUN SUN

1926-2024

Sun Jun was an expert in underground construction and tunnel engineering and an academician of the Chinese Academy of Sciences, who served as president of the Chinese Society for Rock Mechanics & Engineering from 1994 to 1998.

Though his ancestral home was at Shaoxing, Zhejiang Province, he was born in Suzhou, Jiangsu Province. He graduated from the Department of Civil Engineering of Shanghai Jiao Tong University in 1949. After University in 1949, he became a technician from the East China Airlines and Public Housing Management Office in Shanghai. After a year as a teaching assistant at Jiaotong University between 1951 and 1952, he moved to Tongji University, where he successively served as a lecturer, associate professor, deputy director of the Department of Underground Engineering, director of the Academic Affairs Office, professor, head of the Department of Structural Engineering, honorary head of the Department of Underground Building Engineering, member of the School Affairs Committee, and vice chairman of the School Academic Committee. From 1980 to 1981, he was a visiting professor at the North Carolina State University. He was a member of the Chinese Academy of Sciences (CAS) since November 1991 and Fellow of the International Society for Rock Mechanics (2015).

ISRM owes Professor Sun a lot for his enormous and constant dedication to the Society during many years, as the Vice President at large from 1995 to 1999. Professor Sun's lifelong commitment to teaching, research, and engineering applications in geomechanics, tunneling, and underground engineering has left an indelible mark on our community. His leadership and contributions will be remembered with deep respect and gratitude.

ISRM MEMBER’S VIEWS

The ISRM Board started a series of actions to enhance members engagement. Besides the establishment of a committee specifically dedicated to this objective, it also pretends to carry out more initiatives, such as the talk delivered by Vice-President Muriel Gasc-Barbier at the Early Carrier Forum in New Delhi, that is presented herein. The word talk was chosen intentionally, as it is a personal view of her own engagement with rock mechanics along her life.

FEMALE AND MOTHER IN AN ENGINEERING ENVIRONMENT

Dear participants of the Early Career Forum, Here I am, in front of you to speak about a non-scientific subject which I should know very well but I don’t like to speak about: myself. I took time before accepting Ki-Bok’s invitation as I don’t see myself as a role model or an example to be followed. But as my experience grows every year, I thought I had to accept this kind invitation. I won’t speak for all women because I think that each of us has to follow her own path, considering her own skills, her own strength, her own fears and creating her own opportunities. I will just explain you my own path.

I am just over 50, married for 26 years and the mother of four children who are now 24, 22, 20 and 17 years old.

I graduated as a geophysical and geotechnical engineer in 1996. I worked as a geotechnical engineering in different companies during 2 years and then I was hired as a research engineer in a research laboratory dedicated to identify and study a proper host rock for the French waste repository. Thus, there, I had the opportunity to prepare my PhD thesis on “Study of deformation mechanisms in deep clayey rocks: Contribution of microstructure and petrophysical analyses”. It was mainly an experimental research to understand the chemo-, hydroand hygro-mechanical coupling as well as creep behavior. I defended it in 2002. In the meantime, I got married (in 1998) and we had two babies, the eldest in 2000 and the second in 2002. In fact, I took advantage of my maternity leave to write my PhD thesis as I had not a lot of time during office hours considering the engineer work.

My PhD director is now retired, but even in the last days of his working time, 20 years after this period, he was still presenting me as his only student that has two babies during her PhD. And in fact, if I didn’t think it could be a problem I should confess that I would probably be not very happy if one of my female students tell me she is pregnant. But in the meantime, if a male student has babies during his PhD who would see it as a problem? I should also confess that it was hard years with short nights, a lot of work at home and at the lab.

Then my husband and I decided to move from Paris and its exhausted and expansive life to another location. As I was the most specialized, we supposed it was more difficult for me to find a job, so together we decided that I had to find a job and my husband will look for one once arrived. We moved to Toulouse with a third to born baby. My father-in-law who was a very nice man and a great scientist told my husband that it was not the proper way to do: a wife had to follow her husband not the other way around.

So by the age of 30 I had 3 children, a PhD and a new job in a new town 700 km far from ours families. And it was probably the first time I really realized that being a woman and being a man at work was not the same.

Obviously, in France at least, women have the same rights as men. But in practice, there are always differences. At the hospital, if you see men and women in white coats, instinctively you'll think that the men are the doctors and the women the nurses. At work it was the same. If a deliveryman arrived, he wouldn't stop at the first 3 offices in the corridor (men's), but would come all the way to the 4th, mine office, systematically thinking that I was the secretary. The older I got, the less this happened. Likewise, when you're a woman, even at work, some men - not all, fortunately - consider that you know nothing

of organization (I’m lucky, my husband works in logistics) we had to organized our dairy, mixing in the best possible way, meetings, travels, symposium, and children’s activities. I don’t want you to think we lived in wonderland. we had our moments. I also had to fight hard sometimes against some colleagues or directors who didn’t understand my purpose. But I also found support in others, and of course, in my husband. But the most important is the satisfaction of the achievement that fuels your next results: knowing you can do it once, gives you strength to do more.

I might not be THE best scientist in my field, I don’t have the largest number of scientific papers, and I am not known worldwide. But I never wanted to be THE best scientist. I only wanted to give MY best, and at the same time, keep the right balance between personal and professional life. And I did it quite well I think: I do have some contributions to rock mechanics and rock engineering, I wrote some interesting papers and I also was the youngest to be appointed senior researcher (and I still am) among my ministry research staff. And, moreover I still have more than 10 years to work.

about maths or mechanics. I again changed jobs 7 years ago. When I arrived in my new one, I had a few projects in the pipeline. I went to see a colleague in charge of a team of a dozen engineers (all men) and suggested that he take part in the project. He rejected everything I proposed. In the end, I set up the project without him, and … I got the funding. I don't think he gained anything by behaving like that. But, as I said, some men are like that. They're not the majority, but they're the loudest. As a woman, if you're successful, there's always someone who'll tell you that you weren't chosen for the value of your work, but to be the female guarantor of this or that institution. If a man has character, it's a good thing as he knows how to assert himself. If a woman has character, at best she's a b…, at worst she's hormonal.

In France, civil servants are not so well paid. Thus, we never were able to afford fulltime housemaid. We relied on nursery and elementary school for our children. At home, I cook every day, I go to the supermarket and my husband do most of the rest of housekeeping. For those of you who think that my husband is weak, I can tell you are completely wrong. He has his own job and must travel in different countries because of it. But He / we decided that my job was as important as his. So, when the children were younger, well, it was mostly a question

As a conclusion, I can only share an advice to you all: and then, you will do what you want or can. To you, young ladies, my situation might not be transposable to yours, because our countries are different, the uses and the era are different (I don’t forget that I gave birth 24 years ago! And I probably could be your own mother). And I can’t ignore the weight of traditions in our societies. But if you think you can do it, just do it, don’t wait than just another guy takes your place. If you don’t believe in your dreams, who will? You will probably have to work harder than men, but ‘Yes you can’.

And now, to the young men (and maybe also to the not so young…) that have come to listen to this session, think cooperation more than competition: remember that lowering a colleague (men or women by the way) never helps to get the better out of your colleagues. When you are confident on your abilities, you don’t need to lower the others. And it’s a sign of respect and strength to be able to support those who need it.

I can’t finish without quoting the father of this nation which is hosting this conference, and a great man by itself. In his autobiography, “The Story of My Experiments with Truth,” Gandhi wrote, “To call woman the weaker sex is a libel; it is man’s injustice to woman. If by strength is meant moral power, then woman is immeasurably man’s superior”.

Muriel Gasc-Barbier ISRM Vice-President for Europe

FORTHCOMING

ISRM SPONSORED CONFERENCES

2025 16-20 June

2026

Eurock 2025: Expanding the undergroung space. Future development of the sub-surface –the 2025 ISRM International Symposium Trondheim, Sweden

27-01 April-May LANDSLIDES 2026: Landslide Geo-Education and Risk (LAGER) - an ISRM Specialized Conference - co-hosted by the FedIGS JTC1 and JTC3 Queenstown, New Zealand

26-28 August LARMS 2026: X Latin American Congress on Rock Mechanics - an ISRM Regional Symposium Brasilia, Brazil

15-19 September Eurock 2026: Risk management in Rock Engineering - an ISRM Regional Symposium Skopje, Macedonia

13-16 October JTC2 Conference: 6th International Conference on Information Technology in Geo-Engineering - an ISRM Specialized Conference Oslo, Norway

26-29 October Slope Stability 2026 - Slope for safety performance Lima, Peru

22-26 November ARMS 14: Rock Mechanics for the Next Generation – Innovation and Resilience - the 2026 ISRM International Symposium Fukuoka, Japan

17-23 October 16th ISRM International Congress on Rock Mechanics Seoul, Korea

2027

The ISRM holds International Congresses on Rock Mechanics and Rock Engineering, at four year intervals, on themes of general interest to the majority of the membership, and sponsors a co-ordinated program of International Symposia, Regional Symposia and Specialized Conferences organised by National Groups of the Society.

The annual ISRM International Symposium is chosen from the ISRM Regional Symposia that take place in that year and is the venue for the annual meetings of the Council, Board, and Commissions of the Society. ISRM Specialized Conferences are events of a smaller nature, usually focused on a specific theme.

National Groups seeking to host an ISRM Regional Symposium or Specialized Conference shall submit a written proposal to the Secretariat. Their organization is ruled by By-law No. 5, and application forms are included in specific Guidelines prepared by the Board, and available on the ISRM website (https://www. isrm.net/conferencias/submit.php?show=conf).

Proceedings of ISRM conferences are stored in the ISRM digital library available in the OnePetro platform (onepetro.org).

REPORTS OF ISRM CONFERENCES

2024 ISRM INTERNATIONAL SYMPOSIUM AND ARMS13

New Delhi, India

The ISRM International Symposium 2024 and the 13th Asian Rock Mechanics Symposium (ARMS13) was organized during September 22-27, 2024, in New Delhi, India, with the main theme “Advances in Rock Mechanics-Infrastructure Development”. The symposium was a joint effort of the Indian National Group of ISRM, the Central Board of Irrigation and Power (CBIP), New Delhi, and IIT Roorkee, India.

Pre-symposium events were held on September 22 and 23, 2024, which included three short courses and four workshops focusing on the latest developments in the field of Rock Mechanics. The short courses organized were: (i) Numerical Analysis with FLAC2D/FLAC3D, (ii) Rock Mechanics in Tunnelling Techniques, and (iii) Enhancing Tunnelling and Rock Slope Engineering with Rocscience Software Tools. The workshops covered: (i) Smart Mining and Rock Engineering, (ii) Rock Grouting, (iii) Integrating Rock Mass Classification Techniques and Tunnelling Technology, and (iv) Rockfall Protection and Landslide Stabilization Solutions Integrated with IoT. Simultaneously, meetings of the ISRM Board (22nd, Sept), ISRM Council (23rd Sept), and various commissions were held, which featured the Commission on Bio-Rock Mechanics, the Commission on Rock Grouting, and the Commission on Testing Methods. The Asian Council Meeting took place on 25th September 2024.

The symposium was officially inaugurated on the morning of September 24, 2024, followed by the Rocha Medal Award Ceremony, where K. Sawayama (Japan) received the prestigious honour. The event continued with the 2024 Franklin Lecture, delivered by Prof. Vikram Vishal from IIT Bombay, India. The inauguration saw the participation of over 300 attendees, while approximately 150 authors from more than 20 countries registered for the conference.

A special session was dedicated to honouring the memory of the late ISRM President, Dr. Eda Quadros. Dr. Nick Barton shared his personal recollections in a heartfelt talk, “Personal and ISRM memories of 30 years with Eda”, followed by presentations from Prof. Sérgio Fontoura (Brazil) and Dr. Luís Lamas.

Technical proceedings were held over three days, from September 24-26, which included oral presentations, poster presentations, and plenary sessions. The plenary sessions featured nine keynote lectures and corporate presentations, while the technical sessions were divided into four parallel sessions in the afternoons. A total of 196 technical papers (116 oral and 78 poster) were presented, spanning six themes namely: Theme-A: Site Investigations and Characterization of Rocks & Rock Masses; Theme-B: Analytical, Numerical and Constitutive Modelling; Theme-C: Advancement in Laboratory Testing Techniques; Theme-D: Drilling, Blasting and Slope Stability; Theme-E: Rock Supports and Instrumentations, and, Theme-F: Tunnelling, Underground Space and Storage.

ISRM Board members with organizers

Council meeting

The symposium also featured the Early Career Forum (ECF), organized by a committee constituted by ISRM. The ECF invited eight rock engineers, all under the age of 38, from Asian neighboring countries, offering them full registration and covering their travel and accommodation expenses through ISRM’s EFC. The participants included researchers from Bangladesh, India, Mongolia, Malaysia, Kazakhstan, and Nepal.

An interesting event for the students was the Rock Bowl Competition. The Rock Bowl Competition was held on September 24 and 25. The event was inaugurated by Prof. Sérgio Fontoura from Brazil. Two teams were awarded cash prizes of INR 1,00,000 and 50,000, respectively.

A cultural program and banquet dinner was organized in the evening of 25th September. The cultural program depicted vibrant cultural diversity of India through various dance performances from different parts of the country. Before cultural program, prominent Indian experts who have contributed to the field of Rock Mechanics, were felicitated by ISRM India. Award ceremony was also held by the ISRM for: a) John Hudson Rock Engineering Award, b) Science Achievement Award, c) Young Rock Engineer Award, d) Rock Bowl Awards, and e) ECF Certificates.

Closing Ceremony was held on 26 September at 15:45 hrs. ISRM best paper awards were given for General and Young category for the best papers presented during the symposium. Farewell speeches were delivered by Chair Scientific committee and VP Asia. The Symposium has been extremely successful, and the ISRM president congratulated the organisers for the great success. The ISRM President also conferred on the Chairman Scientific Committee, a Certificate of Appreciation for excellent organization of the ISRM International Symposium-ARMS13. Finally, the symposium was declared closed by the ISRM President.

EUROCK 2024

Alicante, Spain

The European Rock Mechanics Symposium (EUROCK 2024) was held from July 15 to 19, 2024, at the University of Alicante, Spain. Organized by the University of Alicante with the support of the Spanish Society for Rock Mechanics (SEMR), the event brought together nearly 300 international experts from 40 countries and all five continents to discuss advancements and challenges in rock mechanics and related engineering fields.

The symposium program featured thematic sessions with more than 176 oral presentations, three training workshops, and two technical excursions, covering a broad range of relevant topics, including:

• Rock properties, testing methods and site characterization

• Rock mechanics for infrastructures

• Mining rock mechanics and rock engineering

• Design methods and analysis

• Rock mechanics for heritage

• Geophysics in rock mechanics

• Numerical modelling and backanalysis

• Monitoring and backanalysis

• Underground excavation and support

• Risk and hazard

• Applicability of EUROCODE-7 in rock engineering

• Geomechanics for the oil and gas industry

• Ores, building and industrial rocks

• Application of artificial intelligence to problems of rock mechanics

• Remote sensing in rock mechanics

• Geothermal technology

• Rock Mechanics education and training

The event included keynote lectures by renowned experts who shared their latest research and developments:

• Dr. Eduardo Alonso, Spain. Heave of anhydritic claystone. Dealing with spatial heterogeneity

• Dr. Michel Jaboyedoff, Switzerland. Toward the assessment of the rockfall sources hazard failure using 3D point clouds and remote sensing techniques

• Dr. José Muralha, Portugal. Shear strength of rock discontinuities: from field investigations to design parameters

• Dr. Andrea Segalini, Italy. Practical challenges in designing monitoring systems in rock masses: from parameters selection to data elaboration and management

• Dr. Philippe Vaskou, France. Embedding structural geology in all rock engineering projects: wishful thinking or future reality?

Additionally, poster sessions and networking opportunities provided a platform for professionals and researchers to foster collaboration.

During the closing ceremony, PhD student Carlota Rodriguez San Miguel from Luleå University of Technology (Sweden) received the award for the best young scientist oral presentation, titled “Small scale experiments for contourboreholes blast”.

The symposium proceedings were published in a book edited by CRC Press (DOI: 10.1201/9781003429234) and will be available for ISRM members in the online library OnePetro after a two-year embargo.

ISL2024

Chambéry, France

ISL (International Symposia on Landslides) is a quadrennial event organized under the patronage of the Joint Technical Committee on Natural Slopes and Landslides (JTC1) of FedIGS.

After Kyoto 1972, Tokyo 1977, New Delhi 1980, Toronto 1984, Lausanne 1988, Christchurch 1993, Trondheim 1996, Cardiff 2000, Rio de Janeiro 2004, Xi'an 2008, Banff 2012, Napoli 2016, and Cartagena 2021, ISL2024 was the 14th International Symposium on Landslides and it was hosted in France, in Chambéry, from 8 to 13 July 2024.

The symposium gathered 316 participants from 37 different countries of the five continents. Fifty students took part in the ISL2024 and 9 attended the summer school.

The symposium program included nine keynote lectures and 12 parallel sessions in 2 rooms, organized in 11 topics: multiscale constitutive modelling for soils and rocks; weathering effects on soils and rocks destabilization; permafrost and ground stability; survey techniques; modelling of soil and rock hazards; recent progress in numerical tools for landslide modelling; risk analysis and mitigation; modelling and design of protective structures; artificial intelligence and machine learning techniques applied to slope engineering; make researchers, authorities and companies working together and involve inhabitants; case studies. One hundred and twenty scientific talks were given. A hundred posters were presented, and two prizes for the best poster were awarded. The first keynote lecture was the Albert Heim Lecture selected by JTC1 and awarded to Jordi Corominas Dulcet, Emeritus Professor of Engineering Geology at the Polytechnic University of Catalonia.

Half a day of technical visits were organized to landslide and rockfall sites: Harmalliére, Avignonet and Tarentaise:

The symposium was preceded by a 2-day summer school attended by 13 students from seven countries dedicated to landslides and rockslides from hazard to mitigation, that included a half-day of technical visits to landslide and rockfall sites close to Chambéry.

A post-conference tour was also organized by Prof Loew in the Swiss Alps with 17 international guests and two guides. All aspects of landslide research and applications were discussed: predisposition, movement mechanisms, longterm causal factors, triggers, impacts of climate change, landslide monitoring and early warning, landslide hazard/risk management in Switzerland.

5TH ICITG

Golden, Colorado USA

The 5th International Conference on Information Technology in Geo-Engineering (5th ICITG) was held in Golden, Colorado, USA from August 5 to 8, 2024. The conference, organized by JTC2 –the Joint Technical Committee of the Federation of International Geo-engineering Societies (FedIGS), gathered engineers, scientists, researchers, and educators to discuss and review IT advances in geo-engineering and provide a forum for the discussion of future trends. The conference was sponsored by the Center for Underground Transportation Infrastructure of the Colorado School of Mines and by Tongji University, China.

In accordance with the conference objective to promote advances in the development and application of IT in geoengineering, 41 full papers were presented during the six sessions of the event. The following Plenary or Keynote Lectures were delivered at the start of each session:

Hehua Zhu Tongji University, China

Kenichi Soga University of California Berkeley, USA

Youssef Hashash University of Illinois Urbana-Champaign, USA

Jian Chu Nanyang Technological University, Singapore

Chungsik Yoo

Sungkyunkwan University, South Korea

Georg H. Erharter Norwegian Geotechnical Institute, Norway

Smart Tunneling: How China is Pioneering the Future of Intelligent Construction Technology

The Value of Distributed Fiber Optic Sensing for Geotechnical Engineering

AI Transformative Potential in Geotechnical Engineering

Establishment of Singapore’s Web-Based 3D Geological Modelling and Management System Using Borehole and Geophysical Data

GIS-InSAR-AI Based Geotechnical Monitoring – Practical Applications

Digitally Empowered Geoengineering Toolbox: From AI- Driven Lab Data Interpretation, BIM Ground Modelling to Parametric Design

VIETROCK 2024

Hanoi, Vietnam

The Vietnamese National Congress of Rock Mechanics and Engineering (VIETROCK2024) was held on October 26 at the main meeting room of Power Engineering Consulting JSC 1 (member of EVN Group), located in Hanoi, Vietnam. The theme of VIETROCK2024 was “Rock Mechanics and Rock Engineering - Contemporary Issues”. In the symposium, six topics were raised:

• Offshore Energy and Reservoir Geomechanics;

• Rock Mechanics & Rock Engineering in Tunnel and underground construction;

• Rock Mechanics & Rock Engineering in Mining;

• Rock Mechanics & Rock Engineering in research Geohazard & Disaster reduction;

• Rock Mechanics & Rock Engineering in Petroleum engineering;

• Application AI and IOT in Rock Mechanics & Rock Engineering.

The symposium was held as ISRM Specialized Conference and jointly organized by Vietnam National Group of ISRMVietnamese Society for Rock Mechanics (VSRM), Institute of Geological Sciences, Vietnam Academy of Science and Technology, Drilling and Production Technology Vietnam, and PetroVietnam University.

A total of 55 abstracts were submitted and reviewed, and the proceedings contain 36 papers from 5 countries on various issues related to the field of rock mechanics and rock engineering. Prof. Ki-Bok Min, ISRM Vice President for Asia delivered a keynote lecture with the title: “The State of the Art in Anisotropic Rock Mechanics/Geomechanics”.

More than 70 participants from three countries (Korea, China and Vietnam) participated in the symposium. Several companies sponsored the event: Reinforced Earth, Geoquest (France), Rocscience (Canada), Power Engineering Investment Consulting Company Limited (PEIC Co., Ltd.), Power Engineering Consulting Joint Stock Company 1 (EVNPECC1), Vietnam Canada Transfer Technology and Research Application Co. Ltd. (VCTeck).

1ST ISRM COMMISSION CONFERENCE

ESTIMATION OF ROCK MASS STRENGTH AND DEFORMABILITY

Lima, Peru

Understanding the mechanical behaviour of rock masses is crucial in designing safe, economical, and robust engineering structures in or on rock masses. However, it has been a great challenge for the rock mechanics and rock engineering profession to predict rock mass strength and deformability in 3-D which incorporates the effect of important discontinuity geometry, relevant intact rock and discontinuity mechanical properties, and intermediate principal stress and captures the scale effects and anisotropic properties of jointed rock masses. Various procedures that belong to the following three groups have been suggested in the literature to estimate rock mass strength and deformability: based on empirical methods that use one or several rock mass classification systems, based on numerical modelling, and based on back-calculation methods using field monitored data of rock engineering structures. However, the advantages and shortcomings of the said techniques are not clear to the geo-professionals who deal with rock mechanics and rock engineering. In addition, neither standardized techniques nor accepted guidelines are available in the literature to estimate rock mass strength and deformability properties with confidence. These facts prompted the establishment of a 16-member new ISRM Commission, which represents all six continents, on the Estimation of Rock Mass Strength and Deformability in April-May 2024.

The main goal of the conference was to find out the practitioners’ and researchers’ experience with the available methods to estimate rock mass strength and deformability and their opinions. About 25 extended abstracts were received for possible presentations at the conference. Four Session Lead Lectures and 14 Regular Lectures were delivered on December 6th during 4 sessions at the conference. In addition, a 40-minute 5th session initiated critical discussions on different procedures used to estimate rock mass strength and deformability. It turned out to be a flawless, highly successful conference that received high praise from twenty-six participants who represented 7 countries.

The valuable contributions made by the authors to the conference proceedings and the opinions expressed by the conference participants during the discussions are very much appreciated. The tiring and time-consuming efforts of the local organizing committee and the conference dissemination activities performed by the international organizing committee in supporting and executing this conference are also very much appreciated.

ISRM TECHNICAL OVERSIGHT COMMITTEE 2024

REPORT

Martin Grenon | Chair, VP for North America

Milorad Jovanovski | Member, VP at Large

1. INTRODUCTION

2. CURRENT TECHNICAL COMMISSIONS

There are 22 ISRM technical commissions (Table 1) with 274 commission members from all regions. Table 1 contains a list of current commissions and the year the commission was established. Figure 1 shows the increase in commission numbers in 2024.

Kiyoshi Kishida | Member, VP at Large TABLE

The ISRM has established technical commissions to study scientific and technical matters of interest to the Society. ISRM commissions cover different topics, so they are varied in terms of their aims, type of activities, membership and products. In recognition of the critical role of the ISRM commissions for the achievement of the ISRM goals of international collaboration, advancement of rock mechanics and the promotion of high standards, the ISRM Board created the Technical Oversight Committee (here in referred to as “the TOC”), to report on the performance and to act as oversight for the commissions. The TOC assesses commission performance based on commissiongenerated Annual Reports by the chair of each commission. This report contains the TOC’s assessments of the commission for the 2023-2024 and planned activities for the next year. Full performance assessment could not be made because of the short time of activity for the Commissions.

Commissions are typically composed of 12-15 members (Figure 2). The TOC reviewed the composition of the commissions to assess and encourage diversity in participation from different national groups and regions. If analyzed by region (Figure 2), Asia and Europe participate the most in the commissions.

The number of regions represented on each commission is shown in Figure 3 and the number of members from a particular region for each commission is shown in Figure 4. The commissions on Estimation of Rock Mass Strength and Deformability (6), Deep Mining (7) and Testing Methods (21) have good representation with members from all six regions. Bio-Rock Mechanics (3) Earthquake Motions in Rock Engineering (10) have members from only 3 regions. TOC would like to request that commissions with a smaller number of participating countries ensure that members from a wide range of countries and regions can join the discussions to promote diversity.

1. ISRM TECHNICAL COMMISSIONS 2023-2024

NUMBER OF COMMISSIONS

Figure 1 - Comparison of the number of commissions for 2020, 2021, 2022, 2023 and 2024

NUMBER OF MEMBERS BY COMMISSIONS

2 - Comparison of the number of members per commission for 2024

4 - Comparison of the number of regions per commission for 2024.

COMMISSION MEMBERSHIP BY REGIONS

5 - Comparison of the number of members per commission subdivided by region for 2024.

Figure

3. SUMMARY OF COMMISSION ACTIVITIES

Previous TOCs developed a standard template for the Annual report to provide awareness of a commission’s activities, products, and progress during the year. The rating for each commission is based on the TOC’s review of the annual reports. All commissions are based on voluntary concept with the following goals:

• Encouragement of international collaboration and exchange of ideas and information among

• Rock Mechanics practitioners,

• Advancement of Rock Mechanics through Encouragement, Teaching, and Research

• Promotion of High Standards of Professional Practice among Rock Engineers

3.1.

Overview of Commission Evaluations

A full performance assessment could not be made because of the Commission's short activity time. At this stage, it can be stated that several commissions continue to perform at a very high/high level of activity high/high level of activity and that new commissions have the potential for similar levels of activity. A good number of activities, including conferences, meetings, workshops, courses, forums, and publications of relevant journal special issues and suggested methods, are planned by the Commissions for next year.

20 of the 22 Commissions produced an annual report describing the commission activities for 2023-2024. Concern with the diversity of the commissions remains. Diversity is used broadly and includes gender, ISRM region, area of study, academic-industry-national laboratories, academic heritage, etc. Membership from a single country should be ~ 30% or below the total number of members. The Number of regions should be 4 and above. TOC continues to encourage members from Africa and South America to participate in the commissions. It also continues to encourage women to participate in commissions. These metrics will be strongly considered in the evaluation process in 2025.

Publication

The Commission on Coupled Thermal-Hydro- MechanicalChemical Processes in Fractured Rock after the 3rd CouFrac conference in 2022, in Berkeley, California, high-quality extended abstracts were selected to develop full papers in several special issues based on selected paper from CouFrac 2022.

Three Special Issues were finally developed as follows.

• Rock Mechanics and Rock Engineering: Fundamental Coupled Processes in Fractured Earth Systems (https:// link.springer.com/collections/ifaaeieibh). Guest Editors Mengsu Hu, Jonny Rutqvist, Xuhia Tang.

• Tunneling and Underground Space Technology: Coupled Processes in Fractured Geological Media: Nuclear Waste Disposal (https://www.sciencedirect.com/ specialissue/1075DQ3FJC6). Guest Editors: Jonny Rutqvist, Ki-Bok Min, Pengzhi Pan.

• Journal of Rock Mechanics and Geotechnical Engineering: Computational and Numerical Modeling in Fractured Earth Systems. Guest Editors: Hideakie Yasuhara, Hyung-Mok Kim, Mengsu Hu.

In 2024, the Deep mining Commission organized a Special Issue in Underground Space. This special issue focuses on the dynamics of underground excavation, highlighting key areas that impact safety, efficiency, and sustainability in deep mining operations.

Conferences, Workshops, Short Courses

The Commission on Coupled Processes has organized a Conference, the 4th International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application (CouFrac) in 2024 in Kyoto, Japan, Nov 13-15, 2024

On Jan. 22-24, 2024, the Crustal stress and Earthquake commission organized a workshop for crustal stress and continental dynamics in Yinchuan, Ningxia Hui Autonomous Region. In this workshop, 19 oral presentations were presented.

The DDA commission organized The Second International Young Scientists Forum on Discontinuous Deformation Analysis, Online through Zoom Meeting, held on August 24th, 2024, with over 120 attendees and the International Workshops on Discontinuous Computational Methods and Rock Dynamics, with Commission on Rock Dynamics, held on March 1st, 2024 (Guanqi Chen), March 2nd, 2024 (Xiaoying Zhuang), March 15th, 2024 (Michael Gardner), and March 29th, 2024 (Luming Shen). with around 250 attendees in total.

From 2 to 5 February 2024, the ISRM Commission on Rockburst successfully hosted a focused workshop in the field of rockbursts in Beijing, the theme was "Definition of Rockburst".

3.2 Activities of the ISRM TOC

In 2024, the TOC evaluated all proposed commissions and made recommendations to the Board. The TOC assessed all reports that were received from the technical commissions and held a meeting of the TOC in India to discuss the commissions.

3.3 TOC Goals for 2025

The TOC plans to hold a meeting in 2025 with all available commission chairs to encourage their work, address questions, to facilitate collaboration among the commissions and to assess progress on video lectures and commission collaboration. A complete evaluation of the Commissions performance will also be done.

ISRM EDUCATION

FUND COMMITTEE

2024 ANNUAL REPORT

Fengshou Zhang | EFC Chair

EDUCATION FUND COMMITTEE (EFC)

The objective of the ISRM Education Fund is to further the ISRM’s mission, by enhancing education in Rock Mechanics and Rock Engineering. It will do this by planning, funding, coordinating and conducting educational activities for the benefit of the ISRM community. The ISRM Education Fund is managed by the ISRM Education Fund Committee.

ISRM Vice President, highly praised the China Society for Rock Mechanics and Engineering (CSRME) for its strong support of the ECF forum. The successful organization of this ECF session marks a new initiative for CSRME on the international stage. It not only provided a valuable platform for young scholars to showcase their work and exchange ideas but also injected strong momentum into the innovative development of the rock mechanics and engineering industry.

The members of the ISRM Education Fund Committee from 2023 to 2027 are:

9TH EARLY CAREER FORUM (ECF)

The 9th Early Career Forum was successfully held on24 September, 2024, in New Delhi, India (ARMS 13). Eight young participants delivered presentations in the forum, and they are Nahid Hasan Dipu (Bangladesh), Sai Srujan Kumar Chalavadi (India), Erdene-Ochir Jadamba (Mongolia), Muhammad Irfan bin Shahrin (Malaysia), Karthigeyan AL. Ramanathan (Malaysia), Aitolkyn Yazitova (Kazakhstan), Zarina Mukhamedyarova (Kazakhstan), and Sudip Bajgain (Nepal). Prof. Seokwon Jeon, President of ISRM, presented certificates to eight professionals.

ECF

SPECIAL EVENT

ECF special event – A Workshop on the theme of "International Young Forum on Rock Mechanics" – a EFC special event chaired by Prof. Fengshou Zhang – was successfully held in the China Rock 2024 conference, in Chengdu, 3 November 2024. Four delegates who have attended those past ECFs, two senior speakers, plus a few international young professionals from the world delivered presentations. Prof. Ki-Bok Min,

Fengshou Zhang Manchao He Ki-Bok Min Leandro Alejano

José Pavón Luís Lamas

ISRM YOUNG MEMBERS COMMITTE 2024 ANNUAL REPORT

Esteban Hormazabal, Chair

Muriel Gasc-Barbier

Jannie Maritz

INTRODUCTION

2023-2027 ISRM Young Members’ Committee established the following objectives during its initial official gatherings on February 29, 2024, in San Jose, Costa Rica:

• Attracting and engaging with young members of the society.

• Building opportunities for technical and professional learning and development.

• Showcasing and celebrating the achievements of young members.

• Providing platforms for networking and connection of young members

This report provides a summary of the committee's accomplishments during its term in line with these objectives.

In conjunction with the 2024 ISRM Symposium, committee members held their inaugural face-to-face meeting on September 22-23, 2024, in New Delhi, India to deliberate and strategize their activities for the years 2024-2025. The Young Members’ Committee is actively asking for volunteers globally and is inviting speaker candidates. If you are interested, please reach out to the committee at isrm.ym.seminar@gmail.com.

Esteban Hormazábal, Vice President for Latin America, presented a technical seminar in October 24 at the University of O'Higgins, Rancagua, Chile to explain the role of ISRM worldwide.

The seminar, chaired by Kimie Suzuki Morales, President of the Chilean Society of Rock Mechanics, lasted about four hours and was attended by more than 20 students.

YOUNG MEMBERS ORGANIZING GROUP

The ISRM Young Members’ Organizing Group is composed of 12 young members from all ISRM regions with the main duty of organizing online technical sessions which showcase the achievements of their peers. With the assistance of numerous other young society members, the committee successfully coordinated 15 webinars spanning the period from 2022 to 2024, featuring a total of 28 presentations from the following countries: Italy, France, South Korea, Japan, Peru, Chile, Netherlands, New Zealand, Norway, Australia, US, Canada, South Africa, India, Indonesia, China, Canada, Spain, United State, Italy, and Switzerland.

YOUNG MEMBERS SEMINARS SERIES

The ISRM Young Members’ Group (YMG) seminar series are virtual events, with the goal of providing a global platform for

ISRM young members to share knowledge, experiences, and ideas. The events foster knowledge and friendship among young professionals and students of rock mechanics and rock engineering on an international scale.

The series has hosted 15 live seminars, featuring more than 28 speakers from various parts of the world. The recordings of these presentations are available on ISRM Young Members YouTube channel@isrmyoungmemberschannel7287, which has been viewed over 3000 times.

The ISRM Young Members Committee and the YMG organising committee invite young members with careers in research or industry, working in the public or private sectors, to participate and share their work with the broader rock mechanics and rock engineering community.

Young members interested in this event are encouraged to contact YMG and the organizing committee through ISRM. YM.Seminar@gmail.com. Criteria for the speakers are as below:

• be an ISRM member.

• have a maximum age of 35 years, or of 40 years if a PhD degree was obtained in the previous 5 years.

• have worked in rock mechanics and rock engineering for a period no longer than 10 years.

Three seminars took places on 2024. The following conferences were delivered:

• In February with presentations on Numerical Modelling of Rock Fracture, Rock Slope Failure, Hydraulic Fracture and Earthquake Engineering by ISRM young researchers from Korea, Indonesia, Japan and China.

• In June with presentations on CO2 storage in reservoir rocks, in situ stress and induced seismicity by ISRM young researchers from Spain, Canada and USA.

• In October with presentations on probabilistic analysis in rock salt cavern, rock mechanics, numerical modelling and rock support design in hard rock tunneling by ISRM young researchers from Netherland, Spain, France and Norway.

ISRM COMMUNICATION COMMITTEE

2024 ANNUAL REPORT

Qianbing Zhang, Chair

The Communication Committee is dedicated to transforming the society’s communication strategy by creating engaging, informative, and diverse content. Inspired by the interviews published in the ISRM News Journal in July 2003, initiated under the leadership of former President Prof. Nielen Van der Merwe, we recognize the potential to further connect with our members and enrich the society’s content. He emphasized that while rock mechanics and engineering often serve profitdriven purposes, the heart of the ISRM lies in its people. The collective knowledge, collaboration, and shared experiences among members are what make the ISRM impactful.

The main objective of the Communication Committee is to enhance member engagement, promote inclusivity, and celebrate diversity within the ISRM community through innovative communication strategies. This initiative seeks to foster meaningful interactions while leveraging digital tools and active member participation to elevate ISRM’s global presence and community impact.

A series of diverse Interviews will be held to highlight the achievements, personal stories, and technical insights of ISRM members, fostering a deeper connection within the community. The interview series will feature contributions from prominent society leaders, such as ISRM Müller Award winners, ISRM

Fellows, Rocha Medal recipients and Franklin Lecturers. Face-to-face interviews will be conducted by representatives from ISRM National Groups (NG) to ensure authenticity and personalization. Allow interviews in local languages with English subtitles to reach a global audience. The commission aims to publish 6–10 interviews each year starting in 2025. Interviews will be shared across ISRM’s digital platforms, including the website and YouTube channel.

Planned Question Sets are as follows:

• Personal Questions: Explore the interviewee’s background, interests, and hobbies to connect with them on a personal level.

• Professional Questions: Delve into their career journey, key achievements, and areas of expertise in rock mechanics.

• Future Perspectives: Highlight their aspirations, thoughts on the future of rock mechanics, and advice for the next generation.

2024 REPORTS OF ISRM

VICE-PRESIDENTS

AFRICA

Jannie Maritz | Vice President for Africa

Membership from Africa seen some changes as the South African group (constituting the bulk of the African membership – typically exceeding 400 members) had cleaned up their membership database. Morrocco joined South Africa, Tunisia and Zimbabwe to be the fourth national group in Africa. With mining activities being the major focus of the southern groups, the addition of Morrocco somewhat diversifies the region. The intention is to approach several other focus groups actively involved in the field of geomechanics in the central Africa region. Accessibly due to the vast distances between operations in Africa remains a big challenge in setting up new groups. However, efforts will be directed to also include other geotechnical practitioners in the civil, tunnel and foundation studies, and those already connected though the FedIGS grouping.

Activities and initiatives of each national group within the Africa region are summarised below.

SOUTH AFRICA (SANIRE)

The society has been active in hosting several formal and social events for their members, ranging from board and council meetings to technical evenings and a national symposium. On the back of three well attended national symposia (exceeding 200 delegates), the group are setting up a larger audience symposium for 2025 resuming the AfriRock series.

A major drive has been launched towards membership numbers and member participation with activities planned for members to join and benefit from being associated to the national group of professionals.

With the bulk of the membership associated with mining activities, there are no official higher education qualification required to be a competent Rock Engineering Practitioner in South Africa, only the certificate of competence which is issued under the Minerals Council of South Africa. Even though the curriculum for this has been well established, study material is hard to come by. SANIRE together with the Minerals Council of South Africa, are investing resources into creating an online platform for members to have access to these materials while still studying towards their competency exam or have it available for quick reference when practising. Various field trips have been arranged between branch committees.

TUNISIA (TSRM)

TSRM held their 5th International Conference on Geotechnical Engineering covering topics including Four themes: Rock Mechanics, Soil Mechanics, Geomatics & Georisks and Geophysics and was well attended. Prof Ulusay presented the keynote lecture on: Geo-engineering aspects of the devastating earthquakes.

TSRM are in collaboration with NE University in China around research regarding the combined effects on High Temperature and High confining pressure on Tunisian Limestone Oil Reservoir formation.

They have also arranged for a field trip, visiting the Ain OktorKorbous-Ain Atrous Road Project (Nabeul).

The current president, Prof Hamdi, coordinated a team of professionals in assisting the ISRM board on a request to translate an English lecture presented by Prof Zhao Jian into Arabic. The final product is expected to be completed early 2025.

ZIMBABWE (ZINIRE)

Meetings are held frequently with the annual meeting held in July. They have started a young rock engineers forum with the students at the Midlands University of Mining and Geosciences, enhancing the profession between the younger generation. They also held strata control practical examination, based on the South African counterpart for assessing competence in candidates working in the mining environment.

MORROCCO (CMMSG)

CMMSG joined the ISRM with 15 members in the second quarter of 2024, sitting their first ISRM council meeting during the meeting in India. The hosted their national conference during October 2024 and was well attended with over 300 delegates, 20 stands and 4 keynote lecturers. During the conference, the ISRM Board had an opportunity to introduce ourselves to the newly formed group. Prof Muriel GascBarbier, Vice President Europe, represented the society, giving a keynote as well as session around the ISRM.

ASIA

Ki-Bok Min | Vice President for Africa

As of 2024, ISRM activities in Asia demonstrate significant progress, active participation, and remarkable membership growth over the past decade. This report outlines key developments, membership trends, and notable initiatives undertaken by the region’s national groups (NGs).

MEMBERSHIP GROWTH AND NATIONAL GROUP DEVELOPMENT

Membership in Asia has reached an all-time high of 3,808, marking an impressive 82% increase since 2014. The number of national groups has expanded from 12 in 2014 to 15 in 2024. Efforts to reinstate inactive groups, such as Iran, have been successful, and discussions are ongoing to establish additional NGs in new countries.

The ISRM Asian Council Meeting was held during ARMS13 in India, with representatives from across the region.

HIGHLIGHTS OF NATIONAL GROUP ACTIVITIES

CHINA

The Chinese Society for Rock Mechanics and Engineering (CSRME) continues to lead in Asia and globally, representing 2,762 members, over 70% of the region’s total. CSRME leads 10 of ISRM’s 22 commissions, hosts major events like the GeoShanghai International Conference (700 attendees) and the Sino-Russian Forum on Deep Rock Mechanics, and publishes a variety of international journals. The flagship event, CHINA ROCK 2024, was held on November 1–4 in Chengdu, featuring a remarkable 126,432 online and offline participants. Its innovative three-tier model included one main venue, 15 central hubs, and 277 satellite venues at universities and companies. The conference featured 13 keynote speakers, including Profs. Ki-Bok Min and Milorad Jovanovski, with hybrid online/offline presentations and simultaneous English-Chinese captions.

JAPAN

The Japanese Society for Rock Mechanics (JSRM) continues to excel academically and professionally, supporting 291 ISRM members. JSRM offers up to four scholarships annually for young professionals to attend international conferences and recognizes outstanding theses and research. The group hosted the Japan-Korea Joint Symposium, the 50th Japan Rock Mechanics Symposium, and ISRM Specialized Conference CouFrac2024 (November 13–15) with 269 participants. Notable achievements include two award recipients: Dr. Kazuki Sawayama (Rocha Medal) and Dr. Weiren Lin (ISRM Science Achievement Award). Japan will host 14th Asian Rock Mechanics Symposium on 22-26 Nov 2026 in Fukuoka.as an ISRM International Symposium.

ISRM Asian Council Meeting was held during ARMS13 in India with representatives from Asian Countries.

ChinaRock2024 in Chendu with 15 central venues and 277 satellite venues held hybrid online/offline format.

INDIA

The ISRM National Group India has 199 members and has been instrumental in addressing infrastructure challenges. Key events include the National Workshop on Slope Stabilization and the Conference on Drilling and Blasting for Tunneling Projects. India successfully hosted ARMS13 in Delhi (September 21–27) with approximately 300 participants. The biannual ISRM (India) Journal remains a cornerstone for research dissemination.

KOREA

The Korean Society for Rock Mechanics and Rock Engineering (KSRM) has 172 members and 10 corporate affiliates. KSRM organizes two annual conferences, produces six newsletters, and collaborates internationally on nuclear waste disposal initiatives. Preparations are underway for the 2027 ISRM Congress, aiming to make it the "Rock Mechanics Olympics" with record-breaking attendance.

SINGAPORE

The Society for Rock Mechanics and Engineering Geology (SRMEG) actively engages its 132 members through monthly seminars, a short course on Singapore’s geology, and collaborations with Malaysia. SRMEG also contributed to the Sino-Singapore Underground Space Alliance and co-hosted the 18th ACUUS World Conference on Urban Underground Space.

INDONESIA

The Indonesian Rock Mechanics Society (IRMS) with its 56 members focuses on education and industrial collaboration through workshops and symposia, including the 1st National Symposium of Engineering Geology. It also supported the International Conference on Tunneling and Underground Space for Sustainable Development.

SOUTHEAST ASIA

Southeast Asia national group represents 14 members, mainly from Chinese Taipei. Chinese Taipei hosted its annual Rock Mechanics Conference at National Yang Ming Chiao Tung University, attracting around 200 participants.

BANGLADESH

As a new NG since 2023, the Bangladesh Society for Rock Mechanics focuses on developing local expertise with its 13 members, particularly in addressing shale slope failures. Their commitment to promoting sustainable practices is commendable.

IRAN

Iran has been Reinstated as an ISRM NG in 2024, Iran represents 11 members and has a historically strong presence in rock mechanics. Its return has been warmly welcomed.

ISRAEL

The Israel Rock Mechanics Association (IRMA) engages its 15 members primarily in teaching activities. Courses cover rock mechanics and engineering and are part of the geotechnical engineering curriculum at Ben Gurion University.

MALAYSIA

Malaysia’s 46 members are affiliated through Society for Engineering Geology and rock mechanics Malaysia (president Rasid Jaapar). Malaysian members took part in 14th Asian Regional Conference IAEG and work closely with neighboring Singaporian Group.

ChinaRock2024 closing ceremony.

Kick off meeting of Organizing Committee for ISRM Congress 2027 in Seoul

MONGOLIA

The Mongolian NG released its inaugural newsletter in 2024 and hosted workshops introducing ISRM and IAEG activities. It actively engages its 30 members through online annual meetings.

CONCLUDING REMARKS

As ISRM VP for Asia, I had the honor to be able to travel around the world and witnessed the vibrant rock mechanics activities. Followings are the events that I attended in my capacity as ISRM VP for Asia during 2024.

NEPAL

The Nepal Society for Rock Mechanics has 11 members and collaborates with tunneling and hydropower industries. Key events in 2024 include the Nepal Tunneling Conference and the Evert Hoek Memorial Day, honoring contributions to the field.

SRI LANKA

The Sri Lankan Rock Mechanics and Engineering Society (SLRMES) actively engages its 38 members through webinars, technical tours, and its inaugural international conference. It also leads an ISRM commission on rock mass strength and deformability.

VIETNAM

Vientnam currently has 11 members through Vietnamese Society for Rock Mehcanics (VSRM, President Do Nhu Trang). VSRM hosted VIETROCK2024 on 26 Oct 2024 which was ISRM specialized Conference.

- Japan-Korea Joint Symposium on Rock Engineering 2023, 10-11 Jan, 2024, Tokyo, Japan

- 58th US Rock Mechanics/Geomechanics Symposium, 23-26 June, 2024, Golden, Colorado, USA

- ISRM European Rock Mechanics Symposium (EUROCK2024), 15-19 July, 2024, Alicante, Spain

- 4th Shortterm Prediction of Rock Failure Competition (STPRFC) hosted by ISRM Commission on Ultradeep Rock Mass Mechanics and Engineering, 9-12 Aug, 2024, Taiyuan University of Technology, Taiyuan, CHINA

- 13th Asian Rock Mechanics Symposium (ARMS13), 21-27 September, 2024, New Delhi, India

- Vietnamese International Congress for Rock Mechanics and Rock Engineering (VIETROCK2024) – ISRM Specialized Conference, 26 Oct, 2024, Hanoi, Vietnam

- 21th Annual Conference of China Rock Mechanics and Engineering (China Rock 2024), 1-4 Nov, 2024, Chengdu and online, China

Asia remains central to ISRM’s global activities. The steady growth of NGs and membership reflects the commitment of national groups and the broader rock mechanics community. Greater support for emerging regions will be critical to sustaining this momentum and achieving ISRM’s vision for global inclusivity and impact.

Evert Hoek Memorial Day organized by Nepal Society for Rock Mechanics (NSRM)

AUSTRALASIA

Qianbing Zhang | Vice-President for Australasia

INTRODUCTION

The two national groups for Australasia are:

• Australian Geomechanics Society (AGS)

- 534 individual members (an increase from 492 in 2023, 15.7% growth)

- Chair: Tim Thompson (2024-2025)

- Secretary: Jon Gibbs

• New Zealand Geotechnical Society (NZGS)

- 235 individual members

- Chair: Philip Robins

- ISRM Liaison: Eleni Gkeli

AGS and NZGS are technical societies of National Engineering Institutions:

• Engineers Australia

• Engineering New Zealand

These societies are National Groups for:

• International Society for Rock Mechanics and Rock Engineering

• International Society for Soil Mechanics Geotechnical Engineering

• International Association for Engineering Geology and Environment

General activities of the two societies include:

• Local chapter/branch meetings

• Monthly technical seminars by Professionals

• Student focused events

• Distinguished Speakers Series (coordinated by both NZGS and AGS national committees for arranging the tours; i.e. UK Rankine Lecture winners)

• Annual Chapters and National symposiums

• Workshops and courses (Engineering geology, Geotechnical mapping, Core logging)

• Coordination of national standard reviews

KEY ACTIVITIES FOR 2024

The major event of the year for the region is the 15th Young Geotechnical Professionals Conference, taking place from 6–9 November 2024 in Adelaide, Australia. This conference, a joint initiative by AGS and NZGS, is held biennially for geotechnical professionals from Australia and New Zealand under the age of 35. Two awards are presented: the Don Douglas Youth Fellowship Award, which includes a $4,000 prize for the most outstanding paper, and the NZGS Young Geotechnical Professionals Fellowship, awarded for the best paper.

The 47th ISRM Online Lecture was delivered by Prof. Ranjith Pathegama Gamage from Monash University. The lecture title is: “Deep Geothermal Energy: A Key Player in the Sustainable Energy Mix”.

Additionally, both AGS and NZGS local chapters have organised several events throughout 2024. These include technical talks held either in person or as online webinars, annual symposia, and workshops. Selected events from both societies are listed below.

SELECTED AGS ACTIVITIES

The AGS operates across seven chapters, for example, Victoria Chapter hosts a diverse set of events. The Annual Symposium on 18 September 2024. Alongside this, the Victoria Chapter is also organizing field trips, short courses, and technical events aimed at enhancing geomechanics knowledge and fostering professional networking within the community. These activities provide valuable opportunities for continued learning and collaboration.

AUSTRALIAN GEOMECHANICS SOCIETY (AGS)

SELECTED NZGS ACTIVITIES

The NZGS operates 10 branches across New Zealand, actively engaging geotechnical professionals. For example, the Christchurch branch has 34 members and will be hosting the YGP Symposium on 3 October 2024. NZGS supports three main focus groups: core knowledge, young geo-professionals, and sustainability and climate change. Through these initiatives, NZGS is dedicated to advancing geotechnical knowledge and addressing critical sustainability challenges.

AGS AND NZGS PUBLICATIONS

Both AGS and NZGS are integral in providing valuable technical resources and fostering industry knowledge. AGS shares educational and technical videos, while NZGS contributes through guidelines and symposium proceedings. These efforts are critical in advancing research and enhancing the skills of professionals in the rock mechanics community.

The Australian Geomechanics Journal, published quarterly, is a key resource from AGS. For example, in the Volume 59, VP’ highlights include the key activities from ISRM Board Meeting,

• Australian Geomehanics Journal — quarterly (highlights by ISRM VP)

• New Zealand Geomechanics News — twice a year (Report by ISRM VP)

with a focus on expanding ISRM diversity, increasing visibility in Australasia, and boosting participation in ISRM initiatives. New Zealand Geomechanics News is published twice a year. In the latest News, the Report by ISRM Liaison, covers most rock mechanics activates. The journal continues to provide key insights into geotechnical engineering, particularly with the focus on recovery efforts and new ISRM methodologies aimed at improving practices globally.

CONTRIBUTIONS TO THE ISRM COMMISSIONS

Members from Australasia contribute significantly to ISRM Commissions, with several members leading initiatives:

Leading Commissions

• Beyond Limits: Rocks in the Face of Extreme Conditions, chaired by Wasantha Liyanage (Australia)

• Planetary Rock Mechanics, chaired by Serkan Saydam (Australia)

• Rock Weathering and Erosion, co-chaired by Zhongwei Chen (Australia) and Prof. Yanli Huang (China)

Participation in Commissions

• Artificial Intelligence in Rock Mechanics and Rock Engineering, Joung Oh (Australia)

• Crustal Stress and Earthquake, Mojtaba Rajabi (Australia)

• Deep Mining, Murat Karakus, Ranjith Pathegama Gamage, and Sevda Dehkhoda (Australia)

• Design Methodology, Mostafa Sharifzadeh (Australia)

• Discontinuous Deformation Analysis – DDA, Shan-Yong Wang (Australia)

• Earthquake Motions in Rock Engineering (EMIRE), Selahattin Akdag (Australia)

• Estimation of Rock Mass Strength and Deformability, Hossein Masoumi (Australia)

• Risks and Reliability in Rock Slope Engineering, Phil de Graaf (Australia)

• Rock Dynamics, Jian Zhao (Australia)

• Rockburst, Murat Karakus and Ismet Canbulat (Australia)

• Soft Rocks, Mostafa Sharifzadeh (Australia)

• Testing Methods, Sevda Dehkhoda (Australia)

• Ultradeep Rock Mass Mechanics and Engineering, Pathegama Gamage Ranjith (Australia)

EUROPE

Muriel Gasc-Barbier | Vice President for Europe

NUMBERS

Europe is the ISRM region with the largest number of National Groups (NGs) with 30 countries represented. That corresponds to half the countries represented in ISRM and around 1/3 of ISRM members (around 3100). 30 countries imply nearly 25 languages and as many ways of doing things. Depending on the countries, NG can be on their own or associated with other local FedIGS associations (mostly engineering geology and soil mechanics), but also tunneling or mining societies.

CONFERENCES IN EUROPE IN 2024

The Spanish NG successfully organized the Eurock 2024 symposium in Alicante in July 2024. Around 300 papers were accepted and around 300 delegates from 39 countries attended the symposium. 3 very interesting short courses were given the day before the symposium: “Microstructural characterization of rocks”, “Mapping rock mass discontinuities from 3D point clouds” and “Practical use of structural geology in rock tunnels”. During the symposium we had the opportunity to listen to five excellent keynote lectures delivered by Eduardo Alonso, Michel Jaboyadoff, José Muralha, Andrea Sagalini and Philippe Vaskou. An excellent representation of the industry was to be seen in the technical exhibition, with more than 10 companies. A guided tour of the old city was proposed as well as two very nice excursions after the congress. It was all very successful.

EUROCK 2024

July 2024 was quite busy as the 14th International Symposium on Landslides (ISL2024) held by JTC1 which took place in Chambery (France) just before Eurock. Around 380 attendees from 45 countries enjoyed the keynotes, scientific and poster sessions as well as one or more of the 5 excursions organized in the middle of the symposium. 13 students from 7 countries attended the pre-symposium 2-day summer school dedicated to landslides and rockslides from hazard to mitigation.

CONFERENCES IN EUROPE IN THE FOLLOWING YEARS

Trondheim in Norway was chosen to hold Eurock 2025, after cancellation of Eurock 2020 due to Covid pandemics. It was during the Council meeting hold in Salzburg in 2023, that Trondhein was selected to become the venue of the international ISRM symposium in 2025. The organization of this event is going well: around 300 abstracts were submitted before the deadline and the program sounds very promising with 7 keynote speakers, a pre-congress tour and 3 technical tours. Workshop/short courses will be announced soon. A rock-bowl challenge as well as an Early-Career Forum are also planned during the symposium. Registration will open on January and we hope to see many ISRM members there, for the council meeting as well as the symposium. We wish our Norwegian colleagues all the best for these final months of preparation.

Sköpje in North Macedonia has been chosen as the venue of Eurock2026 in September 2026 under the chosen theme “risk management in rock engineering”. The organizing committee is deeply involved to make it a big event. 3 workshops and invited well-known keynotes lecturers are already under consideration. We also wish our Macedonian colleagues all the best for the preparation of this congress.

INFORMAL EUROPEAN COUNCIL MEETINGS

Following former organization, the ISRM VP for Europe organize annually informal council meetings of the European NGs. The last but one European council informal meeting took place in October 2023, during the ISRM International Congress in Salzburg. It was an opportunity to make the transition between the former VP Europe, Leandro R. Alejano, and the new elected one, Muriel Gasc-Barbier who warmly thanked her predecessor for the work he had accomplished.

Another Informal council meeting was organized in Alicante during Eurock2024. It was the occasion to present the new elected board, its missions and objectives. 12 attendees from 10 countries were also able to discuss the latest news. The minutes of the meeting was sent to all NG representatives in early September 2024.

ISRM EUROPEAN ROCK MECHANICS DEBATES

Based on an initiative of Charlie Li, Leandro Alejano, and with the agreement of the Europe council, European Rock Mechanics Debates in Zoom have been organized by the ISRM VP for Europe with the help of Philippe Vaskou from France since October 2021. The second one took place in June 2022, the 3rd in January 2023 and the 4th in June 2023.

The fifth European debate took place on April 8th 2024 and it addressed the following topic: “Rock bolting: approaches in mines and for tunneling”, starring Charlie Li (Norwegian University of Science and Technology – Norway) and Robert Galler (GEOCONSULT Consulting Engineers - Germany).

The debate was hold on the Zoom platform and broadcasted through the ISRM YouTube channel, where it can be revisited just as all the previous ones. At date it had been viewed nearly 1000 times.

The sixth debate was organized on October 16th 2024. It focused on “failure criteria: Mohr-Coulomb versus Hoek & Brown” and the speakers were Joseph Labuz (University of Minnesota - USA) and Ming Cai (Laurentian UniversityCanada). We add so many registrations that we had to upgrade our zoom license to let more than 100 people to attend. On the day, we were up to 138 connected at the same time and in a month and a half, it was viewed more than 400 times.

It is important to warmly thank Philippe Vaskou, who organized all the debates, contacted the speakers and acted as moderator. The debates would not have been possible without his tireless efforts.

MISCELLANEOUS ACTIVITIES OF THE NGs

As mentioned at the beginning of this report, the activities developed by European ISRM NGs are varied. The 2-3 most relevant activities of European NGs are synthetized in the following table, based on the answers of ISRM NG’s presidents to a call sent by the ISRM VP. In addition to that, a good number of other activities including rock mechanics days, working group studies, awards for young researchers, professional or academic short courses, excursions to relevant sites or projects and so on take place in the different countries of Europe fostered by the National groups. Some pictures are also added.

ACTIVITIES

AUSTRIA

BELGIUM

BULGARIA

• 73th Geomechanics Colloquium 2024 was organized with 807 participants + 241 exhibition staff + 277 pupils, 70 exhibitors, 2 excursions, a concert and the Gala evening at Stieglkeller

• Research funding: 80,000.-€ (until End of October)

• 10/11/2023: Visit to the Brussels metro worksite - Constitution station

• 19/2/2024: Hydrogen storage in underground environments (technical day)

• 17/5/2024: Need and access to resources in a context of energy transition" (Workshop organized with SIM.

• XI International Geomechanics Conference, 16–20 September 2024 at the Astera Hotel & SPA, Golden Sands Resort, Bulgaria.

• IX National Scientific and Technical Conference with International Participation “Technologies and Practices in Underground Mining and Mine Construction”, 7 - 10 October 2024 in SPA complex Orpheus, Devin, Bulgaria.

CROATIA

CZECH REPUBLIC

• 9th conference of the Croatian Geotechnical Society with international participation and under the auspices of ISSMGE was held 04 to 06 May 2023 in Sisak, Croatia. https://www.hgd-cgs.hr/savjetovanja/ sisak-2023/?lang=en

• CGS and MAG will organize the 9th International Conference on Earthquake Geotechnical Engineering (9ICEGE) in 2028.

• 2 CGS Bulletin’s published last year.

• 2024.06.13.-15. Seminar "Geotechnical constructions" as a part of 18th days of Croatian Chamber of Civil Engineers in Opatija, Croatia. https://dani.hkig.hr/HKIG_OPATIJA_2024_PROGRAM.pdf

• 2024.05.06. Organized visit for members to reconstruction sites in the greater Petrinja area, the sinkholes, and travel through the beautiful hills of Banovina. https://www.hgd-cgs.hr/savjetovanja/ sisak-2023/strucna-ekskurzija-u-subotu-6-svibnja/?lang=en

• International conference - New Knowledge and Measurements in Seismology, Engineering Geophysics and Geotechnical Engineering, April 9-10, 2024

• Co-organizing of the Workshop on Recovery of Mining District Network (COST action CA22138), January 22-23, 2024

• Participation on Program of the Czech Academy of Sciences – Dynamic planet Earth in the frame the Strategy AV21

FINLAND

• Finnish Rock Mechanics Day 27.09.2023

• Training on near surface rock mass stress state measurements

• Annual meeting

• Various young members’ excursions, events and award

FRANCE

GREECE

ICELAND

ITALY

NORTH MACEDONIA

• 4 technical sessions: Avril 2024 Geomechanical challenges in industrial CO2 and H2 storage in geological formation organized with SPE France and EAGE Paris Chapter; May 2024 Underground fluid injection and consequences CFMR-Jeunes; October 2024: poromecanique and rock physics; December 2024: and

• General Assembly with Jean Mandel Lecture given by Antonio Gens (UPC)

• Organising committee of JNGG 2024 (www. jngg2024.sciencesconf.org) and ISL 2024 (www. isl2024.com)

• Organization of the 9th Hellenic Conference on Geotechnical Engineering – Athens, Greece / 4 – 6 October, 2023.

• 14th Athenian Lecture on Geotechnical Engineering was given by Dr Paul Mayne, Emeritus Professor of Georgia Institute of Technology, Atlanta, USA.

• The 3rd Blight Lecture by Professor Eduardo Alonso was given during the 8th Int. Conf. on Unsaturated Soils held on Milos Island, Greece, in April

• Field excursion of the Icelandic Geotechnical Society, including the ISRM National Group, to the hazard zones of recent extreme tectonic and volcanic activity in SW-Iceland, on May 23rd, 2024.

• 3 meetings on general geotechnical topics, including rock mechanics and rock engineering as the Icelandic RM society is merged with Icelandic ISSMGE and IAEG

https://en.vedur.is/about-imo/news/volcanic-unrest-grindavik

• 2nd International Workshop on Complex Formations - Torino (Italy) - 9th May 2023

• ISRM Young Members’ Seminar series – 7 September 2023 - Webinar: Block volume and shape and their role in rockfall problems - Dr . Battista Taboni (Polytechnic of Turin, Italy

• Annual assembly of MAG. Invited lecture by prof. Resat Ulusay from Turkiye on subject: “Main geotechnical characteristics of the 6 February 2023 Kahramanmaraş doublet earthquakes of Türkiye and lessons learned”

• 25-29.6.2024. MAG Organized and hosted the 28th European Young Geotechnical Engineers Conference EYGEC 2024. Over 40 PhD participants from Europe and wider attended the conference

• Participation of several MAG members to international conferences (14th Austrian Geotechnical Conference, 3rd ISSMGE ESA, 8th ICEGE, Osaka, Japan, Regional Symposium on Landslides in the Adriatic-Balkan region, Belgrade, Serbia, EUROCK 2024, 4th ISSMGE, …

PORTUGAL

THE NETHERLANDS

• 23 August 2024: 12th Porrtuguese-Brazilian Geotechnical Congress and 8th Portuguese-Spanish Geotechnical Seminar

• 25 November 2024: XLI Manuel Rocha Lecture by Prof. António Viana da Fonseca, entitled Metastability of soils and fragility of earth works

• 15 January 2024 - Visit of IAEG President Vassilis Marinos at TU Delft - Kick off of the IAEG2026 congress preparation

• 05 April 2024 - General Assembly & Ingeokring Get together! event at Royal Haskoning-DHV, Amersfoort. Series of lectures on Assessment of existing dam structures

• 24 August 2024 – Excursion to Limburg, NL– Post-mining risk management in Valkenburg Calcarenite mines

• October 2024- IAEG2026 congress organizing team in Dubrovnik for EuroEngeo2024.

• 22 November 2024: Ingeokring Symposium- Double celebration: 50th anniversary of IngeoKring and 60th anniversary of IAEG - Announcement of Ingeokring Best MSc thesis award winner

NORWAY

• January 2024: Course: Rock technology for TBM drilling in hard rock

• March 2024: Seminar: Spring release 2024 - Lifetime on rock protection

• March 2024: Annual meeting for members only

• November 2024: Conference: Rockblasting Conference

• Various Board meeting for EUROCK 2025 organization

• various grants were supported for students to travel in technical geosciences studies as well as the work with FRSDB (Fennoscandian Rock Stress Data Base) and ROCARC (Rock anchoring for stabilization of infrastructures.

SPAIN

SWEDEN

• Two SEMR Annual meeting (27-04-2023: Rock mechanics of underground projects. In person meeting with more than 100 attendants - 23-05-2024: BIM methodology on Rock Engineering In person meeting with more than 90 attendants)

• X Biennial award for young researchers

• Organizations of the Eurock 2024 held in Alicante

• An independent association for the Swedish NG has been established in April 2023. The members have approved statutes on the First annual meeting in May 2023, that clearly state what the association must work towards: The board of the NG of Sweden decided to form a "Swedish engineering geology" committee for the association. The committee shall make visible and develop engineering geology in the country. Development of method descriptions for engineering geological investigation of various kinds shall constitute a key activity for the committee. This must be designed and made available so that it will benefit the rock construction industry.

• A logo has been developed for the Swedish national group

• National Rock Mechanics Day in March 2024 with a guest lecturer Geoff Beale, Piteau Associates, UK who gave a talk about “Dealing with water in rock mechanics applications”

SWITZERLAND

• Spring Conference in Yverdon-les-Bains “Numerik in der Geotechnik” (Numerical Modelling in Geotechnics)

• Fall Conference in Olten “Nachhaltigkeit in der Geotechnik» (Sustainability in Geotechnical Engineering)

• Annual Meeting 21th March 2024 in Luzern

• Activities for young people: 3rd Design Challenge in Spring, 30th August 2024 site visit railway station Bern, 23rd October 2024 Fall event with two speakers “Quantified climate reporting in geotechnical engineering & sustainable analytics”

TURKEY • Participation at IMCET 2023 (28th International Mining Congress and Exhibition Türkiye)

• UYAK 2023, 5th International Underground Excavations Symposium and Exhibition was held in Istanbul, Türkiye on June 5-7, 2023. The symposium was organized by the UCTEA Chamber of Mining Engineers and supported by the Turkish National Group of ISRM. The president attended the symposium as a session chair and the vice-chairperson presented a technical paper in the symposium.

UNITED KINGDOM

• The British Geotechnical Association (BGA) Annual General Meeting and Annual Conference took place on 12th June 2024. The focus was rock mechanics, to celebrate the launch of the geotechnical version of FracMan. With the focus being rock mechanics, it was organized by Dr Tasos Stavrou (WSP) and James Lawrence

• The 62nd Rankine Lecture was given on the 13th March 2024 by Professor Lidija Zdravković of Imperial College London on “Geotechnical Engineering for a Sustainable Society”.

• The British Geotechnical Association held its 75th Anniversary Conference and Dinner at the Institution of Civil Engineers on 15th October 2024.

NORTH AMERICA

Martin Grenon | Vice President for North America

Membership: The total ISRM membership in North America is approximately 566 members. The US National Group, ARMA, has 421 members, and the Canadian National Group, CARMA, has 145 members.

UNITED STATES OF AMERICA

The American Rock Mechanics Association, ARMA, http:// armarocks.org/ represents the ISRM’s National Group for the United States of America and currently has 739 members. The President of ARMA is Professor Andrew Bunger, University of Pittsburgh.

The ARMA 58th US Rock Mechanics/Geomechanics Symposium took place in June 2024 in Golden, Colorado. Over 640 papers were presented during 41 technical sessions, and 794 participants were from 35 countries. Four keynote speakers were present. The symposium was preceded by three workshops, two short courses, and three technical tours.

Plans are underway to organize the 59th ARMA Symposium, scheduled for June 8-11, 2025, in Santa Fe, NM. The technical program will focus on theoretical advances and innovative applied research in rock mechanics and geomechanics. Technical tours and field trips are planned. Short courses and workshops will be held before the symposium.

ARMA has a growing number of student chapters supporting engagement with the next generation of practitioners. There are three new student chapters since the Atlanta Meeting — 28 approved to date and growing each year.

ARMA HONOURS AND AWARDS

Paul Young, Professor Emeritus, University of Toronto, was inducted as a 2024 ARMA Fellow. The ARMA Fellows program recognizes individuals who have achieved outstanding accomplishments in rock mechanics and contributed to the professional community through ARMA. The total number of current members increases to 30. ARMA Presidential citations went to Herbert F. Wang, Professor Emeritus, University of Wisconsin-Madison.

The NGW Cook Ph.D. Dissertation Award was given to Sana Zafar (Colorado School of Mines) for Geophysical Signatures of Crack Initiation and Growth in Rocks under Uniaxial Compression. The Case History Award was presented to Neda Dadashzadeh, Lindsay Moreau-Vertaan, Kathy Kalenchuk: Methodology for Quantifying Domain-Based Seismic Hazard Using Robust Causal Factor Analyses Focused on Geology, Geometry, and Mining Activities. The Distinguished Service Award was presented to Wei Fu (junior level) and Akash Chaurasia (student level). The Applied Rock Mechanics Award was presented to Andrea Lisjak, Omid Mahabadi, and Bryan Tatone (Geomechanica, Inc.): Acceleration of a 2D/3D Finite-Discrete Element Code for Geomechanical Simulations Using General Purpose GPU Computing. The Class of 2024 new Future Leaders inducted were Aly Abdelaziz, Kai Liu, Yongzan Liu, Taghi Sherizadeh, Pabasara Wanniarachchige and Isabella West.

The seven active ARMA technical committees are discrete fracture networks, hydraulic fracturing, induced seismicity, drilling mechanics and engineering, underground storage and utilization, tunnelling, and artificial intelligence and data. These groups have a “community of common interest” and are run by ARMA member volunteers. Interested individuals can join the communities organized under each technical area. Each area sets its agenda and conducts a variety of activities. Some produce technical–related publications, and others conduct virtual seminars and education sessions.

CANADA

The Canadian Rock Mechanics Association (CARMA - http:// www.carma-rocks.ca/fr/accueil/) represents the ISRM’s National Group for Canada. Members are from CARMA’s two constituent groups, the Rock Mechanics Division of the Canadian Geotechnical Society (CGS) and the Society for Rock Engineering of the Canadian Institute of Mining and Metallurgy (CIM). CARMA currently has 145 active members.

The President of CARMA is Dr. Kamran Esmaeili, Professor University of Toronto, who is also the chair of CIM-RES. During 2023-24 CARMA has done the following activities:

Three webinars were jointly organized by CIM-RES and CGS:

• Dr. Matthew Pierce, Application of Systematic Point Load Testing to Characterization of Massive, Veined Orebodies, September, 2023

• Dr. Marco Quirion, The role of rock engineering in hydroelectric schemes from design to operation, March 2024

• Dr. Patrick Andrieux, The Destressability Index for the Design of Large-scale Confined Destress Blasts, June 2024

• A PhD thesis award was created after Prof. Dough Stead, and two awards have been presented to top PhD theses in rock mechanics and rock engineering. The award-winning students were financially supported to attend Canadian conferences.

• A MSc thesis award was created after Prof. Evert Hoek, and one master's thesis was selected to receive the award during the Geo-Montreal conference.

• CARMA is supporting the organization of the conference ROCKENG 2025, which will be held in August 2025.

The CIM-RES

• Dr. Kamran Esmaeili, Professor University of Toronto is the chair of CIM-RES.

• CIM-RES currently has 302 active members, and 17 are members of CARMA.

• CIM’s Rock Mechanics Awards were presented to Dr. Erik Eberhardt in 2023 and to Dr. Veronique Falmagne in 2024.

• CIM-RES has selected top papers presented during the CIM annual conferences in 2023 and 2024 for a special issue of CIM journal, which is expected to be published in Q1-2025.

• CIM-RES has presented two awards of $750 each to best students’ posters during the CIM annual conferences in 2023 and 2024.

The CGS-RMD

• Dr. Jonathan Aubertin, Professor at École de Technologie Supérieure and Dr. Jennifer Day, Professor at Queen’s are co-Chair of CGS-RMD.

• The CGS RMD https://www.cgs.ca/division_rock_ mechanics.php has currently 95 1st choice and 238 2nd choice members. One hundred twenty-eight (128) are members of CARMA.

• Several Rock Mechanics sessions took place during the GeoSaskatoon 2023 conference.

• Joe Carvalho was awarded the 2023 John Franklin Award at GeoSaskatoon 2023.

• Amir Javaid was awarded the inaugural best rock mechanics paper at GeoSaskatoon 2023. This new recognition will be awarded annually at the CGS national conference.

LATIN-AMERICA

Esteban Hormazabal | Vice President for Latin-America

The ISRM Latin American region has nine National Groups: Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Mexico, Paraguay and Peru. The region has a number of associates of more than 435 members. The participation of academics, practitioners, and students in rock mechanics was relevant. The interaction between societies has been successful during the year. In addition, representatives of the societies have participated in regular regional meetings to discuss main activities and plan for the future.

Seminars, courses, and webinars have reached many professionals, and a growing demand for training in different areas. Open pit mines and Tunneling stood out with special mention.

The Geotechnical Society of Costa Rica hosted the "International Workshop on Recent Advances in Rock Mechanics" in San José, on 1 March, in conjunction with the ISRM Board meeting. This was the first ISRM activity organized in a Central American country. A rich program with presentations by all Board members and several experts from

Costa Rica and a fruitful discussion of technical issues on topics of interest took place.

This first meeting of the 2023-2027 ISRM Board, which took place on 29 February and 2 March, had the main objective of defining and starting the implementation of new initiatives for its 4-year term of office.

Some important activities of the National Group are mentioned below:

ARGENTINA Online presentations and Webinars. http://saig.org.ar/congresos/ BOLIVIA

Online presentations and Webinars. https://www. geomecanicabolivia.com BRAZIL

International Slope Stability Conference, Belo Horizonte April 2024 and X Brazilian Rock Mechanics Seminar in Cambioru, September, 2024. YouTube videos about laboratory tests and Online presentations published on seminars. Journals published quarterly and social media.https://www.cbmr.com.br.

CHILE

Seminars and Webinars like “Geotechnical risks”, Viña del Mar, June 2024 and Role of the support system in the rockburts risk control, Rancagua, October 2024. https://www.scmr.cl. COLOMBIA

Online presentations and Webinars. https://www.scg.org.co

COSTA RICA

XIV National Congress of Geotechnics, San Jose, March 2024. https://www.geotecniacr.com

MEXICO

7th International online Seminar of Tunels and Shafts in Soils and Rocks, Mexico City, May, 2024 and XXXII National Meeting of Geotechnical Engineering, Mexico City, September 2024. Journals published twice a year and social media. http://www.smig.org.mx

PARAGUAY

Online presentations and Webinars. https://larms2022.com/ PERU

VIII Geoengineering Peruvian Symposium, Lima, December 2024 and the first ISRM Commission Conference on Estimation of Rock Mass Strength and Deformability, Lima, December 2024 http://speg.org.pe.

In each term of office, the ISRM Statutes allow the Board to appoint a maximum of three VicePresidents at Large. Their role is to support their regional Vice-President and to contribute to the Board activities, to ISRM Committees and Commissions and sponsored events, and to assist the organizing commission of the sponsored events with their know-how.

MILORAD JOVANOVSKI

This is the outline of the activities of Milorad Jovanovski as VP of ISRM at Large during the period from October 2023, when he was elected in this position during the ISRM Congress in Saltzburg, Austria, till the end of 2024. The activities can be divided into several main part as:

• Activities for promotion of ISRM and contacts with countries that are intending to form new NG in ISRM

• Activities at a National level related to Rock Mechanics or Geotechnics

• Activities ads invited or keynote lecturer

• Activities at ISRM Conferences or Symposiums

the 21th Annual Conference of the Chinese Society for Rock Mechanics, China Rock 2024

• Activities in a frame of ISRM Board and Council Activities for promotion of ISRM were related with intensive contacts with ISRM community and the preparation of first edition of ISRM pins. The pin design was chosen together with ISRM President and Board members, and they were a gift from Macedonian Association for Geotechnics (MAG) to ISRM. They have been distributed to the ISRM members on ISRM events as Board meetings in Costa Rica, Spain (Eurock 2024) and in India (ARMS13).

During this period, together with Board members Ki-Bok Min and Esteban Hormazábal, we had intense contacts with representatives from Kazakhstan, Iraq, Montenegro, Romania, Poland and other countries, with the goal to establish new NG or reestablish some former NG which are not active at the moment.

Besides an introductory speech as ISRM representative on a webinar: Second Generation of Eurocode 7 - Rock engineering, organised by ISRM, ISSMGE and Royal Netherland Standardization Institute (NEN), Milorad Jovanovski delivered several invited lectures as listed below:

• Methodology for landslide risk assessment – case study of Poroj River catchment area: on-line presentation on the Fourth International Conference on Geotechnical Engineering, held in Iraq in April 2024

• An integrated methodology for defining the tolerable level of risk for major engineering projects, Chengdu, China at th 21th Annual Conference of the Chinese Society for Rock Mechanics, China Rock 2024

• Principles for preparation of ground and design models related to rock masses in the light of second Eurocode 7 generation: GEO-EXPO Symposium in Bosnia and Herzegovina held in October 2024

• An integrated methodology for defining the tolerable level of risk for major engineering projects, Chengdu, China at

At a national level, the activities were performed within the frame of the Macedonian Association for Geotechnics (MAG). During the year, several events were organised together with National Chambers of Architects and Engineers. Several training courses were held during the year, where Milorad Jovanovski took part with presentations concerning Rock Mechanics aspects in the Second EC7 generation. Besides that, MAG organised 27th European Young Geotechnical Engineers Conference in June 2024 with participants from more than 30 countries, where he had the introductory presentation related to Geotechnics in Macedonia. In this period, the Macedonian NG started preparations for EUROCK2026, which will be held in Skopje, where Milorad Jovanovski is appointed as Chair of the event.

Besides these activities, in this period he was involved in other regular activities in a frame of ISRM Board and Council related to:

• Active participations in all ISRM Board meetings

• Activities as a member of the Technical Oversight Committee, together with Martin Grenon from Canada and Kiyoshi Kishida from Japan

• Evaluation of submissions for the Franklin Lecture,

• Check of submitted thesis for the Manuel Rocha,

• Activities related to FEDIGS initiatives for an International Conference

• Review of abstracts and articles for EUROCK 2024, ARMS13 and EUROCK2025.

• Preparation and submission of Report for the John Hudson Engineering Award as coordinator of commission with the following ISRM and Board members: Sérgio Fountoura, François Malan, Muriel Gasc-Barbier and Esteban Hormazábal.

Attendance at GEOXPO2023 in Bosnia and Herzegovina

Milorad Jovanovski, along with past VPs Ivan Vrkljan and Vojkan Jovicic, where conferred the title of Honourable Members of the Serbian Society for Civil Engineering

KIYOSHI KISHIDA

Kiyoshi Kishida serves as a member of the Technical Oversight Committee (TOC). In the last year, VP for North America Martin Grenon, VP at Large Milorad Jovanovski and him conducted the evaluation of the activities of each ISRM Commission in order to review the continuation of existing and to select newly proposed Commissions. He participated in several web meetings leading up to the Board Meeting held in Costa Rica in February 2024 where the Commissions names, objectives, and feasibility of each newly proposed was discussed. Ultimately, the Board finalized the list of Commissions that will be active from 2023 to 2027. Additionally, he was involved in collecting the activity reports from each Commissions over the past year, and in contacting a Commission that concluded its activities in October 2023 regarding the publication of their final report.

In February 2024, Kiyoshi Kishida delivered a research presentation in the workshop held in San José, Costa Rica, where he was deeply impressed by the beauty and charm of the country. He participated in the review of the manuscripts submitted for the Rocha Medal 2025 and submitted the respective evaluation scores, which was a wonderful opportunity to look at so many great dissertations.

In January 2024, Kiyoshi Kishida organized the JapanKorea Joint Symposium on Rock Engineering in Tokyo. The symposium was attended by ISRM President Seokwon Jeon and ISRM Vice President for Asia Ki-Bok Min. It was a great pleasure to see this event resume after being interrupted due to COVID-19.

In August 2024, he helped organizing an international joint seminar between China and Japan at Tongji University in Shangai, where he delivered a keynote lecture. The themes of this seminar were “Key Rock Mechanics Problems Involved in High-Level Radioactive Waste Geological Disposal Programs” and “The Fifth Young Scholars Seminar of Coupled Processes in Rock Masses.” He extends his gratitude to the Natural Science Foundation of China and to the Japan Society for the Promotion of Science for their support in hosting this event.

In November 2024, Kiyoshi Kishida attended CouFrac2024, held at Kyoto University Katsura Campus. This conference was hosted by the Japanese Society for Rock Mechanics and was designated as an ISRM Specialized Conference. The core organizing members were from the Commission on Coupled Thermal-Hydro-Mechanical-Chemical Processes in Fractured Rock, continuing the commission activities. He gave speeches during the banquet and closing ceremony. On a personal note, he performed the kagami-biraki (sake barrel opening) for the first time, which was a delightful experience, and thus he is grateful to the organizing committee for all their efforts.

Japan-Korea Joint Symposium on Rock Engineering 2023

Organization of the 6th Forum on Special Soil Mechanics and Engineering Practice for Young Scholars

Fengshou Zhang served as the chair of the Youth Working Committee of the CSRME in the 6th Forum on Special Soil Mechanics and Engineering Practice for Young Scholars held in Beijing from April 19 to 21, 2024. The forum attracted over 300 experts and representatives from universities, research institutes, and enterprises across China, providing a platform for in-depth discussions and exchanges on the latest advancements and practical applications in the field of special soil mechanics and engineering.

Development of the Journal ‘Rock Mechanics Bulletin’ Fengshou Zhang, serving as Executive Editor-in-Chief, has played a pivotal role in the establishment and growth of the journal Rock Mechanics Bulletin. He presided over the First Expanded Meeting of the Youth Editorial Board in Beijing on May 10, 2024, with over 100 young editors and industry experts in attendance. The event was guided by Prof. Jun Yang, the Executive Secretary-General of the Chinese Society for Rock Mechanics and Engineering (CSRME), further solidifying the journal’s foundation and future direction. The journal has been indexed in prestigious databases, including the Scopus and the Emerging Sources Citation Index (ESCI).

Organization of the ISRM Early Career Forum Special Event at China Rock 2024

On the morning of November 3, 2024, the International Society for Rock Mechanics and Rock Engineering (ISRM)-Early Career Forum (ECF) Special Event chaired by Fengshou Zhang was successfully held at the Tianfu International Conference Center in Chengdu, Sichuan Province, as part of the China Rock 2024 conference. Themed “Unleashing the Innovative Potential of Youth, Building a Future for Industry Development”, the forum aimed to bring together young scholars in rock mechanics from around the world to exchange innovative ideas and practical experiences. Distinguished attendees included ISRM Vice Presidents Ki-Bok Min and Milorad Jovanovski, former ISRM Vice President Qiang Yang, 2004 ISRM Rocha Medal recipient Prof. Giovanni Grasselli (University of Toronto, Canada), Prof. Steven D. Glaser (University of California, Berkeley) and Senior Geomechanics Engineer David Potyondy (Itasca Consulting Group). This special event marked a new endeavor by the CSRME on the international stage, providing a valuable platform for young talents and injecting fresh momentum into the innovation and development of rock mechanics and engineering.

FENGSHOU ZHANG

FRANKLIN LECTURE

Vikram Vishal | Bombay, India

GEOMECHANICAL CONSTRAINTS IN GEOLOGICAL CARBON DIOXIDE SEQUESTRATION

Carbon Capture and Storage (CCS) is a critical technology for mitigating climate change by reducing industrial carbon dioxide (CO2) emissions. However, the successful implementation of CCS projects is fraught with geomechanical challenges, including caprock integrity, fault reactivation, and induced seismicity. This paper explores the geomechanical risks associated with CO2 storage and highlights the research needed to address these challenges. The study discussed advanced geomechanical modeling, fault slip potential analysis, and multi-scale investigations to assess the stability of CO2 storage sites in India. The findings underscore the importance of integrating geomechanical risk assessment into CCS projects to ensure safe and effective CO2 storage. The paper also discusses the experimental studies that support this research, including triaxial testing, core flooding systems, and advanced imaging techniques

1. INTRODUCTION

The urgency of mitigating climate change has necessitated the adoption of CCS technologies. As one of the 14 Grand Challenges of the 21st century, CCS contributes to several Sustainable Development Goals (SDGs), including climate action, clean energy, and industry innovation. With India projected to account for approximately 14% of global CCS by 2070 [1], this study investigates the potential of CCS deployment, challenges, and research gaps in the Indian context.

India, as one of the fastest-growing economies, faces a dual challenge of meeting its energy demands while reducing its carbon footprint [2]. The country’s reliance on fossil fuels, particularly coal, for energy generation makes CCS a crucial technology for achieving its climate goals. Even though there is a huge CO2 storage potential in Indian sedimentary basins (~300 Gt), the deployment of CCS in India is still in its nascent stages, with significant technical, regulatory, and economic barriers [3, 4]. This paper explores the experimental and numerical studies involved in advancing CCS research, particularly in addressing geomechanical challenges, which are critical for the safe and effective storage of CO2. The paper further discusses advanced geomechanical modeling, fault slip potential analysis, and multi-scale investigations to assess the stability of CO2 storage sites in India.

2. GEOMECHANICAL CHALLENGES IN CO2 STORAGE

2.1 Caprock integrity

Caprock integrity is a critical factor in ensuring the long-term containment of CO2. The caprock acts as a seal, preventing the upward migration of CO2 into overlying formations [5]. However, the injection of CO2 can alter the stress state of the caprock, potentially leading to failure. The sealing capacity of caprocks is determined by their capillary threshold pressure,

which depends on factors such as wettability, interfacial tension, and effective hydraulic radius [6]. Laboratory studies are required to assess the capillary threshold pressure of caprocks to determine their ability to trap CO2. High capillary pressures indicate strong sealing capabilities, which are crucial for preventing leakage.

2.2 Fault reactivation

Fault reactivation is another significant geomechanical risk associated with CO2 storage. The injection of CO2 increases pore pressure in the reservoir, which can reduce the effective stress on faults, potentially leading to slip [7]. Fault reactivation can create pathways for CO2 leakage and induce seismicity, posing environmental and safety risks.

2.3 Induced seismicity

Induced seismicity is a major concern in CCS projects, as the injection of CO2 can alter the stress state of the subsurface, potentially triggering earthquakes [8]. The risk of induced seismicity is particularly high in regions with pre-existing faults and fractures [9]. Numerical models need to be developed to predict stress changes in response to CO2 injection and evaluate the potential for fault activation [10]. The models should incorporate geomechanical parameters such as overpressure, stress anisotropy, and pore-pressure instability to assess the stability of faults and fractures. The models inform strategic site selection and real-time monitoring which can mitigate potential seismic hazards [11].

3. RISK ASSESSMENT AND MANAGEMENT

Ensuring CO2 containment requires a comprehensive risk assessment and management framework. Risk assessment is a critical component of CCS projects, as it helps to identify and mitigate potential hazards that could compromise the safety and effectiveness of CO2 storage. Potential leakage pathways, including faults and fractures, are identified through probabilistic fault slip potential analysis. Additionally, caprock integrity assessments and induced seismicity simulations are conducted to evaluate the risks associated with long-term CO2 storage [7].

The risk assessment and management in CO2 storage employs an interdisciplinary approach integrating geological, geomechanical, and reservoir modeling to assess CO2 storage.

The workflow includes multiple steps characterizing the reservoir and assessing the technical risks (Fig. 1):

3.1 Site-screening criteria

The selection of suitable CO2 storage sites requires a systematic approach based on geological and reservoir characteristics. Existing global screening criteria for CCS, are reviewed and tailored to Indian reservoirs. Factors such as porosity, permeability, reservoir depth, and caprock integrity are considered to determine potential sites for safe and effective CO2 storage. The site-screening process involves a multi-step evaluation, including geological mapping, seismic surveys, and well-logging data analysis, to identify reservoirs with optimal storage capacity and minimal risk of leakage [12].

3.2 Multi-scale investigations

Multi-scale investigations are required to understand the geomechanical behavior of CO2 storage sites. They span from the regional scale to the core and pore scale. At the regional scale, seismic data and well logs are used to map faults and fractures within the reservoir. At the core scale, laboratorybased 1D core flooding experiments are conducted to assess reservoir response to CO2 injection. These tests evaluate essential reservoir parameters, including relative permeability, porosity, and fluid displacement efficiency, which are crucial for optimizing CO2 storage strategies and ensuring effective sequestration [13]. Core flooding experiments provide valuable insights into the interaction between CO2 and reservoir fluids, helping to design injection protocols that maximize storage efficiency. At the pore scale, advanced imaging techniques such as X-ray computed tomography (CT) are used to study the microstructure of rocks and the interaction between CO2 and reservoir fluids (Fig. 2).

3.3

Geomechanical modeling

Understanding subsurface rock behavior under CO2 injection conditions is crucial to mitigating risks such as caprock failure and induced seismicity. Well data is used to develop 1D geomechanical models, and triaxial tests on reservoir cores are performed to calibrate them (Fig. 3). These models are further expanded into 3D geomechanical frameworks by integrating seismic and petrophysical data. Geomechanical modeling is essential for assessing the stability of the reservoir and caprock during CO2 injection, as well as for predicting potential geomechanical risks such as fault reactivation and induced seismicity.

Fig. 2 - Pore network modelling using X-ray CT.

Fig. 1 - Simplified workflow for geomechanical risk assessment in CO2 storage.

Fault slip potential using Monte Carlo probabilistic analysis. The likelihood of induced seismicity due to CO2 injection is assessed through fault slip potential (FSP) analysis (Fig. 4).

By simulating varying pore pressures and stress conditions, potential fault reactivation risks are identified, helping optimize injection strategies [14]. The results of the FSP

simulation show the evolution of pore pressure and fault slip potential over time, helping to optimize injection strategies and mitigate risks. The probabilistic approach allows for a more accurate assessment of fault stability under different injection scenarios [15].

Fig. 3 - Integrated 1D geomechanical model, including calculated principal stresses and geomechanical parameters, using well log data.

Fig. 4 - FSP analysis for fault reactivation. On the left, the faults and pore pressure map are shown, and the evolution of FSP with time is shown on the right.

Seal integrity of caprocks through capillary pressure assessments. Laboratory studies assess the capillary threshold pressure of caprocks to determine their ability to trap CO2 High capillary pressures indicate strong sealing capabilities, crucial for preventing leakage into overlying formations. Caprock integrity is a critical factor in ensuring the long-term containment of CO2, and capillary pressure assessments provide valuable insights into the sealing capacity of caprocks.

4. CHALLENGES AND FUTURE DIRECTIONS

Despite the potential of CCS in India, several challenges persist. Further research is required to address knowledge gaps in subsurface characterization, geomechanical stability, and risk mitigation strategies. Collaborative efforts between academia and industry are crucial for advancing CCS technologies [16]. Technical uncertainties, particularly in the area of geomechanics, pose significant challenges to CCS deployment, and ongoing research is essential for addressing these challenges.

5. CONCLUSION

CCS is an unavoidable strategy for climate change mitigation, with significant potential for CO2 storage in India's sedimentary basins. The research methods outlined in this paper provide critical insights into site selection, storage feasibility, and geomechanical risks. With strengthened industry-academia partnerships, India can advance CCS technologies and contribute significantly to global carbon sequestration efforts. The geomechanical challenges associated with CO2 storage, such as caprock integrity, fault reactivation, and induced seismicity, are critical areas of research, and IIT Bombay is at the forefront of addressing these challenges through innovative methodologies and collaborative research initiatives.

REFERENCES

IEA (2020) CCUS in Clean Energy Transitions. Paris

Singh U, Vishal V, Garg A (2024) CCUS in India: bridging the gap between action and ambition. Prog Energy 6:023004. https://doi.org/10.1088/2516-1083/AD31B6

Verma Y, Vishal V (2021) Role of Geological Carbon-Dioxide sequestration in India’s efforts towards Net Zero Emissions. MGMI News J 47:40–49

Vishal V, Verma Y, Chandra D, Ashok D (2021) A systematic capacity assessment and classification of geologic CO2 storage systems in India. Int J Greenh Gas Control 111:103458. https://doi.org/10.1016/j.ijggc.2021.103458

Verma Y, Vishal V (2024) Modeling and simulation of CO2 geological storage. In: Rahimpour MR, Makarem MA, Meshksar M, Bakhtyari A (eds) Advances and Technology Development in Greenhouse Gases: Emission, Capture and ConversionProcess Modelling and Simulation. Elsevier, pp 153–175

Vilarrasa V, Makhnenko RY (2017) Caprock Integrity and Induced Seismicity from Laboratory and Numerical Experiments. Energy Procedia 125:494–503. https://doi. org/10.1016/j.egypro.2017.08.172

Verma Y, Vishal V, Ranjith PG (2021) Sensitivity Analysis of Geomechanical Constraints in CO2 Storage to Screen Potential Sites in Deep Saline Aquifers. Front Clim 3:1–22. https://doi.org/10.3389/fclim.2021.720959

Zoback MD (2007) Reservoir Geomechanics

Cheng Y, Liu W, Xu T, Zhang Y, Zhang X, Xing Y, Feng B, Xia Y (2023) Seismicity induced by geological CO2 storage: A review. Earth-Science Rev 239:104369. https://doi. org/10.1016/j.earscirev.2023.104369

Vishal V, Singh TN (2016) Geologic carbon sequestration: Understanding reservoir behavior. Springer International Publishing

Verdon JP, Stork AL (2016) Carbon capture and storage, geomechanics and induced seismic activity. J Rock Mech Geotech Eng 8:928–935. https://doi.org/10.1016/j. jrmge.2016.06.004

Callas C, Davis JS, Saltzer SD, Hashemi SS, Wen G, Gold PO, Zoback MD, Benson SM, Kovscek AR (2024) Criteria and workflow for selecting saline formations for carbon storage. Int J Greenh Gas Control 135:104138. https://doi.org/10.1016/J. IJGGC.2024.104138

Xu L, Li Q, Myers M, White C, Tan Y (2020) Experimental and numerical investigation of supercritical CO2 migration in sandstone with multiple clay interlayers. Int J Greenh Gas Control 104. https://doi.org/10.1016/j.ijggc.2020.103194

Verma Y, Vishal V, Ranjith P (2021) Risk analysis of injectioninduced seismicity associated with geological CO2 storage through enhanced oil recovery. In: AGU Fall meeting 2021. AGU, New Orleans, LA

Verma Y, Vishal V, PG R (2022) Effect of injection strategy on Induced Seismicity risk during CO2 storage. In: AGU Fall Meeting 2022. Authorea, Chicago

Vishal V, Chandra D, Singh U, Verma Y (2021) Understanding initial opportunities and key challenges for CCUS deployment in India at scale. Resour Conserv Recycl 175:105829. https:// doi.org/10.1016/j.resconrec.2021.105829

ROCHA MEDAL LECTURE

Kazuki Sawayama | Kyoto Japan

RELATIONSHIPS BETWEEN FRACTURE FLOW BEHAVIORS AND GEOPHYSICAL PROPERTIES: TOWARDS INDIRECT MONITORING OF FRACTURED RESERVOIRS

Fractures in an impermeable rock mass predominantly constrain the bulk flow of a system. Consequently, the fluid flow behavior in fractures and its temporal changes require thorough examination to characterize subsurface mass and heat transport. Although the hydraulic properties of rock fractures have been extensively investigated with respect to various fracture microstructures, the in situ prediction of permeability remains unfeasible using these classical models. Field geophysical observations have indicated that electrical and seismic properties can detect subsurface fractures. Despite the significance of interpreting such observational data, experimental and numerical data for these properties of rock fractures are limited. Simultaneous measurements of hydraulic-electrical-elastic properties utilizing the Digital Rock Physics approach may elucidate the nature of variations in rock properties and their relationships. This study aims to establish a rock physics model to evaluate permeability for single fractured rock mass utilizing electrical resistivity and seismic velocity. It would be beneficial if alterations in fluid flow behavior could be monitored using remotely acquired geophysical data through the established model.

1. INTRODUCTION

Fluid flow in rock fractures is of significant importance for a wide range of subsurface anthropogenic activities, including fluid reservoirs (geothermal and shale oil), carbon capture and storage, radioactive waste disposal, and seismic hazard mitigation. Despite this significance, the fluid flow behavior in subsurface fractures has not yet been well characterized. The complexity of the fracture flow system arises from the fracture roughness that governs the preferential flow path within a fracture (i.e., channeling flow). These features of fracture roughness may impede the establishment of a universal model of fracture flow. The primary objective of studies on fracture flow is to develop a robust model that characterizes flow systems in numerous fields, such as geothermal and shale oil resources, geological storage or disposal, and seismicity.

Given the inability to directly observe subsurface structures and crustal fluids, geophysical observation techniques have been employed to image and monitor them. This study focused on electrical (or electromagnetic) and seismic methods, as these properties are susceptible to fractured systems, fluid distribution, and their temporal changes. These changes in geophysical properties are induced by pressure changes, which also affect the fracture flow. Consequently, geophysical monitoring can potentially detect changes in permeability enhancement associated with fracture aperture changes. However, no rock physics model currently exists to link the hydraulic and geophysical properties of fractured rock masses. To monitor the fluid flow behavior with geophysical data, it is necessary to investigate the fundamental relationships between the hydraulic and geophysical properties of rock fractures. This study investigated the fracture permeability, electrical resistivity, and elastic wave velocity of rock fractures through

a combination of experimental and numerical approaches. The experimental approach, particularly simultaneous measurements of multiple rock properties, cannot be conducted without sophisticated apparatus, and is generally challenging to apply to fractured rock samples. Fractures possess unique characteristics, and thus rock properties will vary even within the same lithology. Based on this, most studies have utilized a numerical approach to calculate hydraulic flow properties. However, they have primarily considered two-dimensional flow on the fracture surfaces (i.e., the Reynolds equation). Threedimensional hydraulic and electrical flows in fracture apertures have not yet been investigated comprehensively. To constrain the simultaneous changes in hydraulic and geophysical properties, this study utilized recent advances in digital rock physics. One of the most significant features of digital rock simulation is the ability to evaluate multiple properties of the same sample while visualizing its microstructure. This study established a novel approach to investigate multiple rock properties of fractures. For the three-dimensional fluid flow simulation, this study employed the lattice Boltzmann method (LBM), which is suitable for modeling heterogeneous three-dimensional fluid flow. The electrical and elastic properties were analyzed using the finite element method (FEM). Based on these methods, the three-dimensional local flow, electrical current, stress, strain, and associated elastic energy are visualized, which are difficult to observe in laboratory experiments or in the field. These microscopic investigations enable the discussion of the nature of changes in rock properties and their respective relationships. Finally, the rock physics model is proposed to evaluate permeability for single fractured rock mass through the utilization of electrical resistivity and seismic velocity measurements.

2. MATERIAL AND METHOD

2.1 Sample

Laboratory experiments and numerical simulations were conducted utilizing cylindrical fractured samples composed of granite and andesite. For the granite sample, two distinct specimens were employed: one characterized by a “rough” surface exhibiting higher roughness (s=1.7 mm), and the other featuring a “smooth” surface with lower roughness (s=1.3 mm). In this context, the surface roughness, denoted as s, is defined as the root-mean-square height of fracture surface topographies, representing the standard deviation of surface height. The pyroxene andesite sample was obtained from a natural sheared fracture within a geothermal area.

The fracture topographies of these samples were acquired using a one-shot 3D measuring macroscope (Keyence, VR3050) with a grid of 23.433 µm square cells. The mapped fracture surfaces were subsequently analyzed for their fractal characteristics in each sample fracture.

2.2 Experiment

Following the mapping of fracture surfaces, the specimen was restored to its original configuration. Subsequently, simultaneous measurements encompassing fluid flow, electrical impedance, and elastic wave velocity were conducted under varying effective normal stress conditions (Fig. 1). The independent control of pore-inlet, pore-outlet, and confiningoil pressures was executed utilizing ISCO syringe pumps. The brine (1 wt.% KCl solution) was injected into the jacketed samples under confining pressures ranging from 5 to 30 MPa and pore pressures varying between 2 and 20 MPa. From the measured flow rate Q, bulk permeability k in each stress state was calculated using the Darcy’s law

where A , µ, and ∇P denote the cross-sectional area, viscosity, and pressure gradient, respectively.

Resistivity was measured utilizing the electrical impedance method via a four-terminal experimental setup. The current and voltage electrodes were made from a silver net ribbon with an AgCl-baked coating (Sawayama et al., 2018). The conductivity of the fluid medium significantly exceeded the surface conduction effects within the rock matrix. Electrical impedance Z was determined by

where Z ' and Z " denote in-phase (real) and quadrature (imaginary) impedance, respectively, and θ is the phase angle. The real and imaginary components of electrical impedance were measured utilizing an Impedance Analyzer SI 1260A (Solartron Analytical, Ltd.) across a frequency spectrum ranging from 10-2 to 105 Hz, under a constant applied alternating current voltage of 30 mV. Subsequently, bulk resistivity ρ was calculated from the real component of impedance and the surface area-to-length ratio A/L as follows:

The measurement of elastic waves was conducted utilizing the pulse transmission method. The input trigger pulse was configured with a frequency of 250 kHz and an amplitude of 10 Vp-p. The acquired waveforms were subjected to stacking over 200 iterations. The first arrival times of the P-wave were analyzed using the Akaike information criterion (AIC), wherein the global minimum of the AIC function corresponds to the onset time of a signal. Subsequently, P-wave velocity was calculated based on travel time in conjunction with the distance between the transmitter and receiver transducers.

2.3 Digital fracture simulations

From the mapped surface topographies in each sample, this study generated three-dimensional digital fracture models through numerical pairing. In addition to the natural fracture models (Sawayama et al., 2021a), this study also prepared upscaled synthetic fractures with varying fracture length scales (24 mm, 48 mm, 96 mm, and 144 mm) based on Matsuki et al. (2006) from the natural rough surfaces of the andesite to verify the scale dependence of the rock properties (Sawayama et al., 2021b). To apply the results of the laboratory-scale investigations to field-scale predictions, the fractal characteristics of the real rock fracture surfaces were incorporated into the modeling (Fig. 2). A pair of correlated fractal surfaces is initially generated by inverse Fourier transforming the Fourier components based on fractional Brownian motion (Sawayama et al., 2021b). This method reproduces a self-affine fractal surface with identical amplitude and different relative phase for each fracture surface. Digital fracture models are created by numerically pairing the synthetic fracture walls with varying values of aperture closure, through solving the elasto-plastic deformation of the asperities (Sawayama et al., 2023a).

A series of numerical simulations were subsequently performed on digitized fractures in a system of 0.1 mm cubic voxels. The three-dimensional fracture flow was simulated utilizing the Lattice Boltzmann Method (LBM). The fundamental principle of LBM is to model the fluid as a group of particles

Fig. 1 - System outline of the simultaneous measurement of fluid flow, electrical impedance, and elastic wave velocity (modified after Sawayama et al., 2018).

that adhere to the same conservation laws. The local fluid flow can thus be simulated as streaming and collision of these particles. The Boltzmann equation for the system with no external force can be expressed as

where e is the microscopic velocities of particles. By discretizing Eq. (4) in space x and time t, we can find the following lattice Boltzmann equation

where ∆t is the time step and fi(x,t) is the particle distribution function that represents the probability of finding a particle at node x and time t. The Ωi shows collision operators, whereas the difference between a left side and the first term in a right side of Eq. (5) indicates the streaming part. This study adopted D3Q19 lattice and MRT (multiple relaxation time) model. At the fracture surfaces, bounce-back boundaries (a no-slip scheme at fluid-solid interfaces) were implemented. Provision of a constant body force from the inlet to the outlet boundaries and the periodic boundary along the fracture plane enabled us to simulate the fluid flow and thereby estimate permeability along the fracture (Fig. 2).

From the heterogeneous water distribution estimated through the LBM simulation, the 3D electric field along the fracture filled with brine was simulated based on the law of charge conservation:

where the current density J is expressed by Ohm’s law using the electric conductivity σ

Given an electric field e=-∇ϕ, we derive the following Laplace equation.

This study numerically solves this governing equation via finite-element method by minimizing the gradient of the electric energy with respect to ϕ (Sawayama et al., 2021b). Resistivity is then estimated by obtained electric current and applied voltage in parallel to the flow direction.

The elastic wave velocity in the direction perpendicular to the fracture plane was estimated from the simulated static elasticity under the triaxial stress state. When a fracture occurs in a stressed homogeneous material, the interaction energy between stress and fracture is generated, which increases the elastic energy E. Sawayama et al. (2022) propose a method that directly calculates the quasi-static changes in E of the fractured material. The stiffness tensor Cijkl is defined as the second derivative of E with respect to the surface strain εijA:

The conventional FEM calculation solves the microscopic stress and strain according to an arbitrary input macroscopic strain. However, a constant value of macroscopic strain gives Cijkl in the isostrain case (upper bound). To incorporate the constant stress assumption into the conventional FEM, Sawayama et al. (2022) adopted the numerical self-consistent (NSC) scheme. In this approach, the macroscopic strain was updated in a stepwise manner to keep the initially assumed macroscopic stress constant with increasing mean aperture. This integrated approach using FEM and NSC methods allows us to solve for reasonable changes in the anisotropic shape of Cijkl , which is not possible with a conventional FEM approach. Since a fractured rock can be assumed to be transversely isotropic along the z-axis (i.e., perpendicular to the fracture plane), the target Cijkl has hexagonal symmetry:

From this, the P-wave velocity V p and the S-wave velocity V s in the direction perpendicular to the fracture plane were calculated as:

here d is the arithmetic mean of the solid and pore water densities. In the analysis, a periodic boundary was imposed in all directions, simulating an infinitely large model with a constant fracture density in the vertical direction (i.e., the number of fractures per unit thickness). The elastic properties of the solids for the numerical simulation are determined based on velocity measurements of rocks under high-pressure conditions (Table 1). Note that this derivation results in elastic constants that assumes a host material formed by the minerals plus the stiff pores (Sawayama et al., 2024a).

Note that the discretization error and stochastic fluctuations were evaluated using models with different voxel sizes: 24 × 24 mm fracture models utilizing cubic systems with 0.05, 0.1, and 0.2 mm voxels, demonstrating that the 0.1 mm voxel results are sufficient. Moreover, the simulated results generally

Fig. 2 - Model setup of the 3D digital fracture simulation. Fluid flow and applied voltage are defined as parallel to the fracture plane, whereas elastic wave velocity is defined as perpendicular to the fracture plane. Both the lattice Boltzmann simulation and finite-element modeling adopt a periodic boundary condition (Sawayama et al., 2021a).

corroborated the experimental results and predicted values from the equivalent channel model (Sawayama et al. 2021b, 2022).

Table 1. Physical properties used for FEM. σ, K , and G denote the electrical conductivity, bulk modulus, and shear modulus, respectively.

* Sea water

** Experimental result of the resistivity measurement under dry condition (Sawayama et al., 2019)

*** Based on P- and S-wave velocity measurements under dry and high confining pressure (200 MPa)

4. EVOLUTION OF LOCAL-FLOW BEHAVIOR

Figure 3 illustrates the three-dimensional fluid flow paths on the representative fracture surfaces. Flow paths in all models are channelized by asperity contacts (i.e., preferential flow paths). As the fracture aperture decreases, both the flow velocity and the number of preferential flow paths diminish. Permeability in each model was calculated from these simulated flow velocities for comparison with the experimental results (Fig. 4). Plots of the logarithmic permeability against stress demonstrate a change with increasing effective normal stress from curving trends to linear trends. Figures 4c and 4d present representative simulation results for the distribution of apertures (in grayscale) and associated flow rates (in color) through the smooth and rough fractures, respectively. At

low stresses, preferential flow paths form that cover most of the area with open (non-zero) apertures (images i in Fig. 4). Isolated apertures also form, initially few in number, that are surrounded by contacting asperities (zero aperture points), where the fluid is stagnant (white patches in Fig. 4c, d).

As stress increases, larger fractions of the fracture surfaces are in contact, and consequently, the dominant flow paths decrease in number. As the dominant flow paths become less significant, the flow paths from the inlet to outlet are progressively disconnected (images iii and iv in Fig. 4). Accordingly, the permeability-stress relationship includes a transition: logarithmic permeability changes exponentially with stress while the flow paths are connected (images i and ii) and linearly while the flow paths are disconnected (images iii and iv). The stress level where this change occurs can be defined as the hydraulic percolation threshold σHPT, which signifies the creation of continuous flow paths through rocks. Roughness does not appear to significantly affect this threshold (see Fig. 5a).

Figure 5a depicts the vectors of hydraulic flow (in blue) and electrical flow (in red) superimposed at the same position to facilitate comparison of their respective path distributions. These two-dimensional vectors represent summations of the vectors in all cross sections in the z-direction (normal to the fracture plane) and are displayed on the aperture structure (in grayscale). While hydraulic flow and electric current predominantly traverse areas of non-zero aperture, the electric current exhibits a greater number of paths than the hydraulic flow. This observation suggests that hydraulic flow is more significantly influenced by contacting asperities than electric current. The disparate sensitivities of hydraulic and electric processes to alterations in aperture are the primary cause of their divergent streamlines. According to Ohm's law and the cubic law, the electric current exhibits a linear dependence on the aperture, while the flow rate is proportional to the cube of

Fig. 3 - Three-dimensional flow paths calculated by the lattice Boltzmann simulation on the surface of the (a–c) smooth and (d–f) rough fracture under various effective normal stress (σeff). Flow velocity (in color online) is illustrated on the footwall of each fracture surface (Sawayama et al., 2021a).

the aperture. Nevertheless, cross-sectional analyses of flow rate (Fig. 5b) and electric current (Fig. 5c) along line X–Xş in Fig. 5a demonstrate that the simulation model, in certain instances, yields lower fluxes in larger apertures and higher fluxes in smaller apertures. This observation suggests that local apertures are not the sole determinants of local hydraulic and electrical transport processes in rough-walled fractures. The connectivity of the path network also exerts a significant influence on local transport phenomena. This characteristic is notably absent in the local parallel-plate model of electrical conductance and flow rate.

Fig. 4 - Experimental and simulated fracture permeabilities with increasing effective normal stress of the (a) smooth and (b) rough fractures and representative images derived from the simulation showing fracture flow distribution (color) within the heterogeneous aperture distribution (grayscale) with aperture closure of the (c) smooth and (d) rough fractures. Black and white diamonds in (a) and (b) represent experimental and simulated results, respectively. Red diamonds in (a) and (b) are the representative results that are illustrated in (c) and (d). The normalized flow in (c) and (d) represents the summation of flow rates in every z-direction (direction normal to the fracture plane), normalized by the maximum value in each condition, and the regions with <1% of the maximum flow rate are colorless (Sawayama et al., 2021a).

Fig. 5 (a) - Map of the local fracture aperture d (grayscale) showing streamlines for hydraulic flow (blue) and electrical flow (red). The map is 24 mm square and the mean aperture is 0.11 mm. (b) Cross-sectional profile on line X–X'showing the hydraulic flow in the fracture. (c) Crosssectional profile on line X–X' showing the electrical flow in the fracture. Note that some high-flux channels in both flow rate and electric current appear in narrow apertures, and some low-flux channels appear in wide apertures (Sawayama et al., 2021b).

5. CHANGES IN ROCK PHYSICAL PROPERTIES AS ELEVATED STRESS

Based on the aforementioned local behaviors, this study subsequently calculated the evolution of several rock properties in response to stress changes (Fig. 6). Permeability and resistivity exhibit a linear relationship at stresses increase, but deviate from linearity at lower stress levels. Neither property demonstrates dependence on fracture roughness. On the other hand, elastic wave velocity varies significantly with roughness, and in contrast to porous rocks, there is no distinct correlation between velocity and porosity; even at equivalent porosity values (for instance, ~1.2%), P- and S-wave velocities exhibit variations. Although the roughness-related variation in P-wave velocity exceeds that of S-wave velocity, the stress dependencies of Pand S-wave velocities demonstrate similar trends.

Fig. 7 Sawatama et al.

Fig. 6 - Graphs showing changes in (a) permeability, (b) resistivity, (c) elastic wave velocity and (d) porosity in relation to effective normal stress. Dashed lines are extrapolations from the data in the regions of disconnected flow (gray), as defined by the value of σHPT. Gray symbols in (c) and (d) (green in the online version) represent pairs of data points that have comparable porosity (~1.2%) (Sawayama et al., 2021a).

6. CROSS-PROPERTY RELATIONSHIPS

Figure 7a presents plots examining the initial hypothesis regarding the relationship between hydraulic-electricalelastic properties. The relationship of P-wave velocity with log permeability exhibits sensitivity to roughness, whereas resistivity demonstrates a clear relationship with permeability on a log-log basis that remains consistent across varying roughness levels. Permeability and resistivity are generally sensitive to pore connectivity, and thus their roughnessindependent tendencies may suggest that connectivity is unlikely to change with differences in roughness even at the same stress.

Both hydraulic and electrical flows become highly channelized with the growth of contacting asperities (Figs. 4, 5). These flow paths diminish in number with aperture closure as the contact area and isolated apertures increase. It is noteworthy that electric current paths exhibit a more uniform distribution in the fracture compared to fluid flow paths. This discrepancy arises from the differential sensitivity of electrical and hydraulic flows to aperture. While flow rate decreases more significantly with aperture closure and local flow directions exhibit greater deviations from the global flow direction (i.e., high tortuosity), local current directions show less deviation from the global flow direction due to the reduced sensitivity of electric current to aperture. To evaluate the degree of these path deviations, a weighted average of the local tortuosity was calculated from the local flow directions. The results indicated that the tortuosity of flow paths remains constant across varying roughness levels under the conditions of this study (Fig. 7b). Further analysis utilizing different fracture sizes, surface roughness, and shear displacement demonstrated that global flow connectivity and local tortuosity are mutually correlated (Sawayama et al., 2023a).

Fig. 7 - Graphs showing correlations between permeability and geophysical properties. Solid and open symbols represent smooth and rough fractures, respectively (Sawayama 2024).

The roughness dependence of the velocity change results from variations in porosity and contact area, with higher velocities observed in samples exhibiting lower porosity or larger contact area, even under identical stress conditions. Furthermore, diverse roughness characteristics generate variations in the size of fracture asperity contacts, which also influence the velocity difference. As an analogy to the crack model, the present fractured sample demonstrates stress concentration on small asperities, which are predominant in smooth fractures; consequently, the velocity difference may also be attributed to the size variation of contacting asperities (Sawayama et al., 2021a).

Having established that permeability and resistivity are independent of roughness, the discussion is subsequently extended to the scaling law between these parameters. Despite the dependencies of fracture size, shear displacement, and surface roughness characteristics on permeability and resistivity, this study revealed that their respective correlations exhibit stable trends irrespective of these characteristics (Fig. 8). The relationship between permeability k and the formation factor (hereafter referred to as the k–F relationship) can be correlated as follows with two different slopes α

Note that the formation factor F is the ratio of bulk resistivity ρb to the fluid resistivity ρw, (F=ρb / ρw ) such that the effects of both the temperature and salinity on fluid resistivity can be neglected. Overall, the slope α remains constant regardless of the different fracture geometric characteristics. Based on the equivalent channel model, the slope α represents the sensitivity of the tortuosity against aperture closure and is bounded between values of 1 and 3. To this point, the inflection of the

k–F relationship (at k =~10−11.5) may represent the transition of their different sensitivities to tortuosity under fully connected and partially disconnected flow regimes, i.e., the effect of percolation because of the channeling of the limited flow paths.

Fig. 8 - Correlation between formation factor and permeability compiled for all fracture datasets. The symbols’ color and shape represent different fracture length scales, shear displacement, roughness, and fractal dimension values. The solid and dashed lines denote prediction lines based on Eq. (12) for α = 2.7 and α = 1.0, respectively (Sawayama et al., 2023a).

The results for higher permeability (i.e., the fully connected flow regime) are plotted on the straight line of α = 2.7 (close to 3), which indicates that the change in tortuosity is highly sensitive to aperture change. Conversely, the results demonstrate α = 1.0 below the percolation threshold (i.e., the partially disconnected flow regime). This represents the lower limit expected based on the equivalent channel model, suggesting that the change in tortuosity is insensitive to aperture closure. In both scenarios, these findings may imply that the permeability change can be estimated without knowledge of the absolute permeability value. This outcome contradicts the linear results obtained previously using a saw-cut fracture sample; however, this non-linear relationship is consistent with a recent experiment utilizing roughwalled fractures (Sawayama and So, 2025). The divergent trends of the k-F relationships in the connected and less connected regimes indicate varying sensitivity of resistivity to permeability changes in response to connectivity within subsurface fractures. This suggests that resistivity monitoring may be more effective in detecting permeability changes in connected fractures

The changes in elastic wave velocities under elevated stress could be correlated with fracture permeability in terms of aperture (Sawayama et al., 2022). The predicted relationship between fracture permeability and elastic wave velocity (i.e., the k-V relationship) was plotted in Figure 9 (b) and (c). The k-V relationship can be ultimately modeled as follows:

Fig. 9 - Graphs of fracture permeability versus (a) P-wave velocity, and (b) S-wave velocity. The green and blue lines denote the predicted relationships based on Eqs (13) and (14) (modified after Sawayama 2024).

where k' , Vp', and Vs ' are arbitrary reference values of permeability, and P- and S-wave velocities, respectively. The empirical parameters γp and γs represent the coefficients for the k–V p and k–Vs relationships for a single fracture, respectively. The predicted lines using γp = 3000 and γs = 2500 are also shown in Fig. 9. The predicted k–V relationship is consistent with the simulation results, which is irrelative to the contact state, and constant in fractures with the same fractal characteristics. Although the empirical parameter γ can vary with roughness, it can be determined from the k–V relationship for a single fracture. This finding implies that investigations of small-scale single fractures and the k–V relationship can be extrapolated to multiple fractures in natural settings. Therefore, velocity monitoring can potentially evaluate changes in fracture permeability.

7. IMPLICATIONS

The field observations have detected unusual changes of rock properties that cannot be explained by these experimental results using intact rocks. The presence of fractures may account for these discrepancies. To investigate this issue, this study compiled the results on the evolution of rock properties in single fractures and compared them with the changes in flow rate distribution within the fracture. These changes in rock properties can be categorized as roughness-dependent (Fig. 10a) or roughness-independent (Fig. 10b). Elastic wave velocity and flow area are both roughness-dependent, thus we can distinguish separate mechanical percolation thresholds for smooth fractures (σMPT) and rough fractures (σ 'MPT), defined

in both cases as the stress at which velocity reaches 90% of its maximum value (Fig. 10a). Because σMPT is smaller than σ 'MPT, velocity increases more sharply with stress in smooth fractures than in rough fractures. The difference arises from a discrepancy in the heterogeneous aperture distribution (Fig. 10c). Resistivity and permeability are both roughness independent (Fig. 10b).

The lattice Boltzmann fluid flow simulation revealed that the fracture flow pattern undergoes transitions through three stages as effective normal stress increases (Fig. 10c). At lower stresses, Stage I represents aperture-dependent flow, where fluid flows within most of the aperture, and the flow area decreases as the mean aperture decreases. Stage II represents aperture-independent flow, in which isolated apertures appear and become areas without flow. Although elastic wave velocity remains nearly constant with rising stress, permeability and resistivity change exponentially because the flow paths are still connected. These attributes are thus less sensitive to the spatial distribution of asperity contacts. In Stage III, the flow paths become disconnected and result in disconnected flow. In this stage, the areas without flow become a significant fraction of the fracture area. Because Stage II begins when the velocity ceases to change with rising stress, the transition from Stage I to II can be detected by velocity monitoring, whereas resistivity is sensitive to the transition from Stage II to III. If crustal stress can be considered constant (i.e., on relatively short timescales), then changes in the fracture flow pattern with effective normal stress represent changes in pore pressure. This finding demonstrates potential in two applications.

One application involves the evolution of fluid flow along faults, which is part of the fault reactivation cycle triggered by pore pressure perturbations. The model of Stage I generally reproduces observations of high permeability, low resistivity, and low seismic velocity resulting from high pore pressures associated with earthquakes. The changes in elastic wave velocity and permeability from Stage I to II (Figs. 10a and b) exhibit good agreement with observations after earthquakes. Moreover, during Stage II, seismic

velocity remains nearly constant after healing stabilizes the mechanical properties of faults. Fault healing eventually leads to large areas of little or no flow (Stages II and III), where mineral precipitation is favored. Pore pressure changes following earthquakes, triggered by several mechanisms such as mineral precipitation, lead rapidly to decreases in seismic velocity, increases in permeability, and decreases in resistivity, after which all of these properties recover. This suggests that fracture flow patterns return to their initial condition (Stage I). Thus, the inferred transitions in the fracture flow pattern may elucidate how the cycle of earthquake recurrence is correlated with geophysical observations, complementing the fault-valve model.

The presence and reactivation of mesoscale fractures and the associated changes in permeability are significant factors in the development of enhanced geothermal systems (EGS). In practice, resistivity observations in EGS projects detect resistivity changes (approximately a few percent) that are associated with the hydraulic stimulation of preexisting fault systems. Under the assumption that α takes a value between 1 and 3 in Eq. (12), these resistivity changes correspond to increases in permeability ranging from a few to several tens of percent. It is noteworthy that the variability of α is entirely

(a) Roughness-dependent properties

(b) Roughness-independent properties

Fig. 10 - Schematic diagram of changes with respect to pressure in (a) roughness-dependent properties and (b) roughness-independent properties and (c) schematic images of the three-stage transition of fracture flow patterns. All rock physical properties in (a) and (b) are normalized based on computed results. Gray lines in (a) represent mechanical percolation thresholds σMPT and σ ' MPT of smooth and rough fractures, respectively, which distinguish aperture-dependent and aperture-independent flows (Stages I and II). The gray line in (b) represents the hydraulic percolation threshold σMPT, which represents the boundary between connected flow (Stages I and II) and disconnected flow (Stage III) (Sawayama et al., 2021a).

attributable to percolation and is independent of fracture size, shear offset, fractal dimension, and fracture roughness. Below the percolation threshold (i.e., the partially disconnected regime), α = 1 indicates that tortuosity change remains nearly constant under normal stress (i.e., an aperture opening/closure). The impermeable faults may correspond to this regime, where the significance of the stagnant flow area may accelerate mineral precipitation or short-circuited flow paths. Above the percolation threshold, permeability is potentially enhanced by approximately 2.7 orders of magnitude given the same resistivity change. Although estimating the percolation transition is particularly crucial for practical application in the field, Sawayama et al. (2023b) discussed that the cross-plot of elastic wave velocity and electrical resistivity can identify the threshold.

It is important to note that the findings regarding these properties were only confirmed for single fractures. Considering matrix porosity and lithology, the slope will vary (Sawayama et al., 2024b; Sawayama and So, 2025). Moreover, fractures in natural settings exhibit greater complexity and intersect. Therefore, application of the present approach to a multiple fracture system is warranted. Given that the current approach utilized a three-dimensional calculation from the rock images, the established method can be readily applied to a multiple fracture system.

CONCLUSION

This study investigated the correlated changes in fracture permeability, resistivity, and elastic wave velocity of joints under increasing normal stress by coupling experimental data with digital fracture simulations. The principal findings are as follows:

- Changes in permeability and resistivity with stress are dependent on pore connectivity and exhibit reduced sensitivity to fracture roughness. The relationship between hydraulic and electrical properties remains independent of roughness, attributable to the roughness independence of fluid connectivity (as expressed by the hydraulic percolation threshold).

- The roughness dependency of elastic wave velocity arises from spatial distributions of contacting asperities as well as the roughness dependency of porosity.

- Fracture permeability, formation factor, and the relationship between them demonstrate scale independence with respect to the mean aperture. These behaviors originate from the tortuosity of the flow path.

- The scale-independent relationship between permeability and resistivity (k–F relationship) is governed by connectivity of flow paths.

- Normalized velocity exhibits a linear relationship with normalized permeability (k–V relationship) irrespective of fracture size.

These investigations of changes in hydraulic, electrical, and elastic properties of fractured rocks are significant for interpreting field geophysical data in studies of seismogenic zones and geothermal reservoirs. The proposed k–F and k–V relationships can be applied to various rock fractures with differing roughness and size. Although they necessitate further investigation under more realistic conditions, these relationships will be valuable for geophysical interpretation and fracture flow monitoring using remotely observed geophysical data.

ACKNOWLEDGEMENT

I would like to greatly thank my supervisors (Jun Nishijima, Yasuhiro Fujimitsu, Takeshi Tsuji), and other research collaborators (Tatsunori Ikeda, Fei Jiang, Takuya Ishibashi, Keigo Kitamura, and Osamu Nishizawa). I also appreciate the support from the JSRM (Japanese Society for Rock Mechanics) and the JSPS (Japan Society for the Promotion of Science).

SELECTED REFERENCES

Sawayama, K., Kitamura, K. and Fujimitsu, Y., 2018. Laboratory measurements on electric and elastic properties of fractured geothermal reservoir rocks under a simulated EGS condition, Geothermal Resources Council Transactions, 42, 2459–2475.

Sawayama, K., Kitamura, K., & Fujimitsu, Y., 2019. Effects of water saturation, fracture and salinity on electric and elastic properties of fractured geothermal rocks. Journal of Geothermal Research Society of Japan, 41, 53–59.

Sawayama, K., Ishibashi, T., Jiang, F., Tsuji, T., & Fujimitsu, Y., 2021a. Relating Hydraulic-Electrical-Elastic Properties of Natural Rock Fractures at Elevated Stress and Associated Transient Changes of Fracture Flow. Rock Mechanics and Rock Engineering, 54(5), 2145–2164.

Sawayama, K., Ishibashi, T., Jiang, F., Tsuji, T., Nishizawa, O., & Fujimitsu, Y., 2021b. Scale-independent relationship between permeability and resistivity in mated fractures with natural rough surfaces. Geothermics, 94, 102065.

Sawayama, K., Ikeda, T., Tsuji, T., Jiang, F., Nishizawa, O., & Fujimitsu, Y., 2022. Elastic wave velocity changes due to the fracture aperture and density, and direct correlation with permeability: an energetic approach to mated rock fractures. Journal of Geophysical Research: Solid Earth, 127(2), e2021JB022639.

Sawayama, K., Ishibashi, T., Jiang, F., Tsuji, T., 2023a. Relationship between permeability and resistivity of sheared rock fractures: the role of tortuosity and flow path percolation. Geophysical Research Letters, 50(20), e2023GL104418.

Sawayama, K., Ishibashi T., Jiang, F., and Tsuji, T., 2023b Rock physical modeling of sheared fractures: permeabilityresistivity-seismic velocity relationship explored via digital rock physics approach, 57th US Rock Mechanics/ Geomechanics Symposium, 0740.

Sawayama, K., 2024. Rock Physical Properties and Fracture Flow Behaviors: Towards Indirect Monitoring of Fractured Reservoirs, International Journal of the JSRM,20(1),240102.

Sawayama, K., Tsuji,T., and Shige, K., 2024a. Extracting Crucial Microstructures to Characterize the Elastic Wave Velocity and Resistivity of Berea Sandstone Using Convolutional Neural Networks. Geophysics 89(1), 117-126.

Sawayama, K., Ishibashi, T., Jiang, F., Tsuji, T., 2024b. Hydromechanical-electrical simulations of synthetic faults in two orthogonal directions with shear-induced anisotropy, Journal of Rock Mechanics and Geotechnical Engineering, 16(11), 4428—4439.

Sawayama, K., So, J., 2025. Electrical resistivity, permeability, and normal stiffness of fractured crystalline rocks: Simultaneous laboratory measurements subjected to hydromechanical loading. Advances in Geo-Energy Research, 16(1): 21-34.

JOHN HUDSON ROCK

ENGINEERING AWARD

Yufang Zhang | Beijing, China

RESEARCH AND APPLICATION OF ULTRA-HIGH AND LARGE ENERGY-GRADE FLEXIBLE PROTECTIVE STRUCTURE FOR HIGH POSITION ROCKFALLS ON THE CHENGDU-KUNMING RAILWAY

This application involves an innovative structure introduced for interception of high position rockfalls, including NPR net, anchor cable support pile, anchor cable slope beam, anchor cable ground beam, which meets the requirement of rockfall interception with high impact energy grades (15000kJ) and interception height (28m). It breaks through technical bottlenecks of the limited interception height (≤10m) and insufficient impact resistance energy capacity (≤10000kJ) of traditional flexible protective nets, which provides an effective technical solution for interception of high position rockfalls.

PROBLEM STATEMENT

The Yibo-Teke Bridge on Chengdu-Kunming Railway is surrounded by mountains on three sides, with steep terrain and fragmented rocks, (Fig.1). Potential falling rocks are distributed on the slope of which facade area is 47000 m2, with a maximum rockfall height of 450m. Large height difference, bounce height and impact energy of falling rocks greatly threaten the railway’s operation safety.

It is extremely difficult and economically expensive to carry out in-situ reinforcement of scattered and widely distributed rocks. Therefore, it is imperative to design new structure suitable for interception of high position falling rocks.

Fig. 1 - A panoramic map of dangerous rocks distribution

STRUCTURAL SYSTEM

The structural system includes NPR net, anchor cable support pile, anchor cable slope beam, anchor cable ground beam, forming a ‘Net-Pile-Anchor’ structural system (Fig.2).

NPR net is made of horizontal and vertical braided steel strands with a Negative Poisson's Ratio effect. Anchor cable support pile is composed of a pile and anchor cables, which provides impact reverse counterbalance forces. Anchor cable slope beam uses anchor cables to stabilize the NPR net in the mountain and provide pulling effects for the horizontal NPR steel strands. Anchor cable ground beam provides reaction forces for NPR anchor cable support piles.

ENERGY DISSIPATION AND STRUCTURAL CALCULATION

The method for structural design and calculation has been proposed, as follows:

Firstly, calculate the impact resistance energy.

The innovative flexible protective structure uses NPR net to bear impact energy of falling rocks. The NPR material constitutive model (Fig.3) and structural calculation diagram (Fig.4) are proposed.

Single NPR steel strand Elastic Stage energy absorption:

Single NPR steel strand Plastic Stage energy absorption:

Single bundles NPR steel strand Elastoplastic Stage energy absorption:

In the formula, Welastic is work done by NPR anchor cable in elastic stage. Wplastic is work done by NPR anchor cable in plastic stage. W prestress is work done by NPR anchor cable in prestress stage. Fmax is constant force of NPR anchor cable (constant resistance). L is length of NPR anchor cable. ∆ s is elongation rate of NPR anchor cable when reaching yield state. ∆max is the ultimate elongation of NPR anchor cable when reaching broken state.

Fig. 2 - Schematic diagram of the structural system

Fig. 3 - NPR material constitutive model

Fig. 4 - Calculation diagram

Secondly, calculate the design force on the anchor cable support pile.

The NPR net transmits the impact load to anchor cable support piles. The force mode of anchor cable support pile (Fig.5) and force calculation diagram (Fig.6) are proposed. Following assumptions are proposed: First, assume rockfall impact load as a concentrated force and set it 1.6m from the pile top by considering the most unfavorable position of rockfall impact loads. Second, each anchor cable is elastically constrained. Third, foundation deformation and force constraints in the embedded section of the support pile conform to Winkler assumption.

NUMERICAL SIMULATION

A numerical model (Fig.7) was established to simulate the rockfall impaction with an energy of 15,000kJ. Plastic strain and displacement of the net were analyzed (Fig.8).

When calculation time T=0.299s, the rockfall velocity is 0. The corresponding maximum plastic strain is 0.92. The rockfall impact energy is absorbed through plastic deformation. The maximum deformation of the net along the impact direction is 5.5m which is less than the safety distance of 8m. Thus, it can be considered the net can successfully complete rockfall interception of 15000kJ.

Fig. 5 - Force mode of anchor cable support pile

Fig. 6 - Force calculation diagram

The maximum horizontal force bearing capacity of a single NPR steel strand:

Design horizontal force on anchor cable support pile when considering a bundle of n NPR steel strands with a safety factor k:

Fig. 7 - Numerical Model

Fig. 8 - Numerical simulation

(b) Displacement

(a) Plastic strain

ON-SITE CONSTRUCTION

The on-site construction of the ultra-high and large energygrade flexible protective structure has overcome the difficulties of high-altitude operations during construction, proposing a complete set of high-altitude operation construction technologies (Fig.9) to complete high-altitude mesh weaving. The completed ultra-high and large energy-grade flexible protective structure is shown in Fig.10.

COMPARISON OF TECHNOLOGICAL ADVANCEMENT

Compared with traditional passive protective nets, the impact resistance energy of the innovative structure is increased from 10,000kJ to 15,000kJ, and the interception height is increased from 10m to 28m.

Fig. 9 - On-site high-altitude operation construction technologies

Fig. 10 - The completed innovative structure on-site

(a) high-altitude mesh weaving

(b) fastening cross buckles

YOUNG ROCK

ENGINEER AWARD

Gabriel Walton | Colorado School of Mines, USA

This paper is intended to highlight key contributions made by the recipient of the 2024 ISRM Young Rock Engineer Award and his research group members at the Colorado School of Mines. Among the various contributions made, four specific areas of practical contributions to rock engineering are highlighted: brittle intact rock damage and implications for mine pillars, advances in bonded block modeling, tools for flat-roofed excavation support design, and rockfall hazard management through remote-sensing-based monitoring.

BRITTLE INTACT ROCK DAMAGE AND IMPLICATIONS FOR MINE PILLARS

Seminal contributions by Martin & Chandler (1994), Martin (1997), and Diederichs (2003) developed a new paradigm for understanding and simulating brittle damage in intact rock under high stresses. This ultimately led to the development of the cohesion-weakening-friction-strengthening (CWFS) strength parameterization approach (Hajiabdolmajid et al., 2002), which has been consistently demonstrated to be capable of reproducing observed geometries of spalling fracture development around excavations under high stress.

Despite reproducing fracture zone geometries, continuum models using CWFS were not reliably able to reproduce observed ground displacement trends associated with spalling. This was largely due to the manner in which dilatancy (inelastic volumetric expansion) was simulated, typically using a constant dilation angle based on rules of thumb. Building off prior laboratory-based studies, Walton & Diederichs (2015a) developed a dilation angle model considering the effects of confining stress and damage accumulation. Walton (2014) demonstrated that the use of this model with laboratoryderived parameters in conjunction with a CWFS model could reproduce not only the geometry of stress-induced fracturing around excavations in brittle rock, but also the displacement profile of the rock around the excavation. For practical purposes when a more sophisticated dilation angle model could not be used, Walton & Diederichs (2015b) developed an equation for selecting a constant dilation angle for simplified simulation purposes:

where ψ is the dilation angle, ϕp is the peak friction angle, σ1 and σ3 are the major and minor principal stresses around an excavation, respectively, and the “In-Situ Strength” is the peak strength of the rock (or rockmass) around the excavation.

When using the CWFS model, some parameters could be determined directly from laboratory data, but overall, parameter determination was still largely a calibration exercise; this calibration process is subject to substantial non-uniqueness, particularly for calibrations performed solely considering fracture zone geometry. To provide practitioners with a starting point, knowledge gained from extensive CWFS modeling of brittle rock damage around excavations was documented as a series of parameter selection guidelines (Walton, 2019).

One limitation of the CWFS model is that it fails to account for potential behavior that can develop in highly confined pillar cores (or other higher confining stress environments) that corresponds to a brittle shear damage mechanism more than a macroscopic extensional fracturing (spalling) mechanism. This mechanistic transition is captured by the “S-shaped” strength envelope, which was conceived by Diederichs (2007) and formalized by Kaiser et al. (2011); this envelope was simply intended to represent the overall peak strength at any given confinement without consideration of pre-peak damage evolution. To address this limitation, Sinha & Walton (2018) developed a modeling approach that reproduced both progressive damage development and the S-shaped peak strength at a wide range of confinements. This ultimately prompted a re-examination of the Lunder & Pakalnis (1997) hard rock pillar strength database that led to a recognition of a non-linear dependence of pillar strength on UCS; accordingly, pillars in highly brittle rocks with very high UCS may have their strength overestimated by classical pillar strength equations (Figure 1) (Walton & Sinha, 2021).

More recently, Chaurasia et al. (2024a) completed a unique large-scale (0.5 m x 0.5 m cross-section) pillar analog testing program that incorporated instrumented full-scale support elements (Figure 2). The results of these experiments confirmed earlier numerical findings regarding the lack of any appreciable influence of rockbolt support on pillar peak strength but the existence of a notable influence on residual strength for massive pillars (Sinha & Walton, 2021a). Additionally, the substantial effect of areal support (e.g. wire mesh) in increasing residual strength was quantified.

ADVANCES IN BONDED BLOCK MODELING

Because of limitations of continuum models regarding the simulation of large-scale bulking processes and certain aspects of rock-support-interaction, discontinuum approaches for simulation of rock fracture under high compressive stresses have become increasingly popular over the past two decades. One such approach is the Bonded Block Modeling (BBM) approach, where blocks represent “unbreakable” (e.g. continuum) elements within the model and the boundaries between blocks (“contacts”) represent potential fracture pathways. Many BBM studies have focused on the simulation of laboratory compression tests, demonstrating fundamental capabilities of the model approach and evaluating the influence of specific modeling decisions (e.g. the use of triangular blocks versus Voronoi-tessellated blocks). At the laboratory scale, Sinha & Walton (2020) provided a comprehensive study regarding the roles of explicit representation of grain-scale heterogeneity and grain inelasticity in allowing for simulation of specific aspects of rock behavior as observed in the laboratory. Notably, heterogeneity in grain stiffness was found to be critical for replicating of pre-peak stress thresholds (crack initiation, crack damage) under confined loading conditions, and grain inelasticity was found to be critical for replicating realistic post-peak specimen behavior. Contreras et al. (2023) compared BBM models using a deterministic (specimenmapped) grain geometry to those using a simplified (stateof-practice) Voronoi grain geometries (Figure 3) and demonstrated they performed equally well in replicating observed specimen strength.

3 (a) - granite specimen and (b-e) simulated grain geometries representing increasing degrees of simplification relative to the mapped geometry shown in (b) (after Contreras et al., 2023).

At the field scale, many studies have presented sensitivity analyses evaluating the relative influences of loading conditions, support, or material properties in the contexts of specific case studies. A relatively limited number of studies with quantitative field-scale calibration, particularly to excavation deformation data, have been conducted. Sinha & Walton (2021b) demonstrated that a properly calibrated field-scale BBM could indeed replicate observed trends in

Fig. 1 - Comparison of improved empirical pillar strength model predictions with that of the Lunder & Pakalnis (1997) model (from Walton & Sinha, 2021).

Fig. 2 - A large-scale compression test on a cubic specimen with installed support (after Chaurasia et al., 2024).

W/H Ratio

K-Feldspar Plagioclase Quartz Biotite

Fig.

ground deformation. Perhaps more significantly, a case study based on the work of Colwell (2006) was used to demonstrate the predictive capabilities of such models when assessing the influence of rock reinforcement on ground deformation: a model was calibrated to data for a pillar with one support condition and then was shown to accurately predict deformation of a more heavily supported pillar without further calibration (Figure 4) (Sinha & Walton, 2021c). Based on experience with these and other case studies, the authors concluded that consideration of inelastic deformation within blocks is critical to the ability of the models to simulate macroscopic ground deformation trends (Walton & Sinha, 2020).

TOOLS FOR FLAT-ROOFED EXCAVATION DESIGN

Passive rockbolts represent one of the main ground support elements used in the construction of excavations, and are increasingly used as part of permanent support systems in civil and mining applications. Standard passive rockbolt designs for flat-roofed excavations involve the installation of evenly spaced vertical rockbolts into the excavation roof with typical pattern spacings ranging from 1.0 m to 2.5 m depending on excavation span and rock mass quality.

This conventional design ignores the difference in deformation mechanism at the mid-span and abutments (tension and shear, respectively) and the potential role of mitigating shear deformation near the abutments in minimizing midspan deflection and block loosening. To evaluate the potential relative performance of different support geometries (using a consistent number of rockbolts) developed with these considerations in mind, Walton et al. (2019) conducted a numerical parametric study considering different geological and geotechnical conditions in laminated ground. In a comparison of eight different support geometries (Figure 5), it was found that while the “standard” approach of using evenly spaced vertical rockbolts tended to lead to roof deformations only slightly in excess of the optimal support geometry in any given scenario, a pattern using angled outer bolts (to promote more rapid mobilization against abutment shear) and an uneven bolt spacing (tighter spacing of central vertical bolts and wider spacing between vertical and inclined bolts) tended to perform better overall.

Fig. 4 - Displacement contours for (a) unsupported coal, (b) 2 bolt condition (calibration case) and (c) 4 bolt condition (prediction case; fieldmeasured displacement = 23 mm) (after Sinha & Walton, 2021c).

To analyze roof stability for flat-roofed excavations, analytical approaches based on the Voussoir beam analog have been proposed. Such analytical solutions, however, are not able to accurately account for the influence of installed passive rockbolt reinforcement. To overcome this limitation, Abousleiman et al. (2021) numerically modeled a large number of excavation scenarios and developed an adjustment that could be applied to analytical solution input parameters to reproduce expected results for bolted roof scenarios. Specifically, they found that multi-layered roofs with typical rockbolt densities behaved neither like a single beam with the thickness of the bolted interval, nor a single beam with the thickness of an individual rock layer, but rather exhibited an intermediate behavior (Figure 6). Accordingly, the Diederichs & Kaiser (1999) analytical solution can be used to simulate bolted roof deformation using the bolted interval thickness as the beam thickness and a corresponding reduced rockmass stiffness determined per the method proposed by Abousleiman et al. (2021). This approach has since been applied in multiple case studies and found to produce accurate predictive results (Abousleiman et al., 2023; Terron-Almenara et al., 2024).

Fig. 5 - Tested support geometries; geometry #4 was identified as best-performing in a parametric study (Walton et al., 2019).

Fig. 6 - Comparison of horizontal stress (left) and vertical displacement (right) results of multiple beam geometries ranging from a single, unbolted, 1 m thick beam (top) to a single, unbolted, 0.5 m thick beam (bottom), and variations between these end-member cases (Abousleiman et al., 2021).

ROCKFALL HAZARD MANAGEMENT THROUGH REMOTE-SENSING-BASED MONITORING

Point-cloud-based remote sensing monitoring techniques (lidar, photogrammetry) have become increasingly common in rockfall monitoring applications over the past decade. To overcome cost limitations associated with repeat lidar monitoring and to avoid temporal resolution limitations associated with the need to repeatedly travel to the field for data collection, Kromer et al. (2019) developed a fixed photogrammetry monitoring solution (Figure 7) and demonstrated its applicability to rockfall monitoring. This system allows for high temporal resolution data collection while being inherently flexible in its design to allow for system optimization for individual use cases. This technology has since been applied by the research group for the development of rockfall databases and study of associated processes and triggers at multiple different sites (Walton et al., 2023a; Butcher et al., 2023; Hollander et al., 2024).

In addition to developing understanding of underlying physical processes, lidar and photogrammetry data have been used to inform hazard quantification and management. For example, Weidner & Walton (2021) evaluated rockfall trends prior to and following the completion of a slope hazard mitigation program involving scaling and polyurethane resin injection and proposed hypotheses to explain the trends observed. Phillips (2024) compiled data from multiple slopes around Colorado and from the worldwide literature to evaluate key geological factors that can be used to inform preliminary hazard assessment in the absence of existing rockfall databases. Walton et al. (2023b) documented a case study where slope monitoring had successfully identified a large accelerating block and allowed for transportation authorities to effectively mitigate the hazard (Figure 8).

REFERENCES

Abousleiman, R., Sinha, S., & Walton, G. (2021). Expanding application of the voussoir beam analog to horizontally bedded and passively bolted flat-roof excavations using the discrete element method. International Journal of Rock Mechanics and Mining Sciences, 148, 104919.

Abousleiman, R., Sinha, S., & Walton, G. (2023). Analysis of the historic bondi pumping chamber case study using the adjusted voussoir beam analog. Rock Mechanics and Rock Engineering, 56(9), 6357-6374.

Butcher, B., Walton, G., Kromer, R., Gonzales, E., Ticona, J., & Minaya, A. (2023). High-Temporal-Resolution Rock Slope Monitoring Using Terrestrial Structure-from-Motion Photogrammetry in an Application with Spatial Resolution Limitations. Remote Sensing, 16(1), 66.

Chaurasia, A., Walton, G., Sinha, S., Batchler, T. J., Moore, K., Vlachopoulos, N., & Forbes, B. (2024). Large-scale laboratory investigation of pillar-support interaction. Journal of Rock Mechanics and Geotechnical Engineering. Colwell, M. G. (2006). A Study of the Mechanics of Coal Mine Rib Deformation and Rib Support as a basis for Engineering Design. Ph.D. Thesis. University of Queensland, Australia.

Fig. 7 - Fixed photogrammetry system data processing pipeline from data collection to production of change detection results (Kromer et al., 2019).

Fig. 8 - Photo showing the location of the identified unstable block with a zoomed view including an overlay of the block after support installation; a time-series (courtesy L. Weidner) illustrates the observed trend in average block displacement and the effective stop of block movement following the installation of support, as indicated by the dashed line (after Walton et al., 2023b).

Inga, C. E. C., Sinha, S., Walton, G., & Holley, E. (2023). Modeling Brazilian tensile strength tests on a brittle rock using deterministic, semi-deterministic, and Voronoi bonded block models. Rock Mechanics and Rock Engineering, 56(7), 5293-5313.

Diederichs, M. S. (2003). Manuel rocha medal recipient rock fracture and collapse under low confinement conditions. Rock Mechanics and Rock Engineering, 36, 339-381.

Diederichs, M. S. (2007). The 2003 Canadian Geotechnical Colloquium: Mechanistic interpretation and practical application of damage and spalling prediction criteria for deep tunnelling. Canadian Geotechnical Journal, 44(9), 1082-1116.

Hajiabdolmajid, V., Kaiser, P.K., & Martin, C.D. (2002). Modelling brittle failure of rock. International Journal of Rock Mechanics and Mining Sciences, 39(6), 731-741.

Hollander, J. A., Walton, G., & Kromer, R. (2024). Development of a Photogrammetric Rockfall Database and Analysis of Trends at a Rock Slope Along I-70W, West of Idaho Springs, CO. In ARMA US Rock Mechanics/Geomechanics Symposium (p. D022S023R012). ARMA.

Kaiser, P. K., Kim, B., Bewick, R. P., & Valley, B. (2011). Rock mass strength at depth and implications for pillar design. Mining Technology, 120(3), 170-179.

Kromer, R., Walton, G., Gray, B., Lato, M., & Group, R. (2019). Development and optimization of an automated fixed-location time lapse photogrammetric rock slope monitoring system. Remote Sensing, 11(16), 1890.

Lunder, P. J., & Pakalnis, R. C. (1997). Determination of the strength of hard-rock mine pillars. CIM bulletin, 90(1013), 51-55.

Martin, C. D., & Chandler, N. A. (1994). The progressive fracture of Lac du Bonnet granite. In International journal of rock mechanics and mining sciences & geomechanics abstracts (Vol. 31, No. 6, pp. 643-659). Pergamon.

Martin, C. D. (1997). Seventeenth Canadian geotechnical colloquium: the effect of cohesion loss and stress path on brittle rock strength. Canadian Geotechnical Journal, 34(5), 698-725.

Phillips, C. (2024). Quantifying causes and variability of rockfall activity: comparison of rock slopes monitored using terrestrial remote sensing. M.Sc. Thesis. Colorado School of Mines, United States.

Sinha, S., & Walton, G. (2018). A progressive S-shaped yield criterion and its application to rock pillar behavior. International Journal of Rock Mechanics and Mining Sciences, 105, 98-109.

Sinha, S., & Walton, G. (2020). A study on Bonded Block Model (BBM) complexity for simulation of laboratory-scale stressstrain behavior in granitic rocks. Computers and Geotechnics, 118, 103363.

Sinha, S., & Walton, G. (2021a). Investigation of pillar damage mechanisms and rock-support interaction using Bonded Block Models. International Journal of Rock Mechanics and Mining Sciences, 138, 104652.

Sinha, S., & Walton, G. (2021b). Integration of three-dimensional continuum model and two-dimensional bonded block model for studying the damage process in a granite pillar at the Creighton Mine, Sudbury, Canada. Journal of Rock Mechanics and Geotechnical Engineering, 13(2), 275-288.

Sinha, S., & Walton, G. (2021c). Modeling the behavior of a coal pillar rib using bonded block models with emphasis on groundsupport interaction. International Journal of Rock Mechanics and Mining Sciences, 148, 104965.

Terron-Almenara, J., Skretting, E., & Holter, K. G. (2024). Design of Rock Support in Low Overburden and Hard Rock Conditions with the use of Rock Mass Classification Systems and Numerical Analyses: a Study Based on the Construction of the Hestnes Railway Tunnel, Norway. Rock Mechanics and Rock Engineering, 1-26.

Walton, G. (2014). Improving continuum models for excavations in rockmasses under high stress through an enhanced understanding of post-yield dilatancy. Ph.D. Thesis. Queen’s University, Canada.

Walton, G. (2019). Initial guidelines for the selection of input parameters for cohesion-weakening-friction-strengthening (CWFS) analysis of excavations in brittle rock. Tunnelling and Underground Space Technology, 84, 189-200.

Walton, G., & Diederichs, M. S. (2015a). A new model for the dilation of brittle rocks based on laboratory compression test data with separate treatment of dilatancy mobilization and decay. Geotechnical and Geological Engineering, 33, 661-679.

Walton, G., & Diederichs, M. S. (2015b). Dilation and postpeak behaviour inputs for practical engineering analysis. Geotechnical and Geological Engineering, 33, 15-34

Walton, G., & Sinha, S. (2020). Advances in bonded block modeling. Proceedings of Bergmekanikdagen, Swedish Rock Engineering Association, Sweden.

Walton, G., & Sinha, S. (2021). Improved empirical hard rock pillar strength predictions using unconfined compressive strength as a proxy for brittleness. International Journal of Rock Mechanics and Mining Sciences, 148, 104934.

Walton, G., Diederichs, M., Punkkinen, A., & Whitmore, J. (2016). Back analysis of a pillar monitoring experiment at 2.4 km depth in the Sudbury Basin, Canada. International Journal of Rock Mechanics and Mining Sciences, 85, 33-51.

Walton, G., Abousleiman, R., Sinha, S., & Crockford, A. (2019). A Numerical Study on the Optimization of Rockbolt Support for Flat-Roofed Excavations in Laminated Ground. In 14th ISRM Congress, Foz do Iguaçu, Brazil, September 2019.

Walton, G., Christiansen, C., Kromer, R., & Silaev, A. (2023). Evaluation of rockfall trends at a sedimentary rock cut near Manitou Springs, Colorado, using daily photogrammetric monitoring: Evaluation of rockfall trends at a sedimentary rock cut. Landslides, 20(12), 2657-2674.

Walton, G., Malsam, A., Oester Mapes, N., & Arpin, B. (2023). Forecasting and mitigating rockfall based on lidar monitoring: a case study from Colorado. Transportation research record, 2677(10), 863-870.

Weidner, L., & Walton, G. (2021). Monitoring the effects of slope hazard mitigation and weather on rockfall along a Colorado highway using terrestrial laser scanning. Remote Sensing, 13(22), 4584.

SCIENCE

ACHIEVEMENT AWARD

Pinnaduwa H.S.W. Kulatilake | Tucson, USA

RESEARCH AND APPLICATION OF ULTRA-HIGH AND LARGE CURRENT STATUS ON ROCK MASS STRENGTH AND RECENTLY DEVELOPED NEW THREE-DIMENSIONAL (3-D) ROCK MASS STRENGTH CRITERIA

The presence of complex discontinuity patterns, the inherent statistical nature of their geometrical parameters, the variabilities and uncertainties involved in the estimation of the discontinuity geometrical and geo-mechanical properties, and the complex three-dimensional (3-D) in-situ stress make accurate predictions of rock mass strength a very difficult task. It has been a great challenge for the rock mechanics and rock engineering profession to develop a rock mass strength criterion in 3-D that incorporates the effect of the minor and intermediate principal stresses and captures the scale-dependent and anisotropic properties resulting from the discontinuity geometry parameters such as the number of discontinuity sets, 3-D discontinuity intensity and the distributions of the discontinuity orientation and size. The paper provides a critical review of the current status of rock mass strength criteria and presents recently developed, most advanced 3-D rock mass strength criteria which incorporate the effect of the minor and intermediate principal stresses and capture the scale-dependent and anisotropic behaviour.

1. INTRODUCTION

Most naturally occurring discontinuous rock masses comprise intact rock interspaced with different types of discontinuities. Fissures, fractures, joints, faults, bedding planes, folds, shear zones, and dykes are different types of discontinuities that exist in rock masses. Henceforth, the minor discontinuities are referred to as either “joints” or “fractures” in this paper. Due to the presence of discontinuities, the geomechanical response of discontinuous rock masses can be highly complicated under complex geology and in-situ stress systems. Therefore, civil and mining engineers face many difficulties in tackling design and construction tasks associated with geotechnical systems that are in or on discontinuous rock masses. Such geotechnical systems cover a wide range of surface and underground excavations made for ore extraction, tunnels for hydropower and transport, dams, deep foundations, natural and manmade rock slopes, and underground repositories for oil, gas, and hazardous waste. In dealing with these rock engineering projects rock mass stability is the main concern for the engineers. To arrive at safe and economical designs, it is very important to have a good understanding of the rock mass strength. Rock mass strength depends on the (a) lithology, (b) discontinuity geometry network including the number of discontinuity sets, their intensity, the spatial distribution of orientation, size, and spacing, (c) geo-mechanical properties of the discontinuities including roughness, strength, and deformation of asperities and filling material, (d) geomechanical properties of the intact rock, (e) in-situ stress system, (f) size and shape of the rock mass, (g) loading/ unloading stress path, (h) loading rate, (i) pore pressure in the rock mass and (j) environmental conditions (such as the temperature, humidity etc.) of the rock mass. The presence of

complicated fracture networks, the inherent statistical nature of their geometrical parameters, and the variabilities and uncertainties involved in the estimation of their geometrical and geo-mechanical properties and complicated in-situ stress make accurate prediction of rock mass strength a very difficult, challenging task (Kulatilake 1985; Kulatilake et al. 1993). On the other hand, unfortunately, understanding the mechanical behavior of rock masses is crucial in designing safe and economical structures in or on rock masses.

Representative elementary volume (REV) is a definition proposed by Hill (1963) in the theory of composite materials. REV is the threshold volume beyond which the considered property value will approach an almost constant value and represent the equivalent behavior of the whole (Kulatilake et al. 1993). Based on the rock fracture data available from a dam site in China, Wu and Kulatilake (2012) investigated the REV size for the fracture system and mechanical properties of the rock mass. They found that the REV size was around 8-10 times the mean discontinuity size of the rock mass to represent the fracture system and mechanical properties of the rock mass. To estimate the mechanical properties of the REV size, they performed numerical simulations to obtain rock mass strength and deformability parameter values in every 45° direction in 3-D. Their numerical results indicate that the strength and deformability of rock masses are highly influenced by the pre-existing fracture system of the rock masses and thus show a very significant scale effect and anisotropic behavior. It has been a great challenge for the rock mechanics and rock engineering profession to develop a rock mass strength criterion in 3-D which incorporates the effect of important fracture geometry parameters and intermediate principal stress

and to capture the scale effects and anisotropic properties of jointed rock masses. This paper aims at first providing the current status of rock mass strength and then reporting on the recently developed new 3-D rock mass strength criteria which incorporate the influence of pre-existing fracture networks and confining stresses and show the capability of capturing the scale effect and anisotropic behavior of rock masses.

2. LITERATURE REVIEW ON ESTIMATION OF ROCK MASS STRENGTH USING PHYSICAL, EMPIRICAL AND NUMERICAL MODELING

2.1 Laboratory and field investigations to estimate rock mass strength

The direct way to estimate rock mass strength is through laboratory or in-situ tests. In the laboratory scale, commonly used samples are cylindrical samples with a diameter of 50 mm. Although some testing facilities allow larger sizes of rock samples, such as 110 mm, 160 mm, or even larger sidedimension cubic rock blocks, the limited sample size can only include a few statistically distributed fractures. Therefore, the test results always show a high variability and scale dependence. Laboratory results obtained from small-sized specimens that include only micro-joints are very different from the results obtained from large-scale blocks because the laboratory samples cannot accommodate the whole spectrum of different-size discontinuity networks which is present in the field. To obtain realistic results for jointed rock mass mechanical properties, many large volumes of rock of different sizes having several different known joint configurations should be tested at significant stress levels under different stress paths. Such an experimental program is almost impossible to carry out in the laboratory. With in-situ tests, such an experimental program would be very difficult, time-consuming, and expensive. Results of laboratory model studies on rock-like materials (Brown 1970; Einstein and Hirschfeld, 1973; Chappel 1974; Heuze, 1980; Yang et al. 1998; Kulatilake et al., 2001a, 2001b and 2006) have shown that many different failure modes are possible with jointed rock and that the internal distribution of stresses and strains within a jointed rock mass can be highly complex. Even though these jointed blocks included a significant number of joints, all the included joints were persistent. Only a few experimental studies have been done using a significant number of nonpersistent joints (Prudencio and Van Sint Jan 2007; Mughieda et al. 2008; Chen et al., 2011 and 2012; Fan et al. 2015). Although the above research reveals the influence of the fractures on the rock mass behaviors, the fracture networks involved are far more simplified than the naturally occurring rock masses. Concerning the in-situ tests, Bieniawski and Van Heerden (1975), and Heuze (1980) have reviewed the work done before their publications on scale effects on rock mass strength. The reported results from these investigations clearly show that the rock mass strength reduces with size and approaches a constant value after the rock mass size has reached a certain size known as the REV size. It is important to note that the relations developed from in-situ tests in the above-stated studies primarily depend on the discontinuity network of the tested rock masses. However, unfortunately, in these early investigations, no attempt had been made to map the discontinuity network before subjecting the rock mass to

mechanical behavior testing. Therefore, the reported relations are highly site-dependent and have qualitative value only. The reader is referred to Kulatilake (2021) for a state-of-theart report on the use of laboratory and field physical tests in estimating rock mass strength.

2.2 Empirical rock mass strength criteria

One indirect way to estimate the rock mass strength is through empirical equations. Several empirical rock mass strength criteria have been suggested in the literature. The oldest one is the Mohr-Coulomb criterion. The Mohr-Coulomb criterion provides a linear prediction of the rock mass strength without consideration of the intermediate principal stress, σ2. On the other hand, the experimental test results indicate that the rock mass strength exhibits non-linear properties and dependence on σ2. This criterion over-predicts the rock mass strength at higher confining stress levels and provides an unreasonable tensile strength value. Therefore, for practical use, this criterion is always combined with a tension cut-off. In addition to the above shortcomings, no guidelines are available to relate the two strength parameters given in the MohrCoulomb criterion to discontinuity geometry and discontinuity mechanical parameters. It has been used in practice mainly because of its simplicity.

Most of the rest of the rock mass strength criteria are used with a certain rock mass classification system. Edelbro (2006) reviewed twenty-one different rock mass classification systems developed by different researchers in the 20th century. Each system is applied to a specific area, such as tunneling, rock support, mining, or rock slopes. All these rock mass classification systems only provide a rough evaluation for the rock mass quality with the following shortcomings: (a) all the parameters used in these rock mass classification systems are scalar based, which is not adequate for the description of the anisotropic behavior of the rock masses; (b) the most important geometric feature of discontinuities, the joint orientation is not explicitly used in all the systems, even though some systems provide an adjustment for joint orientation; (c) Joint size, which makes mechanical properties of rock masses scale-dependent, is not explicitly included; (d) rock quality designation (RQD) used in some rock mass classification systems are highly orientation and location dependent; (e) RQD can be considered as one-dimensional joint frequency; in the rock mass classification systems which include both RQD and joint spacing, the same factor is double counted.

Hoek and Brown rock mass strength criterion (Hoek and Brown 1980) was introduced in 1980 as an attempt to provide input data for the analyses required for the design of underground excavations in hard rock. It is an empirical criterion developed through trial and error curve fitting of different parabolic functions to standard triaxial test data. The choice of a parabolic function seems to have originated from one part of the equation given for Griffith’s crack theory (Griffith 1920 and 1924). The empirical parameters of the criterion were first developed for intact rock and then those parameter values were reduced by linking them to Bieniawski’s (1976) Rock Mass Rating (RMR) classification system. Since 1980 the criterion has been updated several times (Hoek et al. 1992; Hoek and Brown 1997; Hoek et al. 2002; Hoek and Brown 2019). The most current one seems to be the Generalized

Hoek-Brown criterion. The empirical parameters of this criterion were related to the Geological Strength Index (GSI) introduced by Hoek et al. (1992). GSI is determined based on the structure of the rock blocks and the surface conditions of the joints. The number of joint sets and fracturing level are considered in evaluating the structure of the rock blocks. Roughness/smoothness, degree of weathering, degree of alteration, and presence and type of filling are considered in evaluating the surface conditions of the joints. Cai et al. (2004) modified the descriptive term “the structure of the rock blocks” to “quantitative block volume” and the descriptive term “the joint surface condition” to “quantitative joint condition factor” in estimating the GSI value for a rock mass. Being a nonlinear strength criterion, the Hoek-Brown criterion provides more reasonable predictions compared to that of the MohrCoulomb criterion. In addition, a lot of information is available to estimate the empirical parameters given in the Hoek-Brown criterion. Therefore, in practice, the Hoek-Brown criterion has been used more often than the Mohr-Coulomb criterion. However, the Hoek-Brown criterion does not incorporate the effect of σ2 and cannot capture the anisotropy, and scale effects behaviors of a rock mass. Due to the assumption of isotropic behavior of the rock mass, the Hoek and Brown criterion can only be considered for highly fractured rock masses having highly randomly oriented fracture systems. For further details on this criterion, the reader is referred to Kulatilake (2021).

Some investigators extended this Hoek-Brown criterion to 3-D versions to incorporate the influence of σ2 (Pan and Hudson 1988; Priest 2005; Zhang and Zhu 2008; Melkoumian et al. 2009; Zhang et al. 2013). For details of these 3-D developments and the shortcomings of the models, the reader is referred to He et al. (2017). All these criteria inherit the isotropic behavior and do not include joint orientation and joint size explicitly to capture the anisotropy and scale effects of rock mass strength.

Yudhbir et al. (1983), Sheorey et al. (1989), and Ramamurthy (2001) proposed different forms of σ1=f(σ3) equations to estimate the rock mass strengths. Out of the three criteria, only the Ramamurthy criterion includes factors considering the effect of the orientation of a sliding joint or joint set; however, multiple joint sets are not considered in this criterion. The joint orientation is not explicitly considered in all three criteria. It is important to note that all three criteria cannot capture the influence of intermediate principal stress, scale effect, and anisotropic rock mass behaviors. For details on these three criteria, the reader is referred to Kulatilake (2017).

Kulatilake et al. (2006) performed uniaxial and biaxial compression tests on Glastone model material intact prismatic samples and jointed blocks of size 35.6 x 17.8 x 2.5 cm. Based on the test results of intact samples a new intact rock failure criterion in 3-D was proposed. Both persistent and impersistent smooth joint configurations were included in producing jointed model material blocks. The fracture tensor component (Kulatilake et al. 1993) was used to quantify the directional effect of the joint geometry, including the number of fracture sets, fracture density, and probability distributions for the size and orientation of the fracture sets. The strength results obtained for the jointed Glastone blocks and intact Glastone blocks were used along with PFC3D modeling in

developing a rock mass failure criterion for biaxial loading conditions. This criterion relates the rock mass strength to the fracture tensor component and intermediate principal stress. For further details on these criteria, the reader is referred to Kulatilake (2021). A recently developed coal mass strength criterion extending Kulatilake et al.’s (2006) criterion to three dimensions is given in a later section of this paper.

2.3 Rock mass strength estimation through analytical methods

The second indirect approach to studying rock mass strength behavior is through the analytical decomposition technique. Jennings (1970) expressed the combined strength of joint and rock bridges by simple linear weighing of the strength contributed by each fraction of material. Amadei (1988), Bekaert and Maghous (1996), and Pouya and Ghoreychi (2001) also have used analytical approaches by selecting intact rock and rock discontinuity strength criteria and applying simplified methods to combine them, to develop rock mass strength criteria. In all these derivations, simplified fracture systems have been used ignoring the interactions between the intact rock and joints. That means those methods disregarded the possibility of progressive failure. Therefore, these methods are rarely applicable in dealing with field rock masses, which contain highly complicated fracture systems and behave in very complicated ways compared to the assumed simplified models.

2.4 Rock mass strength estimation through numerical modeling

The other indirect approach available to estimate rock mass strength is the numerical decomposition technique. The following three types of numerical modeling have been used to model rock mass strength: a) Finite Element Modeling (FEM); b) Particle Flow Modeling through PFC2D or PFC3D (Itasca 2003; Ivars et al. 2011) and c) Distinct Element Modeling through UDEC and 3DEC (Itasca 2008). Since the finite element method is based on continuum mechanics, simulation of large displacements and large rotations is difficult with the method, even though they may occur in jointed rock masses. The distinct element method introduced by Cundall [1971] and further developed by Lemos et al. [1985], Cundall [1988], and Hart et al. [1988] is a powerful technique to perform stress analyses in discontinuous blocky rock masses. In this method, the rock mass is modeled as an assemblage of rigid or deformable blocks, and discontinuities are considered as distinct boundary interactions between these blocks; joint behavior is prescribed for these interactions. The distinct element algorithm includes not only continuum theory representation for the blocks but also force-displacement laws which specify forces between blocks, and a motion law which specifies the motion of each block due to unbalanced forces acting on the block. By taking into account the interaction of intact blocks and joints, the distinct element method can effectively calculate the mechanical behavior of block systems under different stress and displacement boundary conditions. This method employs an explicit solution procedure. An advantage of the explicit method is that because matrices are never formed, large displacements, rotations, and complex constitutive behavior for both the intact material and joints are possible with no additional computing effort. For details on the distinct element theory, the readers are referred to the

publications mentioned in this paragraph. The PFC3D allows one to study the mechanical interaction behavior between intact rock and joints incorporating a significant number of joints without making unrealistic assumptions about the surrounding medium around each joint. In addition, it allows failure through both the intact rock and joints under both tensile and shear modes leading to progressive failure which usually occurs in jointed blocks having non-persistent joints. Therefore, both 3DEC and PFC3D are suitable for estimating rock mass strength using the numerical decomposition technique.

2.4.1 Use of the distinct element method to estimate rock mass strength

To use the distinct element method for stress analysis, first, the problem domain should be discretized into polygons in 2-D and polyhedra in 3-D. To achieve that for rock masses having finite size actual joint configurations, Kulatilake et al. (1992) and Wang and Kulatilake (1993) introduced some fictitious joints that behave as intact rock to interact with actual joints. After performing a detailed study under different stress paths, Kulatilake et al. (1992) provided recommendations to select proper mechanical property values for these fictitious joints to reflect the intact rock behavior. Using these techniques, detailed pioneering investigations have been performed to study the effect of finite-size joint geometry networks on the deformability and strength of jointed rock blocks, REV size, and equivalent continuum behavior at the 2-D (Kulatilake et al. 1994) and 3-D levels (Kulatilake et al. 1993; and 2004).

Results of these studies have shown anisotropic, scaledependent mechanical behavior for jointed rock masses. Also, an incrementally linear elastic, orthotropic constitutive model has been suggested at the 3-D level to represent the pre-failure mechanical behavior of jointed rock blocks (Kulatilake et al. 1993). This constitutive model has captured the anisotropic, scale-dependent behavior of jointed rock blocks. In that model, the effect of the joint geometry network in the rock mass

is incorporated in terms of the fracture tensor components which include the effect of all the joint geometry parameters - the number of joint sets, joint density, distributions of joint orientation, and size.

By performing numerical stress analyses in three perpendicular directions (x, y, and z) on different block sizes ranging between 5 m and 50 m, Wu and Kulatilake (2012) investigated the effect of a fracture system that existed in a limestone rock mass located at the Yujian River Dam site, China on rock block strength and deformability, REV sizes for mechanical properties and equivalent continuum behavior. The relation obtained between jointed rock block strength in the direction i/intact rock block strength (Si/SI) and block size for the investigated limestone rock mass is shown in Figure 1. This plot shows the scale effect, anisotropy, and REV behavior of rock mass strength. The unique relation obtained between the jointed rock block strength in the i direction/intact rock block strength (Si/SI) and the addition of the fracture tensor components in the j and k directions, which are perpendicular to the i direction is shown in Figure 2. Note that the fracture tensor component in a certain direction combines the effect of orientation and size probability distributions and the mean 3-D intensity of fractures coming from all the fracture sets in the rock mass in the selected direction (Kulatilake et al. 1993). The calculated values obtained from the three perpendicular directions are given in Figure 2. Also, at a refined level, an incrementally linear elastic, orthotropic constitutive model has been suggested to represent the pre-failure mechanical behavior of the jointed rock mass. In summary, these numerical studies have shown the possibility of developing relations between the rock mass strength and rock mass joint geometry properties. For further details on distinct element method applications, the reader is referred to the publications mentioned in Section 2.4.1.

Fig. 1 - Relation between the normalized rock block strength and block size (from Wu and Kulatilake 2012).

Fig 2. - Relation between the normalized rock block strength and relevant fracture tensor parameters (from Wu and Kulatilake 2012).

2.4.2 Use of PFC to estimate rock mass strength

Some investigators have resorted to particle flow codes (PFC2D and PFC3D) (Itasca 2003; Potyondy 2007; Ivars et al. 2011) to model jointed rock behavior under uniaxial loading (Kulatilake et al. 2001b; Koyama and Jing 2007; Bahaaddini et al. 2013; Gao et al. 2014; Fan et al. 2016), and bi-axial loading (Kulatilake et al. 2006). Kulatilake et al. (2001b) performed pioneering research in providing a realistic calibration procedure for micro-mechanical parameters of PFC3D for a contact-bonded particle flow model. Based on laboratory and PFC3D numerical modeling, Kulatilake et al. (2006) proposed a rock mass strength criterion for biaxial loading conditions. For details, the reader is referred to Kulatilake et al. (2006).

By selecting appropriate micro-mechanical parameter values through a trial-and-error procedure, Fan et al. (2016) used PFC3D to study the macro-mechanical behavior of jointed blocks having multi-non-persistent joints with high joint density under uniaxial loading. The focus was to study the effect of joint orientation, size, and joint mechanical properties on jointed block strength, deformability, stress-strain relation, and failure modes at the jointed block level. For details of the modeling and test results, the reader is referred to Fan et al. (2016) paper.

For further details on the PFC3D theory and applications, the reader is referred to the publications mentioned in Section 2.4.2.

3. RECENT DEVELOPMENTS ON ROCK MASS STRENGTH AT THE 3-D LEVEL

The Kulatilake et al. (2006) rock mass strength criterion developed for biaxial loading conditions was discussed in Sections 2.2 and 2.4.2. This criterion was extended to 3-D by He et al. (2017) based on true triaxial (polyaxial) laboratory test results and 3DEC numerical modeling on jointed coal blocks having non-persistent discontinuities. It was the first time any research group in the world developed a 3-D coal mass strength criterion incorporating non-persistent joint geometry parameters (orientation and size distributions and 3-D intensity) explicitly, and both σ3 and σ2. He et al. (2017) criterion is expressed below through Eqs. (1) and (2).

In Eq. (1), JCMS and ICS are the jointed coal mass strength and intact coal strength under the same combination of σ2 and σ3, respectively; F22 and F33 are the fracture tensor components in the directions of σ2 and σ3, respectively. In Eq. (2), ω incorporates the effect of σ3, as well as σ2; ω0 is the ω value for the uniaxial compression condition; ICSu is the intact coal strength under the uniaxial stress condition; a, b, c , and d are empirical coefficients to be determined by regression analysis. Figures 3 and 4 show a few typical relations obtained between the JCMS, different fracture systems, and the intermediate and minor principal stresses. For further details on this development and results, the reader is referred to He et al. (2017).

CB2 CB24 CB41

CB48 CB48SJS CB48CSJS

CB48MNSJS CB48MNIJS CB48MNLJS

In the aforementioned He et al. (2017) criterion, for a set of selected values of the σ2 and σ3, ω is a constant for a specified rock mass irrespective of the directions of σ2 and σ3 with respect to the fracture system in the rock mass. When σ2 and σ3 directions rotate around the vector normal to the plane of σ3 and σ3 (i.e. around the major principal stress, σ1, direction) the fracture tensor component in σ1 direction, F11 stays as a constant. Because the first invariant of the fracture tensor (F11 + F22 + F33) is always a constant, F22 + F33 also stays as a constant. Therefore, under the above-mentioned conditions, Eq. (1) provides the same value and cannot capture the effect of σ2 on F22 and the effect of σ3 on F33 separately in estimating the rock mass strength. However, this is an important issue to incorporate in estimating rock mass strength. This aspect was included in the rock mass strength criteria developed

Fig. 4 - Obtained relations between JCMS and σy for nine fracture network setups with σx = 2.367 MPa (from He et al. 2017).

Fig. 3 - Obtained relations between JCMS and σx for eight fracture network setups with σy = 7.101 MPa (from He et al. 2017)

by Mehranpour et al. (2018) using the conducted true triaxial (polyaxial) test results and PFC3D modeling. The rock mass strength criteria developed by Mehranpour et al. (2018) are expressed through Eqns. (3) and (4).

where λ2, λ3, ρ2, ρ3, q2 and q3 are empirical coefficients. In Eqs. (3) and (4), σJ and σ I are the jointed block strength and intact block strength, respectively, under the applied σ2 and σ3. In Eqn. (3), the number of empirical coefficients is high. Therefore, Mehranpour et al. (2018) developed a second rock mass strength criterion with fewer empirical coefficients, a2, a3, b2 and b3, as expressed in Eqn. (4).

FUNDING

The author’s research group performed research on the topic of rock joints and rock mass strength and deformability from time to time during the last 30 years. The funding for the research was provided by the US Department of Interior (grant number G1114101), Swedish Natural Science Research Council (contract numbers EEG3447313, CK526538, and CK632558), US National Science Foundation (Grant numbers CMS 9522798 and CMS 9740746), Metropolitan Water District of Southern California (Contract number 16040), Cyprus Sierrita Corporation (contract number (CK10240), Swedish Nuclear Fuel & Waste Management Company, and the Centers for Disease Control and Prevention, USA (Contract No. 200-201139886). The stated funding is highly appreciated.

ACKNOWLEDGEMENTS

For all the details of the procedures used and extensive rock mass strength criteria fitting results, the reader is referred to Mehranpour et al. (2018).

4. CONCLUSIONS

The most well-known rock mass strength criteria assume isotropy. Therefore, those have a chance of applying only to rock masses that are heavily fractured and do not have discontinuity sets with preferred orientation directions. On the other hand, most of the rock masses contain a few distinct discontinuity sets with statistically distributed discontinuity orientations and sizes. Such rock masses exhibit anisotropic, scale-dependent rock mass strength. In addition, the intermediate principal stress plays a major role in rock mass strength. The well-known rock mass strength criteria do not include the intermediate principal stress and do not have the capability of capturing the anisotropic, scale-dependent behaviour exhibited by most of the real-world rock masses. This author feels that a proper rock mass strength criterion in 3-D should incorporate the intermediate principal stress, the intensity of all the discontinuity sets and the probability distributions for orientations and size for all the discontinuity sets explicitly in the strength criterion. The 3-D rock mass strength criteria developed by He et al. (2017) and Mehranpour (2018) include the intermediate principal stress and the aforementioned discontinuity geometry parameters explicitly through the fracture tensor components to capture the scaledependent and anisotropic rock mass strength. However, He et al. (2017) and Mehranpour et al. (2018) rock mass strength criteria require further improvement at the deterministic level to enhance their capability in predicting failures resulting from all different modes for jointed blocks having non-persistent joints. Also, they require further modifications to include the joint weathering and infilling conditions and groundwater conditions. In addition, the improved deterministic He et al. (2017) and Mehranpour et al. (2018) criteria require extending to probabilistic versions by incorporating the variability and uncertainty associated with the estimation of discontinuity geometry parameters and discontinuity mechanical properties.

Several graduate students (Peng-fei He, M. Mehranpour, S Wang, J. Um, J. Park, B. Malama, H. Ucpirti, G. Radberg, J. Liang, and H. Gao)) and a few visiting scholars (Qiong Wu, and X. Fan) worked with the author in making contributions to the rock mass strength publications. All those efforts are highly appreciated.

REFERENCES

He, P.; Kulatilake, P.H.S.W.; Liu, D.; He, M. Development of a new 3-D coal mass strength criterion. International Journal of Geomechanics 2017, 17(3): 04016067, DOI: 10.1061/(ASCE) GM.1943-5622.0000741.

Hill, R. Elastic properties of reinforced solids: some theoretical principles. Journal of the Mechanics and Physics of Solids, 1963, 11(5): 357-372.

Kulatilake P.H.S.W. 3-D Rock mass strength criteria – review of current status. Geotechnics 2021, 1(1), 128-146; https://doi. org/10.3390/geotechnics1010007.

Mehranpour, M.H.; Kulatilake, P.H.S.W.; Xingen, M.; He, M. Development of new three-dimensional rock mass strength criteria. Rock Mechanics and Rock Engineering 2018, 51(11):3537-3561 https://doi.org/ 10.1007/s00603-018-1538-6.

Note: Since the length of the paper had to be limited, the rest of the citations given in the paper can be found in the References Section of Reference 3 given above.

SCIENCE

ACHIEVEMENT AWARD

Weiren Lin | Kyoto, Japan

APPLICATIONS OF IN-SITU STRESS MEASUREMENTS TO ACTIVE FAULT DRILLING PROJECTS

This article illustrates the recipient’s activities on his one major research topic: in-situ stress state of rock mass in deep-subsurface, e.g., stress measurements, geomechanical and scientific interpretations of measured stress states, developments of stress measurement methods, through applications to two active fault drilling projects of the Japan Trench Fast Drilling Project (JFAST) and the Taiwan Chelungpu-fault Drilling Project (TCDP).

1. INTRODUCTION

Stress and earthquakes are known to be interrelated: stress triggers earthquakes and earthquakes alter the shear and normal stresses on surrounding faults. To understand the physics of earthquake occurrence and the propagation mechanism of fault rupturing, the applications of in-situ stress measurements to earthquake-source fault drilling projects have been studied by the author for several decades.

After a brief review of stress indicators of borehole wall failures, stress measurements based on borehole wall failures in two active fault drilling projects conducted by the Integrated Ocean Drilling Program (IODP) using a drilling vessel (D/V) Chikyu (Fig 1) and the International Continental Drilling Project (ICDP), respectively, are described.

This article describes previous research focusing on insitu stress measurements applied to two case studies of earthquake-source faults ruptured after the 2011 Mw 9.0 Tohoku, Japan earthquake and the 1999 Mw 7.6 Chi-Chi, Taiwan earthquake. The first one refers to the determination of the stress state in the vicinity of the ruptured plate boundary fault and stress drop accompanied by the 9.0 Tohoku earthquake;

the second one concerned the characterization of the stress distribution in the borehole penetrating the Chelungpu-fault ruptured during the Chi-Chi earthquake.

2. STRESS INDICATORS OF BOREHOLE WALL FAILURES

2.1 Two stress indicators of borehole wall failures Drilling a borehole in subsurface rock mass may induce stress concentration around the borehole wall. Based on the elastic theory, the maximum and intermediate principal stresses, hoop (circumferential) stress σθ and vertical stress σz vary with azimuth θ as a trigonometric function in a far field Andersonian in-situ stress environment, whereas the minimum principal stress radial stress σr keeps constant being equal to the mud pressure in the borehole (Fig 2). Here the azimuth θ is defined as the angel anticlockwise from the azimuth of the minimum horizontal stress Shmin (see Fig 3). Simply, if the maximum hoop stress σθ on the borehole wall reaches the rock compressive strength (the horizontal dashed line in Fig 2), a pair of compressive failures called borehole breakout or breakout occur on the borehole wall at the same azimuth as Shmin (Fig 3). On the other hand, if the minimum hoop stress σθ becomes a negative (tensile) stress possibly caused by a high mud pressure and reaches the rock tensile strength, a pair of tensile fractures called drilling induced tensile fracture (DITF) occur on the borehole wall at the same azimuth as the maximum horizontal stress SHmax

Because both breakouts and DITFs are dependent on in-situ stress conditions, we can use information on their azimuths to determine orientations of in-situ principal stresses in the plane perpendicular to the borehole axis (e.g., Zoback 2007). As breakouts and DITFs both form during or shortly after drilling, they are records of the stress state at the time of drilling. Breakouts and DITFs can be recorded in various types of borehole wall image logs (resistivity log, sonic log and optical camera log), and breakouts can also be recorded in fore-arms or six-arms caliper log occasionally (e.g., Fig 4).

Fig. 1 - The D/V Chikyu used for IODP drilling projects from 2007.

Fig. 2 - Conceptual change patterns of three principal stress magnitudes on the borehole wall with azimuth. Here, the azimuth θ=0° is the same as the orientation of the minimum horizontal stress Shmin (Fig 3).

Fig. 3 - Schematic borehole cross section with a pair of breakouts showing relationship between breakout position and maximum/minimum horizontal stress azimuth (modified from Haimson et al., 2010).

Fig. 4 - An example of an image log of UBI (Ultrasonic Borehole Imager) with borehole breakouts and drilling-induced tensile fractures (DITFs) (modified from Zoback et al., 2003). The breakouts are manifest as dark bands (low reflection amplitudes) on opposite sides of the borehole wall. Note also the existence of DITFs ~90° from the breakouts.

2.2 Borehole breakout

In a vertical borehole, breakouts form an elongation of the borehole in the azimuth of the minimum horizontal stress Shmin and perpendicular to the maximum horizontal stress SHmax (Fig 2 and 3). Thus, breakout azimuths can be used to simply determine azimuths of Shmin; and to determine the azimuths of SHmax by rotating 90° from Shmin. I usually identify breakouts as stress indicators according to following criteria (Lin et al., 2007). The criteria are as (1) breakouts are wider than a fracture and do not have sharp, straight boundaries like a tensile fracture does, (2) breakouts must occur in pairs and in two opposite positions, that is, not on only one side of the borehole wall, and (3) breakouts have a certain length e.g., longer than approximately 0.5 m.

When the maximum hoop stress is higher than the rock compressive strength, therefore a pair of rock compressive failures (i.e. breakouts) initiate from locations on borehole wall at Shmin azimuths and extend progressively, and then stops at the edges (B and B’ in Fig 3) where the stress state and the rock strength are under a mechanical equilibrium state (B and B’ in Fig 2). According to this mechanical equilibrium state, equation(s) between stress magnitude and the rock strength can be built based on a rock compressive failure criterion. Thus, using the equation(s), the stress magnitudes can be constrained on the basis of width (span) of breakouts and rock strength data (Zoback, 2007). However, constrained stress magnitudes depend on the utilized criteria of rock compressive failures, for example, Mohr-Coulomb criterion which ignores intermediate stress effects on strength and modified Wiebols and Cook criterion which takes the intermediate stress effects into (Fig 5). For details, see a case study of Lin (2014)

Fig. 5 - A comparison of stress constraints from the same breakout data but based on Mohr-Coulomb (MC; shown by red area) and modified Wiebols and Cook (mWC; blue area) criteria, respectively in a stress polygon (after Lin, 2014). RF shows the region of reverse faulting stress regime; SS: strike-slip faulting stress regime and NF: normal faulting stress regime. WOB is width of breakout, that is, the 2b shown in Fig 3. In this model case, the mean of WOB is 59°, and its standard deviation is 22°. Clearly the possible stress area of mWC model differed with the area of the MC mode.

2.3 Drilling induced tensile fracture (DITF)

In a vertical borehole, DITFs occur on the borehole wall in the azimuth of the maximum horizontal stress SHmax and perpendicular to the maximum horizontal stress Shmin in case of a negative/tensile hoop stress (Fig 2). Usually, the DITFs in a vertical borehole extend in a vertical direction through the borehole axis (Fig 4). Similar to the breakouts, DITF azimuths can be used to simply determine azimuths of SHmax; and to determine the azimuths of Shmin by rotating 90° from Shmin. I usually identify breakouts as stress indicators according to following criteria similar as those of breakouts (Lin et al., 2007). The criteria are as (1) DITFs are narrow, (2) DITFs must occur in pairs and in two opposite positions, that is, not on only one side of the borehole wall, and (3) DITFs have a certain length e.g., longer than approximately 0.5 m.

3. APPLICATION TO THE DRILLING PROJECT

PANETRATING THE MW 9.0 TOHOKU EARTHQUAKE

SOURCE FAULT

3.1 Japan trench fast drilling project (JFAST)

During the 11 March 2011 Mw 9.0 Tohoku, Japan, earthquake, the plate boundary megathrust ruptured and reached the sea floor at the axis of the Japan trench, and produced a maximum coseismic slip of >50 m close to the Japan trench, triggering a devastating tsunami. To understand the mechanisms more clearly for the record-breaking displacement of the coseismic slip, the IODP conducted Expedition 343 and 343T, named the Japan Trench Fast Drilling Project (JFAST), to drill through the plate boundary fault. This drilling from the seafloor under an ~7 km water depth was rapidly undertaken by the D/V Chikyu (Fig 1) approximately one year after the earthquake at site C0019 (Fig 6 and 7). The drilling site C0019 is located in an area of the largest coseismic slip zone of more than 50 m, ~93 km seaward of the epicenter of the Mw 9.0 earthquake and ~6 km landward of the Japan trench axis (Fig 6). Three boreholes successfully penetrated the plate boundary fault between the subducting Pacific Plate and the overriding North American Plate. The project investigated the mechanisms of the great coseismic slip that caused the devastating tsunami by

conducting stress measurements in the borehole, sampling the plate boundary fault, and making temperature measurements across the ruptured fault (Mori et al., 2014).

3.2 Stress changes accompanying with the Mw 9.0 earthquake

To investigate the stress change associated with the Tohoku earthquake, I and my colleagues analyzed borehole breakouts recognized from the LWD (Logging While Drilling) borehole images (Fig 8) to determine in-situ stress azimuths and to constrain stress magnitudes. In a depth interval of 537–813 meters below seafloor (mbsf) consisting of mudstone with porosity of ~45±3% within the accretionary prism and above the plate boundary fault at 820 mbsf, the SHmax azimuth has a clear preferred orientation in a northwest-southeast direction (319±23°) (Fig 6). This stress orientation is consistent with the plate convergence direction, and also roughly consistent with stress orientations determined at sites 1150 and 1151 (Fig 6).

The possible range of SHmax and Shmin magnitudes were constrained by a stress polygon, observed widths of breakouts and unconfined compressive strengths (UCS) based on the modified Wiebols and Cook criterion for two depth intervals around 720 and 812 mbsf above the plate boundary fault (Fig 9). The stress polygons are based on the Anderson theory of faulting with coefficient of sliding friction of 0.6. As the stress regime must lie inside the polygon defined by the vertical stresses (SV) and assumed friction coefficient, only a restricted range of values of SHmax and Shmin are possible. Three triangle areas labeled as NF, SS and RF in the polygon (Fig 9 (a) and (c)) show the normal faulting (NF), strikeslip faulting (SS) and reverse faulting (RF) stress regimes, respectively. Assuming an Andersonian stress states and SV calculated from the sedimentary rock density profile: the values of SV, SHmax and Shmin at 720 mbsf are approximately the maximum, intermediate and minimum principal stresses, respectively. At 812 mbsf, however, there is some uncertainty if SHmax is necessarily less than SV; the constrained stress state is close to the boundary of the normal faulting and strikeslip faulting regimes. Overall, these results indicate that the

Fig. 6 - Location of drilling site C0019 of JFAST and SHmax orientation above the plate boundary fault. Red solid and dashed lines show the mean SHmax orientation in Log unit IIb and one standard deviation (SD), respectively (Lin et al., 2013). Green circles and lines indicate sites drilled in 1999 and their SHmax orientations prior to the 2011 Tohoku earthquake (Lin et al., 2011). Red star shows the epicenter of the Mw 9.0 earthquake, the gray arrow shows relative plate motion (Argus et al., 2011). The white line around site C0019 indicates the location of Fig 7. This map was modified from Lin et al., 2013, 2014 and 2023.

Fig. 7 - Interpreted inline seismic profile (HD33B) crossing site C0019 (Chester et al., 2013). It shows the location of the boreholes (red vertical lines), frontal prism and trench, the normal-faulted basal pelagic sediments and oceanic basalt, and the interpreted location of the plate boundary fault and associated faults in the sediments. mbsl: meters below sea level; V.E.: vertical exaggeration.

Fig. 8 - Unwrapped and three-dimensional borehole wall electrical images obtained by LWD show the presence of borehole breakouts, which occur on the borehole wall and appear on the electrical image as a pair of vertical black bands (conductive bands) approximately 180° apart (Expedition 343/343T Scientists, 2013).

Fig. 9 - Constraints on horizontal stress magnitudes at 720 mbsf (a, b) and at 812 mbsf (c, d), respectively (Lin et al., 2013). The red and blue curves in (b) at 720 mbsf show that the lower and upper stress conditions for WOB of 58±22° (mean ± SD) and ∆P (difference of mud pressure and pore pressure) of 0 and 0.8 MPa, respectively, locate within the NF regime. Hatched area is the constrained horizontal stress magnitude range. Red and blue curves in (d) at 812 mbsf show the stress conditions for WOB of 59±22°, ∆P of 0 and 0.9 MPa, and UCSs of 6.4 and 7.6 MPa, respectively. The constrained range for 812 mbsf is around the boundary of NF and SS regimes. Red bars on the axes (b, d) give the possible ranges of SHmax and Shmin magnitudes, respectively.

post-earthquake stress states in the frontal prism are either in or close to the normal faulting stress regime (Lin et al., 2013).

The frontal portion of the accretionary wedge is considered to have been under trench-normal compression prior to the Tohoku earthquake, on the basis of the orientations of minor faults and beddings observed in the logging data and in core samples. Therefore, it was concluded that the stress state in the frontal prism has changed from a reverse faulting regime before the earthquake to the present normal faulting, or near normal faulting regime as shown in Fig 10. Before the earthquake, it was commonly known that each

earthquake generally released only part of the stress driving the earthquake fault. However, these stress measurement results based on borehole breakout analyses (Lin et al., 2013; Brodsky et al., 2017) and anelastic strain recovery (ASR) method reported by Lin et al. (2023) suggested a completed stress drop and a large energy release during the earthquake. Therefore, this completed stress drop might increase the coseismic fault slip and result in the devastating tsunami. This research discovered the unexpected stress drop during the huge earthquake using real stress measurement data by rockmechanical approaches.

Fig. 10 - Schematic of inferred coseismic three-dimensional stress state change during the Tohoku earthquake in the lower portion of the frontal prism (modified from Lin et al., 2013).

regional structures,

section (modified from Lin et al., 2010). (a) Tectonic setting of Taiwan and location of the 1999 Chi-Chi earthquake epicenter. (b) Geological map showing the formation distribution and several faults in the central portion of the western Taiwan and the TCDP site (red star). Chelungpu-fault (red line) ruptured during the 1999 earthquake. The focal mechanism shows the epicenter of the earthquake. (c) Cross section through the drill site illustrates the relation between formations and major fault zones (after Yeh et al., 2007). The dashed frame in (a) shows the area of (b); and the dashed line in (b) shows the location of (c).

4. APPLICATION TO TAIWAN CHELUNGPU-FAULT DRILLING PROJECT

4.1 Taiwan Chelungpu-fault drilling project (TCDP)

During the huge, destructive Chi-Chi earthquake (Mw 7.6) occurred in west-central Taiwan in 21st September 1999, the Chelungpu-fault ruptured as a result of convergence of the Philippine Sea and Eurasian plates (e.g., Yeh et al., 2007). The Chelungpu fault dips gently to the east (30°), and slips principally within and parallel to the bedding of the Pliocene Chinshui Shale (Fig 11). To understand the physics of the earthquake and the mechanism of fault rupturing propagation, the Taiwan Chelungpu-fault Drilling Project (TCDP) supported by ICDP drilled two vertical holes 40 m apart (hole A to ~2000 m and hole B to ~1350 m) about 2 km east of the surface rupture (Ma et al., 2006). The TCDP hole B penetrated the major fault zone ruptured in the earthquake at a depth of 1111 m within the Chinshui Shale (e.g., Lin et al., 2007).

4.2 Local stress changes observed from borehole images

A main objective of the TCDP was to determine the spatial distribution of the in-situ stress and, in particular, to determine the stress state on and around the fault plane before, during, and after the earthquake. I and my colleagues carried out stress analyses, using both borehole breakouts and DITFs in TCDP hole B (Lin et al., 2007a and 2010), and other independent stress measurements such as the ASR method (Lin et al., 2007b) and the hydraulic fracturing tests (Haimson et al., 2010). Here, I introduce some stress measurement results of

breakout and DITF analyses accompanied by core descriptions to show local stress changes observed from borehole images.

As the first example, Fig 12 shows an abrupt, drastic change in the orientation of the principal horizontal stresses observed in the vicinity of a minor fault at 1119.7 m. The core sample diameter (Fig 12–14) is approximately 83 mm, and the constriction ratio of the core photographs in the vertical and lateral directions is 2:1. As shown in Fig 12, the minor fault, which was interpreted as a left-lateral strike-slip fault with normal slip from description of cores, has a large dip angle (dip/dipping direction: 70°/050° approximately). The azimuth of the breakout abruptly rotates by approximately 90° (Fig 12a and 12d). Therefore, at the minor fault depth, the orientation of SHmax changed roughly from the rupturing direction of the earthquake source fault to that perpendicular to the rupturing direction. The minor fault at 1119.7 m, where the SHmax azimuth abruptly rotated, is the boundary between the normal stress orientation consistent with the regional stress orientation, and an anomalous stress orientation caused by the 1999 earthquake (Lin et al., 2007a; Lin et al., 2010).

The second example of abrupt rotations in stress orientation (Fig 13) was identified on the basis of DITFs. Across two adjacent fractures (around 1031.0 m; dip/dipping direction: 30°/120°; approximately parallel to bedding of the Chinsui Shale), the locations of the DITFs, which are the same as the azimuths of SHmax, abruptly rotated by 12° approximately. For this example, the main reason that induced abrupt stress rotation might be presence of the fractures. Around a lithologic

Fig. 11 - Schematic diagram illustrating the tectonics,

geological

(a)

(c)

(b)

Fig. 12 - An example of abrupt stress orientation changes in the vicinity of a minor fault at 1119.7 m (Lin et al., 2010). (a) FMI electrical image; the left edge corresponds to north. Dark colors in the image represent conductive areas and light colors resistive areas. (b) An optical photograph of the flat surface of a half-core split in the vertical plane approximately parallel to the downdip direction. (c) An optical photograph of the cylindrical core. (d) Plots of the SHmax azimuths over a depth range of several meters around this minor fault.

Fig. 13 - Examples of an abrupt but minor stress orientation change across two adjacent fractures (around 1031.0 m) determined from DITFs and breakout suppression at the lithologic boundary (1032.2 m) (Lin et al., 2010). (a and c) Optical images of the flat surface of the half-core split. (b) FMI electrical image.

boundary at ~1332.2 m, DITFs and breakouts occurred in different lithologies respectively, suggesting different stress-states in the different lithologies (Fig 13b and 13c).

The next example shows gradual change in stress orientation in the vicinity of faults and fractures (Fig 14). Immediately below a minor fault (approximately 3 cm thick at 975.4 m; 30°/130° approximately) (Fig 14a–c), breakouts identified show gradual rotating below the fault by 90° approximately over a depth interval of 2.6 m, until reaching another fracture at 978.0 m. Below this fracture (978.0 m), the breakouts do not rotate but maintain an almost constant azimuth consistent with the regional stress orientation. Because the gradual stress rotation is local and the lithologies in hanging and foot walls are almost same (Fig 14a and 14b), the rotation might be interpreted due to presences of the minor fault.

Fig. 14 - A gradual change in the stress orientation below a minor fault (975.4 m), and breakout suppression at the same minor fault, and an example of same stress orientations across a fracture (978.0 m) (Lin et al., 2010). (a and f) Optical photographs of the cylindrical core. (b and e) Optical images of the flat surface of the half-core splits. (c) FMI electrical image. (d) Plot of the SHmax azimuths over the corresponding depth interval.

5. CONCLUSION

The use of stress measurements data obtained by rock mechanics approaches in active fault drilling projects following the 2011 Mw 9.0 Tohoku earthquake and the 1999 Mw 7.6 ChiChi earthquake led to the detection of unexpected stress drops in vicinity of the earthquakes source faults. This finding marked a significant leap forward in understanding the correlation between earthquake occurrences and stress changes, highlighting the important role of stress measurements in seismic research.

ACKNOWLEDGEMENT

It was a great honor to receive the ISRM 2024 Science Achievement Award after having dedicated more than 30 years to rock mechanics research in both geoengineering and geoscience areas. I wish to thank the Japanese Society for Rock Mechanics for recommending my nomination and the ISRM Board for the great honor of being selected as the winner of this award. Many colleagues have given me great helps in my research journey, but they are too many to be listed here. I am also grateful to IODP, TCDP for providing research data and rock samples, and financial supporting from JSPS KAKENHI.

REFERENCES

Argus D.F., Gordon R.G., DeMets C., 2011. Geologically current motion of 56 plates relative to the no-net-rotation reference frame. Geochem. Geophys. Geosyst., 12, Q11001, https://doi. org/10.1029/2011GC003751.

Brodsky E.E., Saffer D., Fulton P., Chester F., Conin M., Huffman K., Moore J.C., Wu H.-Y., 2017. The postearthquake stress state on the Tohoku megathrust as constrained by reanalysis of the JFAST breakout data. Geophys. Res. Lett., 44, 8294–8302, https://doi.org/10.1002/2017GL074027.

Chang C., McNeill L., Moore J. C., Lin W., Conin M., & Yamada Y., 2010. In situ stress state in the Nankai accretionary wedge estimated from borehole wall failures, Geochem. Geophys. Geosyst., 11, Q0AD04, https://doi.org/10.1029/2010GC003261.

Chester F.M., Rowe C., Ujiie K. et al., 2013. Structure and Composition of the plate-boundary slip zone for the 2011 Tohoku-Oki earthquake. Science, 342, 1208-1211, https://doi. org/10.1126/science.1243719.

Expedition 343/343T Scientists, 2013. Site C0019. In Chester F.M. et al. (Eds), Proc. IODP, 343/343T: Tokyo (IODP Management International, Inc.), https://doi.org/10.2204/iodp. proc.343343T.103.2013.

Haimson B., Lin W., Oku H., Hung J-H., & Song S-R., 2010. Integrating borehole breakout dimensions, strength criteria, and leak-off test results, to constrain the state of stress across the Chelungpu Fault, Taiwan, Tectonophysics, 482, 65–72, https://doi.org/10.1016/j.tecto.2009.05.016.

Lin W., Yeh E-C., Ito H. et al., 2007a, Current stress state and principal stress rotations in the vicinity of the Chelungpu fault induced by the 1999 Chi-Chi, Taiwan, earthquake, Geophys. Res. Lett., 34, L16307, https://doi.org/10.1029/2007GL030515.

Lin W., Yeh E.-C., Ito H. et al., 2007b. Preliminary results of stress measurement by using drill cores of TCDP Hole-A: an application of anelastic strain recovery method to three-

dimensional in-situ stress determination, Terr. Atmos. Ocean. Sci., 18, https://doi.org/10.3319/TAO.2007.18.2.379(TCDP).

Lin W., Yeh E-C., Hung J-H., Haimson B., Hirono T., 2010. Localized rotation of principal stress around faults and fractures determined from borehole breakouts in hole B of the Taiwan Chelungpu-fault Drilling Project (TCDP), Tectonophysics, 482, 82-91, https://doi.org/10.1016/j. tecto.2009.06.020.

Lin W., Saito S., Sanada Y., Yamamoto Y., Hashimoto Y., Kanamatsu T., 2011. Principal horizontal stress orientations prior to the 2011 Mw 9.0 Tohoku-Oki, Japan, earthquake in its source area, Geophys. Res. Lett., 38, L00G10, https://doi. org/10.1029/2011GL049097.

Lin W., Conin M., Moore J.C., Chester F.M., Nakamura Y., Mori J.J., Anderson L., Brodsky E.E., Eguchi H., Expedition 343 Scientists, 2013. Stress state in the largest displacement area of the 2011 Tohoku-Oki earthquake, Science, 339, 687–690, https://doi.org/10.1126/science.1229379.

Lin W., 2014. Constraining the magnitudes of maximum and minimum horizontal stresses from borehole breakouts – A comparison between different rock failure criteria, in Alejano, Perucho, Olalla & Jiménez (Eds), Proceedings of European Rock Mechanics Symposium 2014, CRC Press, 1347–1350, Vigo, Spain.

Lin W., Fulton P.M., Harris R.N. et al., 2014. Thermal conductivities, thermal diffusivities, and volumetric heat capacities of core samples obtained from the Japan Trench Fast Drilling Project (JFAST), Earth, Planets and Space, 66, 48, https://doi.org/10.1186/1880-5981-66-48.

Lin W., Yamamoto Y. and Hirose T., 2023. Three-dimensional stress state above and below the plate boundary fault after the 2011 Mw 9.0 Tohoku earthquake, Earth and Planetary Science Letters, 601, 117888, https://doi.org/10.1016/j. epsl.2022.117888.

Ma K.-F., Tanaka H., Song, S.-R. et al., 2006. Slip zone and energetics of a large earthquake from the Taiwan Chelungpufault Drilling Project, Nature, 444, 473–476, https://doi. org/10.1038/nature05253.

Mori J., Chester F., Brodsky E., Kodaira S., 2014. Investigation of the huge tsunami from the 2011 Tohoku-Oki, Japan, earthquake using ocean floor boreholes to the fault zone. Oceanography, 27, 132–137, https://doi.org/10.5670/ oceanog.2014.48.

Yeh E.-C., Sone H., Nakaya T. et al, 2007. Core description and characteristics of fault zones from Hole-A of the Taiwan Chelungpu-fault Drilling Project. Terr. Atmos. Ocean. Sci., 18, 327–357, https://doi.org/10.3319/TAO.2007.18.2.327(TCDP).

Zoback M.D., Barton C.A., Brudy M. et al., 2003, Determination of stress orientation and magnitude in deep wells, Int. J. Rock Mech. Min. Sci., 40, 1049–1076.

Zoback M.D., 2007, Reservoir Geomechanics, https://doi. org/10.1017/CBO9780511586477, Cambridge Univ. Press, New York.

ISRM CORPORATE MEMBERS IN 2024

A - SUPPLIERS OF ROCK MECHANICS EQUIPMENT AND MATERIALS

Applied Seismology Consulting, United Kingdom

Beijing Anke Technology Co. Ltd., China

Bekaert Svenska AB, Göteborg, Sweden

China University of Mining and Technology, Beijing, China

ESS Earth Sciences, Melbourne, Australia

Fondasol, Avignon, France

GCTS Testing Systems, Tempe AZ, USA

Geobrugg, Romanshorn, Switzerland

Geobrugg Andina, Lima, Peru

EOS Ingénieurs Conseils, Courbevoie, France

Glötzl, Rheinstetten, Germany

Guangdong Hongda Blasting Engineering Co. Ltd., China

Katecs Co. Ltd., Japan

KFC Ltd., Japan

LKAB-Wassara AB, Norway

LNEC - Laboratório Nacional de Engenharia Civil, Lisbon, Portugal

MTS System Corporation, Éden Prairie, USA

National Institute of Natural Hazards, China

NGE Fondations, France

Oyo Corporation, Tokyo, Japan

Pagani Geotechnical Equipment, Calendasco, Italy

Sibelco NordicAS Avd Stjernøy, Alta, Norway

Solexperts Ag., Mönchaltorf, Switzerland

TechFab India Industries Ltd., India

B SUPPLIERS OF ROCK MECHANICS SERVICES

AF Grupen Norge AS, Oslo, Norway

Alliance Geotechnical Pty Ltd., Seven Hills, Australia

Applied Seismology Consulting, United Kingdom

Beck Engineering Pty Ltd., Chatswood, Australia

Beijing Anke Technology Co. Ltd., China

Bekaert Svenska AB, Göteborg, Sweden

Bergab AB, Solna, Sweden

Besab AB Hisings Backa, Sweden

Chalmers University of Technology, Göteborg, Sweden

China University of Mining and Technology, Beijing, China

DynaFrax UG, Ltd., Germany

Enzan Koubou Co. Ltd., Japan

ESS Earth Sciences, Richmond, Australia

FF Geomechanics Ing. Ltda., Arequipa, Peru

Fondasol, Avignon, France

Geobrugg, Romanshorn, Switzerland

Geobrugg Andina, Lima, Peru

GEOS Ingénieurs Conseils, Courbevoie, France

Geoscience Ltd., Falmouth, United Kingdom

Geoconsult ZT GmbH, Austria

Ineris, Verneuil en Halatte, France

Ingenieursozietät Prof. Dr.-Ing. Katzenbach Gmbh, Frankfurt am Main, Germany

Institute of Geology and Geophysics,Chinese Academy of Geological Sciences, China

Institute of Rock and Soil Mechanics, Chinese Academy of Science, Wuhan City, China

LECM - Civil Engineering Laboratory of Macau, Macau, China

LLC Science Development Company „Mining Geomechanics, Russia

LNEC - Laboratório Nacional de Engenharia Civil, Lisbon, Portugal

National Institute of Natural Hazards, China

Nick Barton and Associates, Høvik, Norway

Nitro Consult Ab., Stockholm, Sweden

Norconsult AS, Sandvika, Norway

Oyo Corporation, Tokyo, Japan

Rejlers Sverige AB, Sweden

Rocscience LaTam, Lima, Peru

RISE Research Institute of Sweden, Borås, Sweden

Royal Institute of Technology - KTH, Stokholm, Sweden

SC GEOSTUD SRL, Romania

Solexperts Ag., Mönchaltorf, Switzerland

State Key Lab. For Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing, China

Sweco AB, Stockholm, Sweden

Swedish Nuclear Fuel and Waste Management, SKB AB, Figeholm, Sweden

Tractebel Engineering, Gennevilliers, France

Trilab Pty Ltd., Geebung, Australia

WSP Sverige AB, Stockholm-Globen, Sweden

C CONSULTANTS

AF Grupen Norge AS, Oslo, Norway

AFRY, Solne, Sweden

AGL Consulting, Dublin, Ireland

Alliance Geotechnical Pty Ltd., Seven Hills, Australia

Applied Seismology Consulting, United Kingdom

Bauer Spezialtiefbau Schweiz AG, Switzerland

Beck Engineering Pty Ltd., Chatswood, Australia

Bergab AB, Solna, Sweden

Bekaert Svenska AB, Göteborg, Sweden

Besab AB Hisings Backa, Sweden

BG Ingénieurs Conseils SA, Switzerland

Cartledge Mining & Geotechnics, Brisbane, Australia

CETU (Centre d’Études des Tunnels), Lyon, France

Chalmers University of Technology, Göteborg, Sweden

Changjiang River Scientific Research Institute, Wuhan, China

Changjiang Survey Planning Design Research Co. Ltd., China

Chengdu Engineering Co. Ltd:Ç, PowerChina; China

China Academy of Railway Sciences Co. Ltd., China

China Coal Technology & Engineering Group (CCTEG), Beijing, China

China Railway 18th Bureau Group Tunnel Engineering Co. Ltd., China

China Three Gorges Corporation, China

China University of Mining and Technology-Beijing, China

China University of Petroleum-Beijing, China

Chuo Kaihatsu Corporation, Tokyo, Japan

Dia Consultants Co. Ltd., Tokyo, Japan

DL E&C, Korea

DMEC - Dong Meyong Engineering Consultants & Architecture Co. Ltd., Seoul, Korea

Docon Corporation, Hokkaido, Japan

DynaFrax UG, Ltd., Germany

Electric Power Dev. Co. Ltd., Tokyo, Japan

MEMBERS

ESS Earth Sciences, Richmong, Australia

FF Geomechanics Ing. Ltda., Arequipa, Peru

Fondasol, Avignon, France

GeoConnect Technology Development Co. Ltd., China

Geoscience Ltd., Falmouth, United Kingdom

Geoconsult ZT GmbH, Austria

Geomind KB, Stockholm, Sweden

Glötzl, Rheinstetten, Germany

Guangdong Hongda Blasting Engineering Co. Ltd., China

Hanjiang-yo-Weihe River Valley Water Diversion Projet Construction Co.Ltd., Shaanxi Province, China

Hazama Corporation, Ibaraki, Japan

HJ Shipbuilding & Construction Co., Ltd., Korea

Hubei University of Technology, China

Hydrogeotechnique, Fontaines, France

Implenia Suisse SA, Switzerland

Ineris, Verneuil en Halatte, France

Ingenieursozietät Prof. Dr.-Ing. Katzenbach Gmbh, Frankfurt am Main, Germany

Institute jsc " VNIMI", St. Petersburg, Russia

Institute of Complex Development of Mineral Resources of the RAS, Moscow, Russia

Institute of Geology and Geophysics, Chinese Academy of Geological Sciences, China

Institute of Mining Siberian Branch of RAS, Novosibirsk, Russia

Institute of Mining, Far Eastern Branch of the RAS, Khabarovsk, Russia

ITOCHU Techno – Solutions Corporation, Tokyo, Japan

J-Power Engineering Co. Ltd., Japan

Japan Conservation Engineers & Co. Ltd., Japan

Japan Underground Oil Storage Group Comp., Tokyo, Japan

Kajima Technical Research Institute, Tokyo, Japan

Kawasaki Geological Engng. Co. Tokyo, Japan

Kiso-Jiban Consultants Co. Ltd., Tokyo, Japan

Kolong Global Corporation, Korea

LCW Consult, S.A., Algés, Portugal

LLC Science Development Company „Mining Geomechanics, Russia

LNEC - Laboratório Nacional de Engenharia Civil, Lisbon, Portugal

Locher Ingenieure AG, Zurich, Switzerland

Lombardi Engineering Ltd., Minusio, Switzerland

Lombardi SA, Switzerland

LOTTE E&C, Seoul, Korea

Multiconsult Norge AS avd Oslo, Norway

National Institute of Natural Hazards, China

Newjec Inc., Osaka, Japan

NGE Fondations, France

Nick Barton and Associates, Høvik, Norway

Nishimatsu Construction CO. Ltd., Tokyo, Japan

Nitro Consult Ab., Stockholm, Sweden

Norconsult AS, Sandvika, Norway

NTNU Inst for Geologi og Bergteknikk, Trondheim, Norway

Ove Arup & Partners Ltd., London, UK

Perm National Research Polytechnic University, Perm, Russia

Posco E&C, Korea

Prof. Quick und Kollegen, Darmstadt, Germany

Ramböll Sverige, Stockholm, Sweden

RCC-Group, Moscow, Russia

Rejlers Sverige AB, Sweden

RISE Research Institute of Sweden, Borås, Sweden

Research Institute of Experiment and Detection, Xinjiang Oilfield Company, Petro China, China

Royal Institute of Technology - KTH, Stokholm, Sweden

SAMSUNG C&T, Korea

SC GEOSTUD SRL, Romania

Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering, Xauat, China

Shandong University, China

Shijiazhuang Tiedao University, China

SK E&C, Seoul, Korea

Skanska AB, Solna, Sweden

Solexperts Ag., Mönchaltorf, Switzerland

Storengy, France

Suncoh Consultants Co. Ltd., Tokyo, Japan

Sweco AB, Stockholm, Sweden

Sweco Norge AS, Oslo, Norway

Swedish Nuclear Fuel and Waste Management Co. – SKB, Stockholm, Sweden

Swedish Rock Engineering Association, Sweden

Temro Corporation, Japan

Terrasol, France

Tetra Tech Coffey, Australia

Tongji University, Shaghai, China

Tractebel Engineering, Gennevilliers, France

Tyréns AB, Stockholm, Sweden

WSP Sverige AB, Stockholm-Globen, Sweden

Yachiyo Engineering Co. Ltd., Tokyo, Japan

D CONTRACTORS

Changjiang River Scientific Research Institute, Wuhan, China

Chemical Grouting Co., Ltd, Tokyo, Japan

China Academy of Railway Sciences Co. Ltd., China

China Coal Technology & Engineering Group (CCTEG), Beijing, China

China University of Mining and Technology-Beijing, China

Docon Corporation, Hokkaido, Japan

DynaFrax UG, Ltd., Germany

Engigeo - Engenharia Geotécnica, Lda, Portugal

ESS Earth Sciences, Richmong, Australia

Geoscience Ltd., Falmouth, United Kingdom

Glötzl, Rheinstetten, Germany

Hanjiang-To-WeiheRiver Valley Water Diversion Projet Construction Co. Ltd., Shaanxi Province, China

Japan Underground Oil Storage Comp., Tokyo, Japan

Kajima Technical Research Institute, Tokyo, Japan

Lombardi SA, Minusio, Switzerland

NGE Fondations, France

Nishimatsu Construction Co. Ltd., Tokyo, Japan

Obayashi Corporation, Tokyo, Japan

Shandong Innovative Material Technology Co. Ltd., China

Shimizu Corporation, Tokyo, Japan

Skanska Norge AS, Oslo, Norway

Solexperts Ag., Mönchaltorf, Switzerland

Sweco Norge AS, Oslo, Norway

Taisei Corporation, Tokyo, Japan

Tekken Corporation, Tokyo, Japan

Tobishima Corp., Chiba, Japan

Toda Corporation, Tokyo, Japan

MEMBERS

Tongji University, Shaghai, China

Vinci Construction Grands Projets, France

Zhejiang Society for Geotechnical Mechanics & Engineering, China

E ELECTRICITY SUPPLY COMPANIES

China University of Mining and Technology, Beijing, China

Chugoku Electric Power Co. Inc., Hiroshima, Japan

Electric Power Dev. Co. Ltd., Tokyo, Japan

Hokkaido Electric Power Co. Inc., Hokkaido, Japan

Shandong University, China

Shikoku Electric Power Co. Kagawa, Japan

Southwest Jiaotong University, China

F MINING COMPANIES

Boliden Mineral AB, Boliden, Sweden

China University of Mining and Technology, Beijing, China

KOMIR (Korea Mine Rehabilitation and Mineral Resources Corporation), Korea

Luossavaara-Kiirunavaara AB (LKAB), Luleå, Sweden

Nittetsu Mining Company, Ltd., Tokyo, Japan

Orica Mining Services Portugal, SA., Lisbon, Portugal

Phosagro, Kirovsk, Russia

Polymetal, St. Petersburg, Russia

RCC-Group, Ekaterinburg, Russia

Somincor - Sociedade Mineira de Neves Corvo, S.A., Castro Verde, Portugal

Uralkali, Berezniki, Russia

G RESEARCH ORGANIZATIONS

Beijing Anke Technology Co. Ltd., China

Bergab AB, Solna, Sweden

Besab AB Hisings Backa, Sweden

Central Research Institute of Electric Power Industry, Chiba, Japan

CETU (Centre d’Études des Tunnels), Lyon, France

Chalmers University of Technology, Göteborg, Sweden

Changjiang Survey Planning Design and Research, China

China Three Gorges Corporation, China

China University of Mining and Technology, Beijing, China

China University of Petroleum-Beijing, China

DynaFrax UG, Ltd., Germany

Fachhochschule Nordwestschweiz, Switzerland

Geobrugg Andina, Lima, Peru

Geoscience Research Laboratory, Co. Ltd., Yamato, Japan

Hubei University of Technology, China

Institute of Complex Development of Mineral Resources of the RAS, Moscow, Russia

Institute of Geology and Geophysics, Chinese Academy of Geological Sciences, China

Institute jsc „VNIMI“, St. Petersburg, Russia

Institute of Mining Siberian Branch of RAS, Novosibirsk, Russia

Institute of Mining, Far Eastern Branch of the RAS, Khabarovsk, Russia

Kajima Technical Research Institute, Tokyo, Japan

Korea Expressway Corporation Research Institute (KECRI), Hwaseong-si, Korea

LECM - Civil Engineering Laboratory of Macau, Macau, China

LLC Science Development Company „Mining Geomechanics, Russia

LNEC - Laboratório Nacional de Engenharia Civil, Lisbon, Portugal

Luleå University of Technology - LTU, Luleå, Sweden

Mining Institute KSC RAS, Apatity, Russia

Mining Institute Ural Branch of RAS, Siberia, Russia

National Institute of Natural Hazards, China

Nitro Consult Ab., Stockholm, Sweden

Norges Geologiske Undersøkelse, Trondheim, Norway

Norsk Forening for Fjellsprengn Teknikk, Oslo, Norway

Norsk Geoteknisk Forening, Oslo, Norway

NTNU Inst for Geologi og Bergteknikk, Trondheim, Norway

Perm National Research Polytechnic University, Perm, Russia

RCC-Group, Moscow, Russia

Research Institute of Experiment and Detection, Xinjiang Oilfield Company, Petro China, China

Rejlers Sverige AB, Sweden

RISE Research Institute of Sweden, Borås, Sweden

Royal Institute of Technology - KTH, Stokholm, Sweden

Saint-Petersburg Mining University, St. Petersburg, Russia

SC GEOSTUD SRL, Romania

Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering, Xauat, China

Shandong Innovative Material Technology Co. Ltd., China

Shijiazhuang Tiedao University, China

Sinopec Research Institute of Petroleum Engineering, China

SINTEF Teknologi og samfunn, Trondhein, Norway

Skanska AB, Solna, Sweden

Solexperts AG., Mönchaltorf, Switzerland

Stiftelsen Norges Geotekniske Institutt Oslo, Norway

Sweco AB, Stockholm, Sweden

Swedish Nuclear Fuel and Waste Management Co. – SKB, Stockholm, Sweden

WSP Sverige AB, Stockholm-Globen, Sweden

Zhejiang Society for Geotechnical Mechanics & Engineering, China

H UNIVERSITY

China University of Mining and Technology-Beijing, China

China University of Petroleum-Beijing, China

Hubei University of Technology, China

Shijiazhuang Tiedao University, Hebei, China

I GOVERNMENT DEPARTMENTS

Cerema, France

CETU (Centre d’Études des Tunnels), Lyon, France

China University of Mining and Technology-Beijing, China

LECM - Civil Engineering Laboratory of Macau, Macau, China

LNEC - Laboratório Nacional de Engenharia Civil, Lisbon, Portugal

Okumura Corporation, Ibaraki, Japan

Shandong University, China

Southwest Jiaotong University, China

J OTHER CORPORATE MEMBERS

ITOCHU Techno – Solutions Corporation, Tokyo, Japan

Kumagai Gumi Co. Ltd., Tokyo, Japan

Okumura Corporation, Ibaraki, Japan

Orica Mining Services Portugal, SA., Lisboa, Portugal

Phosagro, Moscow, Russia

WSP Finland Oy, Helsinki, Finland

MEMBERS

HOW TO JOIN THE ISRM

Individual members:

Individuals shall normally apply for membership of the ISRM through their National Group.

Corresponding members:

As some countries do not have a National Group, individuals may also apply for ISRM membership directly to the Secretariat.

Corporate members:

Companies shall apply for membership of the ISRM as corporate members directly to the Secretariat.

In some cases companies have also joined the ISRM as corporate members through their National Group.

National Groups:

For a national organisation to be recognised as a National Group, it is required to formally apply to the President through the Secretary-General for recognition according to the ISRM statutes. This shall be an organisation such as a society or a committee that represents Rock Mechanics in that country, either solely concerned with Rock Mechanics, or as part of a broader field of scientific or engineering interest. Each country shall have no more than one National Group.

BENEFITS TO MEMBERS

Current benefits given to ISRM Individual and corresponding members are:

• ISRM Newsletter

• Access to the members area in the website (download of Suggested Methods and Reports, Rock Mechanics lectures, videos, slide collection, etc.)

• Right to participate in the ISRM Commissions

• Registration with a 20% discount in the ISRM Congress, International and Regional Symposia and Specialized Conferences

• Personal subscription to the International Journal of Rock Mechanics and Mining Sciences at a discounted price (see details)

• Personal subscription to the Journal Rock Mechanics and Rock Engineering at a discounted price

• Free download of up to 100 papers per year from the ISRM Digital Library at OnePetro: www. onepetro.org

• Discount on purchases of CRC Press books: 40% discount on books in the ISRM Book Series; 30% discount on all other CRC Press books

Current benefits given to ISRM corporate members are:

• Being listed in the ISRM website, with a link to the company’s website

• Being listed in the ISRM News Journal

• Access to the members area in the ISRM website

• ISRM Newsletter

• 1 copy of the ISRM News Journal

• 1 registration with a 20% discount as ISRM member in the ISRM Congress, International and Regional Symposia and Specialized Conferences

• Free download of up to 250 papers per year from the ISRM Digital Library at OnePetro: www.onepetro.org.

ISRM

International Society for Rock Mechanics and Rock Engineering

ISRM Board

President

Vice-President for Africa

Vice-President for Asia

Vice-President for Australasia

Vice-President for Europe

Vice-President for Latin America

Vice-President for North America

Vice-President at Large

Secretary-General

Prof. Seokwon Jeon

Dr. Jannie Maritz

Prof. Ki-Bok Min

Dr. Qianbing Zhang

Dr. Muriel Gasc-Barbier

Dr. Esteban Hormazabal

Prof. Martin Grenon

Prof. Milorad Jovanovski

Prof. Kiyoshi Kishida

Dr. Fengshou Zhang

Dr. Luís Lamas

Secretariat

Ajanta Cave 26, Maharastra, India

ISRM News Journal 2024

NEWS J URNAL

ISRM

NEWS J URNAL

ISRM

EDITORS

LETTER FROM THE EDITORS

LAGER 2026

NAU MAI, HAERE MAI – WELCOME!

FOCUS TOPICS

THE 2023-2027 ISRM BOARD

SEOKWON JEON KOREA

QIANBING ZHANG AUSTRALIA

MARTIN GRENON CANADA

JAPAN

MARITZ SOUTH AFRICA

MURIEL GASC-BARBIER FRANCE

MILORAD JOVANOVSKI NORTH MACEDONIA

LUÍS LAMAS PORTUGAL

CHILE

FENGSHOU ZHANG CHINA

PRESIDENT'S MESSAGE

ISRM BOARD ACTIVITIES

ISRM INTERIM BOARD MEETING 2024

San José, Costa Rica

ISRM BOARD AND COUNCIL MEETINGS 2024

New Delhi, India

National Groups

NEWSLETTER

ISRM YOUTUBE CHANNEL

12. ISRM ONLINE LECTURES

13. CORRESPONDENCE AND BUSINESS ACTIVITIES OF THE SOCIETY

14. SUPPORT AFFORDED

15. FINAL REMARKS

MEMBERSHIP IN OCTOBER 2024

ROCHA MEDAL 2027

2024

THE 2024 ISRM YEAR EVENTS

ONLINE LECTURE SERIES

ISRM COMMISSIONS

ARTIFICIAL INTELLIGENCE IN ROCK MECHANICS AND ROCK ENGINEERING

BEYOND LIMITS: ROCKS IN THE FACE OF EXTREME CONDITIONS

BIO-ROCK MECHANICS

EARTHQUAKE MOTIONS IN ROCK ENGINEERING

ESTIMATION OF ROCK MASS STRENGTH AND DEFORMABILITY

MECHANICS OF ANCIENT ROCK STRUCTURES

RISKS AND RELIABILITY IN ROCK SLOPE ENGINEERING

ROCK WEATHERING AND EROSION

ULTRADEEP ROCK MASS MECHANICS AND ENGINEERING

AWARDS

ROCHA MEDAL

FRANKLIN LECTURE

JOHN HUDSON ROCK ENGINEERING AWARD

YOUNG ROCK ENGINEER AWARD

SCIENCE ACHIEVEMENT AWARD

5TH ISRM EUROPEAN ROCK MECHANICS DEBATE

6TH ISRM EUROPEAN ROCK MECHANICS DEBATE

HOEK-BROWN FAILURE CRITERION

ISRM YOUNG MEMBERS’ SEMINAR

NEW NATIONAL GROUPS

NEW VIDEOS OF ISRM

SUGGESTED METHODS

IN MEMORY OF

ISRM TRIBUTE TO DR. EVERT HOEK

ISRM SCIENTIFIC FAREWELL TO DR. EVERT HOEK

IN MEMORY OF

ISRM MEMBER’S VIEWS

FEMALE AND MOTHER IN AN ENGINEERING ENVIRONMENT

FORTHCOMING

ISRM SPONSORED CONFERENCES

2027

REPORTS OF ISRM CONFERENCES

2024 ISRM INTERNATIONAL SYMPOSIUM AND ARMS13

EUROCK 2024

ISL2024

5TH ICITG

VIETROCK 2024

1ST ISRM COMMISSION CONFERENCE

ISRM TECHNICAL OVERSIGHT COMMITTEE 2024

REPORT