Geomechanics and Tunnelling 01/2016 free sample copy

1 Volume 9 February 2016 ISSN 1865-7362

Geomechanics and Tunnelling Geomechanik und Tunnelbau

State of the art in geological mapping

- InSAR monitoring of ground movements - Tunnel monitoring in urban environments - Tunnel discontinuity mapping - Continuous real-time slope monitoring - 3D images for geological mapping - Data acquisition and 3D structural modelling Ă–STERREICHISCHE GESELLSCHAFT FĂœR GEOMECHANIK

Recommendations in Geotechnical Engineering

Ed.: Deutsche Gesellschaft für Geotechnik e.V. Recommendations on Excavations 3. Edition 2013. 324 pages. € 79,–* ISBN 978-3-433-03036-3 Also available as

For the new 3rd edition, all the recommendations have been completely revised and brought into line with the new generation of codes (EC 7 and DIN 1054), which will become valid soon. The book thus supersedes the 2nd edition from 2008.

Ed.: Deutsche Gesellschaft für Geotechnik e.V. Recommendations on Piling (EA Pfähle) 2013. 496 pages. € 109,–* ISBN 978-3-433-03018-9 Also available as

This handbook provides a complete overview of pile systems and their application and production. It shows their analysis based on the new safety concept providing numerous examples for single piles, pile grids and groups.

These recommendations are considered rules of engineering.

Ed.: Deutsche Gesellschaft für Geotechnik e.V. Recommendations for Design and Analysis of Earth Structures using Geosynthetic Reinforcements – EBGEO 2011. 316 pages. € 89,90* ISBN 978-3-433-02983-1 Also available as

The Recommendations deal with analysis principles and the applications of geosynthetics used for reinforcement purposes in a range of foundation systems, ground improvement measures, highways engineering projects, in slopes and retaining structures, and in landfill engineering.

Ed.: HTG Recommendations of the Committee for Waterfront Structures Harbours and Waterways EAU 2012 2015. 676 pages. € 129,–* ISBN 978-3-433-03110-0 Also available as

The “EAU 2012” takes into account the new generation of the Eurocodes. The recommendations apply to the planning, design, specification, tender procedure, construction and monitoring, as well as the handover of and cost accounting for port and waterway systems.

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Content

After about four years of construction, the Gemeinschaftskraftwerk Inn (GKI) on the upper River Inn should start generation in 2018 and produce more than 400 GWh of electricity from hydropower. With the exception of the headrace tunnel, adits, access tunnel and launching cuts are being excavated by drill and blast. For these conventional tunnel drives, DSI Österreich supplied the complete palette of support materials.

Nach rund vier Jahren Bauzeit soll das Gemeinschaftskraftwerk Inn (GKI) am Oberen Inn im Jahr 2018 ans Netz gehen und über 400 GWh Strom aus Wasserkraft liefern. Mit Ausnahme des Triebwasserstollen, entstehen Fensterstollen, Zugangsstollen und Anfahrbereiche im Sprengvortrieb. Für die konventionellen Vortriebe sowie für den Bau des Schrägschachts lieferte DSI Österreich die komplette Palette an benötigten Stützmitteln.

Geomechanics and Tunnelling 1 Volume 9 February 2016 • No 1 ISSN 1865-7362 (print) ISSN 1865-7389 (online)

Editorial 2

D. Scott Kieffer State of the art in geological mapping

Topics 15

Giovanni Barla, Andrea Tamburini, Sara Del Conte, Chiara Giannico InSAR monitoring of tunnel induced ground movements

23

Klaus Rabensteiner, Klaus Chmelina Tunnel monitoring in urban environments

29

Giovanni Barla, Francesco Antolini, Giovanni Gigli 3D laser scanner and thermography for tunnel discontinuity mapping

37

D. Scott Kieffer, Gerald Valentin, Klaus Unterberger Continuous real-time slope monitoring of the Ingelsberg in Bad Hofgastein, Austria

45

Andreas Gaich, Gerald Pischinger 3D images for digital geological mapping

52

Johannes Horner, Andrés Naranjo, Jonas Weil Digital data acquisition and 3D structural modelling for mining and civil engineering – the La Colosa gold mining project, Colombia

Rubrics 4 11 58 60 61

News People Product Information Site Report Diary of Events

Editor ÖSTERREICHISCHE GESELLSCHAFT FÜR GEOMECHANIK

http://wileyonlinelibrary.com/journal/geot

www.ernst-und-sohn.de/geomechanics-and-tunnelling

Bautechnik 81 (2004), Heft 1

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Editorial

State of the art in geological mapping Over the past decade significant technological advancements have been made in remote measurement and digital data acquisition technologies, and the implications for geomechanical characterization and monitoring are manifold. Some of the most important recent advancements in the context of geomechanics include 3D Light Detection and Ranging (LiDAR) for site characterization and change detection, Interferometric Synthetic Aperture Radar (InSAR) surveys for regional to local displacement monitoring, interactive gigapixel panoramic photography for unprecedented combinations of image scale and resolution, sophisticated algorithms invoking computer vision and photogrammetry, and mobile mapping systems combining cameras and LiDAR with INS/GPS sensors. The main advantage of these technologies is that georeferenced data with unprecedented resolution (spatial and temporal) and accuracy can be collected in a fraction of the time required for traditional survey methods.

Furthermore, the data processing workflow is auditable and the results are provided in the form of a comprehensive permanent archive.

Manuscripts in the current issue deal with several remote measurement technologies and illustrate their broad spectrum of application in geomechanics. These include satellite-based InSAR surveys to assess ground deformations at two tunnel construction sites in Italy, and geomechanical mapping of tunnels using 3D LiDAR combined with thermography. Results of the first long-term ground-based InSAR monitoring performed in Austria are reported in conjunction with the Ingelsberg landslide in Bad Hofgastein, and photogrammetric documentation for the Gleinalmtunnel in Styria is described. Digital data acquisition techniques and 3D structural geologic visualization in civil and mining engineering are illustrated with a case study of the La Colosa Gold Mining Project in Columbia, and a technical note on state-of-the-art tunnel monitoring in urban environments is included.

Scott Kieffer

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Š 2016 Ernst & Sohn Verlag fßr Architektur und technische Wissenschaften GmbH & Co. KG, Berlin ¡ Geomechanics and Tunnelling 9 (2016), No. 1

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News Main breakthrough in the Ceneri Base Tunnel On 21 January 2016, the main breakthrough took place in the west bore of the Ceneri Base Tunnel. About 700 m from the north portal in Camorino, more than 1,000 people involved in the project along with honorary guests followed the last blast in the west bore of the Ceneri Base Tunnel. The breakthrough was located with great precision, with a sideways deviation of 2 cm, and 1 cm in level.

Like the Gotthard Base Tunnel, the approx. 15.4 km long Ceneri Base Tunnel consists of two single-track running tunnels linked every 325 m by a cross passage about 40 m long. Due to the complex geology, the Ceneri Base Tunnel was excavated completely by drill and blast. The maximum rock overburden is 900 m, and the least just a few metres. The excavation was mostly carried out through the intermediate starting point at Sigirino in both directions.

Drives also came from the other direction from the Vigana and Vezia portals in order to save construction time and minimise costs. The first preliminary works took place as long ago as 1997 with the 3.1 km long investigation tunnel, and in 2008 a tunnel boring machine bored a 2.3 km long adit. At the end of this adit are two underground caverns, which have been the starting

Main breakthrough in the Ceneri Base Tunnel (photo: AlpTransit) Hauptdurchschlag im Ceneri-Basistunnel (Foto: AlpTransit)

points for the main drives to the south and north since 2010.

In the coming months, the lining of the tunnel will be progressed. By the end of 2016, all tunnels should be completely lined and completely concreted.

Then will follow the installation of the mechanical and electromechanical systems such as doors, ventilation and ser-

vices. The installation of railway equipment will start in summer 2017. This includes track, overhead, traction power and tunnel power, calling, telecommunications and radio systems, safety and automation systems and control technology. The Ceneri Base Tunnel should open for service in December 2020.

Hauptdurchschlag im Ceneri-Basistunnel Am 21. Januar 2016 fand in der Weströhre des Ceneri-Basistunnels der Hauptdurchschlag statt. Rund 700 m vom Nordportal in Camorino entfernt verfolgten mehr als 1.000 Projektbeteiligte zusammen mit den Ehrengästen die letzte Sprengung in der Weströhre des Ceneri-Basistunnels. Der Durchschlag erfolgte mit hoher Genauigkeit: Seitlich betrug die Abweichung 2 cm, in der Höhe 1 cm.

Wie der Gotthard-Basistunnel besteht der 15,4 km lange Ceneri-Basistunnel aus zwei Einspurröhren, die alle 325 m mit einem rund 40 m langen Querschlag verbunden sind. Der Ceneri-Basistunnel wurde aufgrund der komplexen Geologie ausschließlich im Sprengvortrieb ausgebrochen. Die maximale Felsüber-

lagerung beträgt bis zu 900 m, die geringste nur wenige Meter. Der Vortrieb erfolgte überwiegend vom Zwischenangriff Sigirino aus in beide Richtungen.

Von den Portalen Vigana und Vezia wurden Gegenvortriebe ausgeführt, um Bauzeit und Kosten zu minimieren. Erste Vorarbeiten erfolgten bereits 1997 mit dem 3,1 km langen Erkundungsstollen.

2008 brach eine Tunnelbohrmaschine einen 2,3 km langen Fensterstollen aus.

Am Ende dieses Stollens befinden sich zwei unterirdische Kavernen, die seit 2010 Ausgangspunkt für die Hauptvortriebe Richtung Süden und Norden waren.

In den kommenden Monaten wird der Innenausbau des Tunnels weiter vorangetrieben. Bis Ende 2016 werden

alle Röhren und Stollen ausgekleidet und fertig betoniert sein. Anschließend erfolgt die Installation der mechanischen und elektromechanischen Anlagen wie Türen, Tore oder Lüftungsund Haustechnikanlagen. Im Sommer 2017 beginnt der Einbau der Bahntechnik. Die bahntechnischen Installationen umfassen die Fahrbahn, Fahrleitung, Bahnstrom- und Stromversorgung, Kabel-, Telecom- und Funkanlagen, Sicherungs- und Automatisationssysteme sowie die Leittechnik. Die Inbetriebnahme des Ceneri-Basistunnels erfolgt voraussichtlich im Dezember 2020.

First TBM breakthrough in Norway for 20 years On 10 December 2015, the mechanised boring of the 7.4 km long headwater tunnel for the Røssåga hydropower project in Norway was completed – the first breakthrough of a TBM in Norway for a

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Geomechanics and Tunnelling 9 (2016), No. 1

good 20 years. The geological conditions were challenging; the Robbins hard rock machine with a bored diameter of 7.2 m passed through extremely hard rock with a high quartz content

and uniaxial compression strengths of up to 300 MPa, and also softer limestones with karst phenomena and water ingress. Despite the geological challenges, the machine achieved peak ad-

News vance rates of up to 250 m/week, or 54 m/d, with an average advance rate of 180 to 200 m/week.

The hard and abrasive rock demanded both the adjustment of the machine parameters to the geology, the tool wear and the vibration of the machine and also adjustment of the disc cutters themselves. The time for disc changing could indeed be reduced to less than ten minutes per disc but the frequent changing required a change to the disc cutters.

Robbins developed special cutting rings for the discs, which were adapted to suit the particular properties of the rock and its extreme hardness. This considerably lengthened the lifetime of the discs.

The Robbins TBM started in January 2014 after the first assembly on site (Onsite First Time Assembly – OFTA) and was designed for hard rock conditions from the start. Measured boring parameters were used for the analysis of the rock mass conditions while the machine bored, and systematic probe drilling was also carried out. After the completion of the tunnel drive, the client Statkraft has to prepare for the commissioning of the headwater tunnel and intends to fill it for the first time in early 2016.

The crew of the contractor Leonhard Nilsen & Sønner (LNS) celebrate together with the Robbins crew Norway’s first TBM breakthrough for a good 20 years on the Røssåga hydropower project (photo: LNS) Die Mannschaft der Baufirma Leonhard Nilsen & Sønner (LNS) feiert zusammen mit Robbins Crew Norwegens ersten TBM Durchbruch nach gut 20 Jahren beim Wasserkraftprojekt Røssåga (Foto: LNS)

Erster TBM-Durchschlag in Norwegen seit 20 Jahren Am 10. Dezember 2015 wurde der maschinelle Vortrieb des 7,4 km langen Triebwasserstollens für das Wasserkraftprojekt Røssåga in Norwegen beendet – es war der erste Durchbruch einer TBM in Norwegen seit gut 20 Jahren. Die geologischen Verhältnisse waren anspruchsvoll; die Robbins Hartgesteinsmaschine mit einem Bohrdurchmesser von 7,2 m durchfuhr extrem harten, quarzreichen Fels mit einaxialen Druckfestigkeiten bis zu 300 MPa und weichere Kalksteine mit Karsterscheinungen und Wasserzutritten. Trotz der geologischen Herausforderungen erreichte die Maschine mit einem Bohrdurchmesser von 7,2 m Spitzenvortriebsleistungen von bis zu 250 m/Woche bzw. 54 m/d bei einer mittleren Vortriebsgeschwindigkeit von 180 bis 200 m /Woche.

Der harte und abrasive Fels erforderte sowohl die Abstimmung der Fahrparameter auf die Geologie, den Werkzeugverschleiß und die Vibrationen der Maschine als auch eine Anpassung der Diskenmeißel selbst. Die Zeiten für einen Meißelwechsel konnten zwar auf unter zehn Minuten pro Meißel gesenkt werden, die häufigen Wechsel erforderten aber eine Überarbeitung der Schneiddisken. Robbins entwickelte spezielle Schneidringe für die Disken, die auf die besonderen Eigenschaften des Gesteins und die extreme Härte angepasst waren.

Damit konnte die Standzeit der Disken deutlich erhöht werden.

Die Robbins TBM startete im Januar 2014 nach der Erstmontage auf der Baustelle (Onsite First Time Assembly – OFTA) und war von Anfang an für die Hartgesteinsverhältnisse konzipiert. Zur Analyse der Gebirgsverhältnisse vor der

TBM wurden die während des Bohrens gemessenen Bohrparameter verwendet.

Zusätzlich wurden systematisch Vorauserkundungsbohrungen abgeteuft. Nach Abschluss des Vortriebs bereitet der Bauherr Statkraft die Inbetriebnahme des Triebwasserstollens vor und will ihn im Frühjahr 2016 zum ersten Mal befüllen.

The Robbins hard rock TBM started in January 2014 (photo: Statkraft) Die Robbins Hartgesteins-TBM wurde im Januar 2014 angefahren (Foto: Statkraft)

Geomechanics and Tunnelling 9 (2016), No. 1

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News Semmering Base Tunnel: start of tunnelling in Lower Austria

Contracts of the Semmering Base Tunnel (graphic: ÖBB Infrastruktur AG) Baulose des Semmering-Basistunnels (Grafik: ÖBB Infrastruktur AG)

Three years after groundbreaking for the overall Semmering Base Tunnel project, tunnelling started on 23 November 2016 in Gloggnitz. The tunnel will be excavated conventionally with excavator and blasting towards the Göstriz portal. The “Tunnel Gloggnitz” section in Lower Austria is a part more than 7 km long of the Semmering Base Tunnel with a total length of 27 km. Since the groundbreaking in 2012, two new rail bridges have been built in Gloggnitz to enable access

to the tunnel portal during the construction period. These already permit the route of the future railway line to the tunnel to be recognised. In addition to the advances from the tunnel portal at Gloggnitz, a complex system of access tunnels and shafts is being constructed at the intermediate starting point in Göstritz, from where the tunnel is being constructed towards Gloggnitz and Mürzzuschlag.

The Semmering Base Tunnel is divided into three large tunnel sections. The central Fröschnitzgraben section has been under construction since 2014, and the last Grautschenhof section should be started in 2016. The Tunnel Gloggnitz contract is being constructed by a joint venture of the companies Implenia, Hochtief Infrastructure and Thyssen Schachtbau; construction start was summer 2015.

Semmering-Basistunnel: Start für Tunnelbau von niederösterreichischer Seite Drei Jahre nach dem Spatenstich für das Gesamtprojekt Semmering-Basistunnel startete am 23. November 2016 in Gloggnitz der Tunnelbau. Der Tunnel Richtung Zwischenangriff Göstriz wird konventionell im Bagger- und Sprengvortrieb aufgefahren. Das niederösterreichische Teilstück „Tunnel Gloggnitz“ umfasst mehr als 7 km des insgesamt 27 km langen Semmering-Basistunnels.

Seit dem Spatenstich 2012 wurden in Gloggnitz zwei neue Eisenbahnbrücken

errichtet, die während der Bauarbeiten eine Zufahrt zum Tunnelportal ermöglichen und die zukünftige Eisenbahntrasse zum Tunnel erkennen lassen. Neben den Vortrieben vom Tunnelportal Gloggnitz aus entsteht am Zwischenangriff Göstritz ein komplexes System aus Zugangstunnel und Schächten, von dem aus der Tunnel in Richtung Gloggnitz und Mürzzuschlag gebaut wird.

Der Semmering-Basistunnel ist in insgesamt drei große Tunnelabschnitte unterteilt. Der mittlere Abschnitt Fröschnitzgraben ist seit 2014 in Bau, mit dem letzten Abschnitt Grautschenhof wird voraussichtlich im Frühjahr 2016 begonnen. Das Baulos Tunnel Gloggnitz wird von einer Arbeitsgemeinschaft aus Implenia, Hochtief Infrastructure und Thyssen Schachtbau erstellt; Baustart war im Sommer 2015.

Stellingen noise protection tunnel awarded A joint venture of the companies Hochtief Infrastructure and Franki Grundbau won the award in January 2016 for the construction of the Stellingen Tunnel in Hamburg. The total volume for the joint venture is about 154 m.

Euro. The tunnel is 900 m long and is being built as a noise protection structure as part of the improvement of the autobahn A7 between the Stellingen junction and the Hamburg-Nordwest in-

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Geomechanics and Tunnelling 9 (2016), No. 1

terchange. It is one of three noise protection tunnels, the “Hamburger Deckeln”, to be built in the course of the improvement.

The joint venture under the technical lead of Hochtief is building two tunnel sections in cut-and-cover, each with five lanes and a hard shoulder. The tunnel structure consists of an open, two-cell frame in cut-and-cover. The standard cross-section has a clear width of 22.5 m

or 22.6 m. The entry and exit slip roads for the Stellingen junction result in widened cross-sections with clear widths between 24.1 and 31 m. Both tunnel sections have four lanes, a weaving lane, hard shoulder and an emergency footpath. Due to the wide spans and the use, the tunnel spans are being constructed of prestressed concrete.

News Lärmschutztunnel Stellingen vergeben Eine Arbeitsgemeinschaft aus den Unternehmen Hochtief Infrastructure und Franki Grundbau hat im Januar 2016 den Auftrag zum Bau des Tunnels Stellingen in Hamburg erhalten. Das Gesamtauftragsvolumen für die Arbeitsgemeinschaft beträgt ca. 154 Mio. Euro. Der ca. 900 m lange Tunnel wird im Zuge des Ausbaus der A7 zwischen der Anschlussstelle Stellingen und dem Autobahndreieck Hamburg-Nordwest als lärmminderndes Bauwerk errichtet.

Er ist einer von drei Lärmschutztunneln, den „Hamburger Deckeln“, die im Zuge des Ausbaus entstehen.

Die Arbeitsgemeinschaft unter technischer Federführung von Hochtief baut zwei Tunnelröhren in offener Bauweise mit jeweils fünf Fahrspuren und einem Standstreifen. Das Tunnelbauwerk besteht aus einem nach unten offenen, zweizelligen Rahmen in offener Bauweise. Im Regelquerschnitt beträgt die lichte Weite 22,5 m bzw. 22,6 m. Die Einfahr- bzw. Ausfahrstreifen für den Anschluss Stellingen führen zu Querschnittsaufweitungen mit lichten Weiten zwischen 24,1 und 31 m. In beiden Röhren sind vier Fahrstreifen, ein Verflechtungsstreifen, Seitenstreifen und Notgehwege angeordnet. Wegen der großen Spannweiten sowie der Nutzung wird die Tunneldecke in Spannbeton ausgebildet.

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Asfinag awards the second bore of the Perjen Tunnel In February 2016, the new construction of the almost 3 km long Perjen Tunnel on the S16 Arlberg Schnellstraße will start. The construction contract has been awarded by Asfinag to a joint venture of Marti GmbH from Austria and Marti Tunnelbau AG from Switzerland. The contract volume is about 61 m. Euro. Asfinag is investing altogether 130 m. Euro in the new construction of the second bore and the refurbishment of the original bore. All works should be completed by the end of 2019 – then there will be two bores available, each with two lanes for 14,000 vehicles daily. The necessary preparatory works with the new construction of the Sanna Bridge were completed on schedule at the end of 2015.

Engineering association for work at heights

Asfinag vergibt zweite Röhre des Perjentunnels Im Februar 2016 startete der Neubau der knapp 3 km langen neuen Röhre des Perjentunnels auf der S16 Arlberg Schnellstraße. Den Zuschlag für die Bauarbeiten erteilte die Asfinag an die Arbeitsgemeinschaft Marti GmbH aus Österreich und die Marti Tunnelbau AG aus der Schweiz. Das Auftragsvolumen beträgt rund 61 Mio. Euro. Insgesamt investiert die Asfinag 130 Mio. Euro in den Neubau der zweiten Röhre und in die Sanierung der Bestandsröhre. Ende 2019 sollen alle Arbeiten abgeschlossen sein – dann stehen zwei Röhren mit jeweils zwei Fahrspuren für mehr Sicherheit für täglich 14.000 Verkehrsteilnehmer zur Verfügung. Die notwendigen Vorarbeiten mit dem Neubau der Sannabrücke wurden plangemäß Ende 2015 abgeschlossen.

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Geomechanics and Tunnelling 9 (2016), No. 1

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News Züblin to extend the largest copper mine in the world Züblin International has won a followup order from the Chilean mining company Codelco, the largest producer of copper in the world, for the extension of the El Teniente mine in Rancagua – 80 km south of the capital Santiago de

Chile. Züblin has already performed extensive tunnelling work at the mine since March 2014. With the new contract worth 100 m. Euro, Züblin will become one of the leading firms in underground construction in Chile. The ex-

tension will prolong the life of the mine, which has been in operation since 1904, by about 50 years. At the moment, about 400,000 t of fine copper are produced in El Teniente annually. The mine operates by block caving.

Züblin erweitert weltgrößtes Kupferbergwerk Züblin International hat von der chilenischen Bergwerksgesellschaft Codelco, dem weltweit größten Kupferproduzenten, einen Folgeauftrag für die Erweiterung des Bergwerks El Teniente in Rancagua – 80 km südlich der Hauptstadt Santiago de Chile – erhalten. Züblin

führte bereits seit März 2014 umfangreiche Tunnelbau-Arbeiten in dem Bergwerk durch. Durch den neuen Auftrag in Höhe von 100 Mio. Euro steigt Züblin in Chile zu den führenden Baufirmen im Untertagebau auf. Der Ausbau wird die Lebensdauer des Bergwerks, das be-

reits seit 1904 in Betrieb ist, um 50 Jahre erhöhen. Zurzeit werden in El Teniente jährlich rund 400.000 t Feinkupfer erzeugt. Die Erzgewinnung erfolgt im Blockbruchbau.

German Railways awards the Albvorland Tunnel The DB Projekt Stuttgart-Ulm GmbH awarded the contract for the 8,176 m long Albvorland Tunnel on the new line from Wendlingen to Ulm to the Swiss construction and construction services company Implenia on 18 December 2015. The contract volume is about 380 m. Euro. Eight bidders took part in the European tendering process. This means that the last of the eight large

tunnels on the Stuttgart-Ulm rail project has now been awarded. In addition to the building of the Albvorland Tunnel, the contract also includes the construction of the two links of the new line between Stuttgart und Ulm to the existing Plochingen-Tübingen line. This is the Wendlinger Kurve including a new 494 m long tunnel for new trains on the line from Stuttgart to Tübingen. There

East portal of the Albvorland Tunnel in Wendlingen (graphic: DB AG) Ostportal des Albvorlandtunnels in Wendlingen (Grafik: DB AG)

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Geomechanics and Tunnelling 9 (2016), No. 1

is also a connection for goods trains on the route from Ulm to Plochingen including a 173 m long tunnel under the federal autobahn A8. The site facilities and preparatory works were already started at the beginning of 2016. The start of the main construction works is planned for summer 2016. Two tunnel boring machines are intended for the construction of the Albvorland Tunnel.

News Bahn vergibt Albvorlandtunnel Die DB Projekt Stuttgart-Ulm GmbH hat am 18. Dezember 2015 den Bau des 8.176 m langen Albvorlandtunnels auf der Neubaustrecke Wendlingen-Ulm an das schweizerische Bau- und Baudienstleistungsunternehmen Implenia vergeben. Der Auftragswert beträgt rund 380 Mio. Euro. An dem Teilnahmewettbewerb zur europaweiten Ausschreibung hatten sich acht Bieter beteiligt. Damit ist der letzte der acht großen Tunnel des

Bahnprojekts Stuttgart-Ulm vergeben.

Neben dem Bau des Albvorlandtunnels umfasst der Auftrag auch die Herstellung der beiden Anschlüsse der Neubaustrecke zwischen Stuttgart und Ulm an die bestehende Bahnstrecke PlochingenTübingen. Dies ist zum einen die Wendlinger Kurve einschließlich eines 494 m langen Tunnels für neue Zugfahrten in der Verbindung Stuttgart-Tübingen. Zum anderen wird auch die Güterzuganbin-

dung für Züge der Verbindung UlmPlochingen einschließlich eines 173 m langen Tunnels unter der Bundesautobahn A8 gebaut. Die Baustelleneinrichtungen sowie bauvorbereitende Arbeiten beginnen bereits Anfang 2016. Der Beginn der Hauptbaumaßnahmen ist für Sommer 2016 vorgesehen. Für den Bau des Albvorlandtunnels ist der Einsatz von zwei Tunnelvortriebsmaschinen vorgesehen.

Works acceptance for the TBM for the Rastatt Tunnel After extensive inspections and tests by the Tunnel Rastatt joint venture consisting of the companies Ed. Züblin AG (technical lead) and Hochtief Solutions AG (commercial lead), the first of two tunnel boring machines for the Rastatt tunnel project was accepted in December 2015 at Herrenknecht in Schwanau.

The 93 m long mixshield machine with a weight of 2,300 t and a shield diameter of 10.94 m will now be dismantled for transport to the launching cut near Ötigheim, where the machine should start work at the end of May 2016 after being reassembled. The second machine should follow with a time delay of about four months. The machines will each bore a section of about 3,700 m under the built-up area of Rastatt, through groundwater and loose rock. They will have to pass beneath the existing Rheintalbahn railway line as well as the small Rivers Murg and Federbach.

The altogether 4,270 m long Rastatt Tunnel is intended to carry a large part of the goods and long-distance traffic and thus relieve the nuisance of heavy rail traffic for the local inhabitants. As a section of the line from Karlsruhe to

The mixshield S-953 for the Rastatt Tunnel before factory approval (photo: Herrenknecht AG) Der Mixschild S-953 für den Tunnel Rastatt vor der Werksabnahme (Foto: Herrenknecht AG)

Basel, it is part of the TEN (Trans-European Network) corridor from Rotterdam to Genoa. Another two machines are also currently being built at the Schwanau

works for the improvement of the section of the corridor from Milan to Genoa.

Werksabnahme der TBM für Tunnel Rastatt Nach umfangreichen Besichtigungen und Tests durch die Arbeitsgemeinschaft Tunnel Rastatt, bestehend aus den Unternehmen Ed. Züblin AG (technische Federführung) und Hochtief Solutions AG (kaufmännische Federführung), ist im Dezember 2015 die erste von zwei Tunnelbohrmaschinen für das Projekt Tunnel Rastatt bei Herrenknecht in Schwanau abgenommen worden. Der 93 m lange und 2.300 t schwere Mixschild mit einem Schilddurchmesser von 10,94 m wird im Anschluss

demontiert und zur Startbaugrube nach Ötigheim transportiert. Dort beginnt die Maschine nach ihrem Wiederaufbau voraussichtlich Ende Mai 2016 den Vortrieb. Die zweite Maschine soll zeitversetzt vier Monate später folgen. Vor den beiden Tunnelbohrmaschinen liegt eine Strecke von je rund 3.700 m unter dem Stadtgebiet Rastatt durch Grundwasser und Lockergestein. Dabei sind die bestehende Rheintalbahn sowie die Gewässer Murg und Federbach zu unterqueren.

Der insgesamt 4.270 m lange Rastatt Tunnel soll den Großteil des Güter- und Fernverkehrs aufnehmen und so die Anwohnerinnen und Anwohner deutlich vom Schienenverkehr entlasten. Als Abschnitt der Ausbau- und Neubaustrecke Karlsruhe-Basel ist er Bestandteil des TEN-Korridors (Transeuropäische Netze) von Rotterdam bis Genua. Für den Ausbau der Teilstrecke Mailand bis Genua des Korridors werden aktuell ebenfalls zwei Maschinen im Werk in Schwanau gefertigt.

Geomechanics and Tunnelling 9 (2016), No. 1

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News Route planning for alignment selection commissioned for the Brenner north approach In November 2015, ÖBB Infrastruktur AG and DB Netz AG commissioned the consultants ILF Consulting Engineers, Schüßler-Plan Ingenieurgesellschaft mbH and Baader Konzept GmbH with the cross-border production of a route recommendation for the optimal align-

ment of a 3rd and 4th track (new line NBS) for the approach route to the Brenner Base Tunnel. The design area for the Brenner north approach includes in the southern section the future line from the junction at Schaftenau in the Tyrol to a new junction “Deutsches Inn-

tal” south of Rosenheim. North and east of the new “Deutsches Inntal” junction, possible links to the existing rail network of DB AG in the directions of Munich, Mühldorf and Salzburg are to be investigated.

Streckenplanung zur Trassenauswahl für den Brenner-Nordzulauf beauftragt Im November 2015 haben die von der ÖBB Infrastruktur AG und der DB Netz AG die Ingenieurgesellschaften ILF Consulting Engineers, Schüßler-Plan Ingenieurgesellschaft mbH und Baader Konzept GmbH mit der grenzüberschreitenden Erarbeitung einer Trassenempfehlung für die optimale Strecken-

führung eines 3. und 4. Gleises (Neubaustrecke NBS) für die Zulaufstrecke zum Brennerbasistunnel beauftragt. Der Planungsraum des Brenner-Nordzulaufs umfasst im Südabschnitt die künftige Strecke von der Verknüpfungsstelle Schaftenau in Tirol bis zu einer neuen Verknüpfungsstelle „Deutsches Inntal“

südlich von Rosenheim. Nördlich und östlich der neuen Verknüpfungsstelle „Deutsches Inntal“ sind die möglichen Anbindungen an das bestehende Schienennetz der DB AG in Richtung München, Mühldorf und Salzburg zu untersuchen.

Call for papers Call for papers – Themes for the next issues of Geomechanics and Tunnelling The table below shows the themes for the next issues of “Geomechanics and Tunnnelling”, selected by the editing team, and contributions are now being called for. All papers received will first be reviewed prior to publication. In view of the time required to complete this exercise, all contributions should be submitted at least four months before the publication date. Papers should be submitted online via http:// mc.manuscriptcentral.com/geot.

Site reports, technical reports and news items from the construction industry are of course also welcome.

Themen für die nächsten Ausgaben der „Geomechanics and Tunnelling“ Die Schwerpunktthemen für die nächsten Ausgaben der „Geomechanics and Tunnelling“ sind in der untenstehenden Tabelle zusammengefasst.

Das Redaktionsteam bittet um Beitragsvorschläge. Unter Berücksichtigung des Reviews sollten die Beiträge mindestens vier Monate vor dem Erscheinungstermin eingereicht werden. Beiträge sollten online eingereicht werden (http://mc.manuscriptcentral.com/ geot).

Darüber hinaus sind Baustellenreportagen, technische Berichte und Mitteilungen aus der Industrie jederzeit willkommen.

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Issue

Publication date

Topics

2/16

April 2016

Gotthard Base Tunnel Gotthard-Basistunnel

3/16

June 2016

Research activities in TBM tunnelling Forschungsaktivitäten beim Tunnelbau mit TBM

4/16

August 2016

Rock slopes – Landslides incl. examples from projects Felshänge – Erdrutsche inkl. Beispielen aus Projekten

5/16

October 2016

Geomechanics Colloquium Geomechanik Kolloquium

6/16

December 2016

Austrian Tunnelday 2016 Österreichischer Tunneltag 2016

People Obituary for Em. Univ. Professor Martin Fuchsberger

Martin Fuchsberger on the day of his 91st birthday celebration Martin Fuchsberger am Tag der Feier seines 91. Geburtstages

On 12 November 2015, Em. Univ. Prof.

Dipl.-Ing. Martin Fuchsberger M.Sc. died at his home in Hausmannstätten near Graz at the age of 92. He was laid to rest a few days later in the graveyard of the Pfarrkirche of Ebenau near Salzburg, attended by numerous of his family, friends, professional colleagues and the inhabitants of the neighbourhood.

Prof. Fuchsberger was born on 28 February 1924 in Ebenau and spent his childhood there. His later attendance at the Gymnasium, however, required commuting to the nearby Salzburg.

On his return from three years of military service, extending to the Russian front, he started a course in Civil Engineering at the Technische Hochschule Graz, which he completed in 1951 with the second state exam and a degree in engineering.

He gathered his first professional experience with a construction company

in Sweden and a consultant in Salzburg, before moving to the USA for four years in 1954. In the USA, he supplemented his degree with an M.Sc. and worked on soil mechanics projects with Prof. Jorj O. Osterberg at the Northwestern University, Evanston, and investigated the frost susceptibility of soils at the U.S. Army Corps of Engineers, Wilmette, in Chicago, Illinois.

Returning to Austria for personal reasons, Prof. Fuchsberger was first active on a self-employed basis working for Em. Prof. Dr. Otto Karl Fröhlich in Vienna and Dr. Christian Veder in Salzburg and was responsible during this time for slope support measures and deep foundations with the appropriate trial loading.

Then followed work with the Impresa di Costruzione Opere Specializzate (I.C.O.S.) in Milan from 1959 to 1962, including working on the Hyde Park Corner road tunnel in London. The work on this project resulted in his moving to London for another 20 years to the company ICOS Ltd., a specialised civil engineering company. With his specialist knowledge, it was only a matter of time before he was in charge of the company as general manager and director.

In 1982, he accepted an appointment as Professor for Soil Mechanics, Rock Mechanics and Foundation Engineering at the Technical University of Graz and continued this challenge with joy until his retirement as emeritus. For him, the link between theory and practice was an important matter in research and lecturing. He undertook research into the properties of bentonite suspensions and frozen soil, diaphragm walling technology, the use of compressed air in tunnelling and vibro-displacement densification in cohesive soils. The results achieved at the Institute under his leadership are documented in a ten year re-

port published in 1993 by the Institute of Soil Mechanics and Foundation Engineering.

The Christian Veder Colloquium, which was founded in 1985 by Prof.

Fuchsberger und Prof. Dr. Helmut F. Schweiger and repeated annually, raised interest far beyond Austria. About 400 professionals have regularly taken part in this specialist event in Graz in recent years. 2015 was the 30th repeat and once again, Prof. Fuchsberger did not miss the chance to hear about new findings in the field of Geotechnics.

The extensive knowledge of Prof.

Fuchsberger, combined with his conciliatory personality, led to an invitation by his successor in 1996 to take part as emeritus in a lecture tour of Rumania.

In the course of just a few years, five further lecture tours together followed at the Universitatea Politehnica, Timis¸oara and the Universitatea din Cluj-Napoca, the capitals of the Banat and Transylvania. His knowledge, concise diction and rhetorical ability always attracted students. Few university lecturers gain such respect.

Prof. Fuchsberger had a secret fondness for the English language area and especially London. This was shown by English terms appearing in his German speech, even during the lifetime of his wife Charlotte. This fondness is also illustrated by the fact that he made it possible for both his children to start their professional careers in London.

With the death of Martin Fuchsberger, a fulfilled life has come to an end. We remember an affectionate, warm-hearted and always interested friend and colleague and will always commemorate him with honour.

Roman Marte Wulf Schubert Stephan Semprich

Nachruf Em.Univ.-Professor Martin Fuchsberger Am 12. November 2015 ist Em.Univ.Prof. Dipl.-Ing. Martin Fuchsberger M.Sc. in seinem Heim in Hausmannstätten bei Graz im 92. Lebensjahr verstorben. Seine letzte Ruhe fand er wenige Tage später auf dem Friedhof der Pfarrkirche von Ebenau bei Salzburg unter großer Anteilnahme seiner Familie, Freunde, Fachkollegen und den Bewohnern der örtlichen Umgebung.

Prof. Fuchsberger ist am 28. Februar 1924 in Ebenau geboren und hat auch dort seine Jugend verbracht. Mit dem späteren Besuch des Gymnasiums wa-

ren allerdings regelmäßige Fahrten in das benachbarte Salzburg verbunden.

Nach Rückkehr aus einem dreijährigen, bis zur Ostfront reichenden Kriegseinsatz begann er das Studium des Bauingenieurwesens an der Technischen Hochschule Graz, das er 1951 mit der II. Staatsprüfung und dem Grad eines Diplom-Ingenieurs abschloss.

Anschließend sammelte er erste Berufserfahrungen bei einer Bauunternehmung in Schweden und einem Ingenieurbüro in Salzburg, bevor er 1954 für vier Jahre in die USA wechselte. Hier ergänzte er sein Studium mit dem Ab-

schluss zum M.Sc. und bearbeitete Forschungsprojekte der Bodenmechanik bei Prof. Jorj O. Osterberg an der Northwestern University, Evanston, und zur Frostempfindlichkeit von Böden beim U.S. Army Corps of Engineers, Wilmette, in Chicago, Illinois.

Aus familiären Gründen nach Österreich zurückgekehrt, war Prof. Fuchsberger zunächst als freier Mitarbeiter für Em.Prof. Dr. Otto Karl Fröhlich in Wien und Dr. Christian Veder in Salzburg tätig und bearbeitete in dieser Zeit Hangsanierungen und Tiefgründungen mit entsprechenden Probebelastungen.

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People Anschließend folgte von 1959 bis 1962 eine Tätigkeit bei der Impresa di Costruzione Opere Specializzate (I.C.O.S.) in Mailand, unter anderem für den Straßentunnel Hyde Park Corner in London. Diese Projektbearbeitung hatte zur Folge, dass er für weitere 20 Jahre nach London in die Firma ICOS Ltd., ein Bauunternehmen für den Spezialtiefbau, wechselte. Aufgrund seines Fachwissens dauerte es nur kurze Zeit, bis er das Unternehmen als General Manager und Direktor verantwortlich leitete.

Im Jahr 1982 ist er dem Ruf nach einem Ordentlichen Professor für Bodenmechanik, Felsmechanik und Grundbau an die Technische Universität Graz gefolgt und hat diese Herausforderung über elf Jahre bis zu seiner Emeritierung mit Freude ausgeübt. Dabei war ihm in Forschung und Lehre der Zusammenhang zwischen Theorie und Praxis ein wichtiges Anliegen. Im Bereich der Forschung hat er sich mit Fragen zu Eigenschaften von Bentonitsuspensionen und gefrorenem Boden, zur Schlitzwandtechnik, zum Einsatz von Druckluft im Tunnelbau, zur Tragfähigkeit von Tiefgrün-

dungselementen und zur Stopfverdichtung bindiger Böden auseinandergesetzt.

In einem 1993 vom Institut für Bodenmechanik und Grundbau herausgegebenen Zehn-Jahresbericht sind die unter seiner Leitung am Institut erarbeiteten Ergebnisse dokumentiert.

Ein weit über die österreichischen Grenzen hinausreichendes Echo hat das im Jahr 1985 von Prof. Fuchsberger und Prof. Dr. Helmut F. Schweiger gegründete und jährlich stattfindende Christian Veder Kolloquium gefunden. An dieser Grazer Fachveranstaltung haben in den letzten Jahren regelmäßig ca. 400 Fachkollegen teilgenommen. 2015 fand diese Tagung zum 30. Mal statt und wiederum ließ es sich Prof. Fuchsberger nicht nehmen, neue Erkenntnisse auf dem Gebiet der Geotechnik zu erfahren.

Das umfangreiche Wissen von Prof.

Fuchsberger, verbunden mit einer konzilianten Persönlichkeit, veranlasste seinen Nachfolger, ihn 1996 als Emeritus zur Teilnahme an einer Vorlesungsreise nach Rumänien einzuladen. Im Abstand von wenigen Jahren folgten weitere fünf gemeinsame Vorlesungsreisen zu der Universitatea Politehnica Timis¸oara und

der Universitatea din Cluj-Napoca und damit in die Hauptstädte des Banats und Siebenbürgens. Stets zogen sein Wissen, seine prägnante Ausdrucksweise und seine Rhetorik die Studierenden an. Eine größere Anerkennung ist einem Hochschullehrer nur selten vergönnt.

Eine heimliche Vorliebe von Prof.

Fuchsberger hat dem englischen Sprachraum und insbesondere der Stadt London gegolten. Das zeigte sich daran, dass bereits zu Lebzeiten seiner Frau Charlotte in seinen deutschen Redefluss häufiger englische Begriffe eingeflossen sind. Deutlich wird diese Zuneigung auch dadurch, dass er seinen beiden Kindern die Möglichkeit geboten hat, in dieser Stadt ihre beruflichen Karrieren zu beginnen.

Mit dem Tod von Martin Fuchsberger ist ein erfülltes Leben zu Ende gegangen. Wir erinnern uns an einen liebevollen, warmherzigen und stets interessierten Freund und Kollegen und werden seiner stets ehrenvoll gedenken.

ests, only engineering was in consideration and his final decision was to study civil engineering, although he has maintained an interest in other disciplines such as mechanical and electrical engineering until today. The course at the TU Graz with its very good theoretical education and practical experience during holiday placements at the Kops power station, the Felbertauern Tunnel, in England and Sweden provided the basis for his later successful career.

Graduation was followed by activity as an assistant from 1967 to 1973 at the Chair of Reinforced Concrete and Massive Construction at the TU Graz with Prof. Bauer, finally leading to a dissertation on the subject “Cantilever launching of dome shells in in-situ concrete”.

During this time in Graz, he decided to start a family. After marriage to Dagmar in 1967, the children Dagmar and Hanno were born in 1971 and 1972.

In 1973, Harald Lauffer started his career with Porr, where he worked all through his career and is still strongly connect after official retirement. His work on site led him, starting at the Tauern Tunnel (1973 to 1974, office work), to the Kölnbrein dam (1974 to 1978, deputy site manager) and then to Persia, where he undertook the challenging task of site manager at the

Minab dam (1976 to 1978). This was followed by the post of manager of the Teheran office (1978 to 1979), which had to be closed after the political changes in Iran in 1979. After his return to Vienna, he was appointed departmental manager for tunnel and power station construction (1979 to 1987) and then joined the boards of Porr International (1987 to 1998) and Porr Technobau und Umwelttechnik (1989 to 1992).

During this period, some important power station and tunnel projects were completed with the essential involvement of Harald Lauffer, the most noteworthy being: – Power station construction: Walgau tunnel with 6.25 m diameter, the largest TBM in Europe at the time.

Amlach inclined shaft, Inn power station at Oberaudorf-Ebbs.

– Tunnelling: Espenloh, Kaiserau, Hainbuch, Rengershausen, Kehrenberg and Mainzer tunnels for German Railways DB. Untersberg and Schattenburg Tunnels for Austrian Railways ÖBB. Säusenstein Tunnel and the Semmering pilot tunnel for the HL-AG.

Roman Marte Wulf Schubert Stephan Semprich

75th birthday of Harald Lauffer

Harald Lauffer

Dipl.-Ing. Dr.techn. Harald Lauffer was born on 20 December 1940 in Innsbruck as the second of four children.

The cosmopolitan family provided the four children an environment, in which they could develop their sporting and practical talents and also develop an interest in education and culture. Particularly the many discussions with his father, who had played a large part in power station construction for Tiwag, gave the young Harald an extensive overview of power station construction and influenced his later career.

After successfully completing his school certificate and ROA training in the army, a decision had to be made about a university course. With his inter-

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Geomechanics and Tunnelling 9 (2016), No. 1

From 1992 to his final retirement from Porr in 2010 Harald Lauffer undertook strategic tasks in tunnelling, concentrating on special tasks like technology

People management, work preparation and knowledge transfer. In this phase, he advised and supported employees on site logistics, technology development and other construction management issues.

Particularly the technological development of continuous (mechanised) tunnelling, innovative and influential ideas were implemented on the Wientalsammelkanal, Wienerwald Tunnel, H 3/4 and Finne Tunnel projects. The further development of shotcrete technology from the wet mix process with sprayed binder to the dry mix process was another important achievement

Harald Lauffer with his extensive technical understanding played an important role in the development of the applicable regulations for tunnelling. In the production of the Austrian standard ÖNORM B 2203-1 for cyclical tunnelling, the matrix system, dimensionless support measures and water obstructions all show his influence. He also played an important part in the production of ÖNORM B2203-2 for continuous tunnelling. His constructive collaboration was also estimated in the production of the ÖGG design guideline for continuous tunnelling and the ÖBV guidelines

for shotcrete and inner lining concrete as well as the Assessment Report for Shield Machines and Segments.

Meeting with Harald Lauffer has always been a special experience for us all, independent of age and professional experience, with his solution-oriented, ever critical discussions filled with new ideas.

I wish to express personal thanks for our collaboration of more than 30 years, always with open, constructive and very good discussions.

All the best on your 75th birthday!

heute, nach seinem offiziellen Ausscheiden, stark verbunden ist. Seine Baustelleneinsätze führten ihn, beginnend vom Tauerntunnel (1973 bis 1974, Innendienst) über die Kölnbreinsperre (1974 bis 1978, Bauleiterstv.) bis nach Persien, wo er die sehr anspruchsvolle Aufgabe des Bauleiters der Minabsperre (1976 bis 1978) übernahm. Es folgte die Geschäftsführung der Niederlassung Teheran (1978 bis 1979), die durch die politischen Veränderungen im Iran 1979 geschlossen werden musste. Nach seiner Rückkehr nach Wien wurden ihm neue Aufgaben in der Position des Abteilungsleiters für Tunnel- und Kraftwerksbau (1979 bis 1987) übertragen, daran schloss sich die Berufung in den Vorstand der Porr International (1987 bis 1998) und Porr Technobau und Umwelttechnik (1989 bis 1992) an.

In dieser Zeit werden im Kraftwerksund Tunnelbau bedeutende Projekte unter maßgeblicher Beteiligung von Harald Lauffer realisiert. Als markanteste sind dabei zu nennen: – Kraftwerksbau: Walgaustollen mit 6,25 m Durchmesser, damals die größte TBM europaweit. Schrägschacht Amlach, Innkraftwerk Oberaudorf-Ebbs.

– Tunnelbau: Espenloh-, Kaiserau-, Hainbuch-, Rengershausen-, Kehrenberg- und Mainzertunnel für die DB. Untersberg- und Schattenburgtunnel für die ÖBB. Säusensteintunnel und Pilotstollen Semmering für die HL-AG.

Technologieentwicklung und anderen beraten und unterstützt. Insbesondere zur Technologieentwicklung im kontinuierlichem Vortrieb wurden bei der erfolgreichen Umsetzung der Projekte Wientalsammelkanal, Wienerwaldtunnel, H 3/4 und Finnetunnel innovative Ideen eingebracht und wesentliche Akzente gesetzt. Die Weiterentwicklung der Spritzbetontechnologie vom Feuchtspritzverfahren mit Spritzbindemitteln bis zum Nassspritzverfahren war ein weiterer wichtiger Schwerpunkt.

Bei der Ausarbeitung der einschlägigen Regelwerke des Tunnelbaus hat Harald Lauffer mit seinem umfangreichen Fachwissen engagiert mitgewirkt.

Bei der Ausarbeitung der ÖNORM B 2203-1 für den zyklischen Vortrieb in den Versionen 1994 und 2001 tragen das Matrix-System, die dimensionslose Stützmittelzahl und die Wassererschwernisse seine Handschrift. Wesentliche Akzente konnte er bei der Erarbeitung der ÖNORM B2203-2 für den kontinuierlichen Vortrieb setzen. Seine konstruktive Mitarbeit wurde auch bei der Ausarbeitung der ÖGG-Planungsrichtlinie für den kontinuierlichen Vortrieb und bei den ÖBV-Richtlinien für Spritzbeton- und Innenschalenbeton sowie beim Sachstandsbericht Schildmaschinen und Tübbinge geschätzt.

Die Begegnung mit Harald Lauffer ist für uns alle, unabhängig vom jeweiligen Lebensalter bzw. der Berufserfahrung, mit seinem lösungsorientierten, immer kritischen und immer mit neuen Ideen gefüllten Gespräch ein besonderes Erlebnis.

Ich bedanke mich persönlich für die mehr als 30-jährige Zusammenarbeit und unser immer offenes, konstruktives und sehr gutes Gesprächsklima.

Alles Gute zum 75. Geburtstag!

Wolfgang Stipek

75 Jahre Harald Lauffer Dipl.-Ing. Dr.techn. Harald Lauffer wurde am 20. Dezember 1940 in Innsbruck als zweites von vier Kindern geboren.

Das weltoffene Elternhaus gab den vier Kindern ein Umfeld, in dem diese ihre sportlichen und handwerklichen Talente sowie ihre Interessen für Bildung und Kultur entwickeln konnten. Insbesondere die vielen Gespräche mit dem Vater, der den Kraftwerksausbau der Tiwag maßgeblich mitgestaltet hat, gaben dem jungen Harald einen umfassenden Einblick in den Kraftwerksausbau und prägten seinen weiteren Lebensweg.

Nach der erfolgreich bestandenen Matura und der ROA-Ausbildung beim Bundesheer war die Entscheidung über die Studienwahl zu treffen. Aufgrund der Interessenslage kam nur ein technisches Studium in Frage und nach reif licher Überlegung fiel die Entscheidung zugunsten des Bauingenieursstudiums.

Das Interesse für andere technische Disziplinen wie Maschinenbau, Elektrotechnik und andere blieb bis heute erhalten. Das Studium an der TU-Graz mit seiner sehr guten theoretischen Ausbildung und die praktische Erfahrung im Zuge der Ferialpraxen am Kraftwerk Kops, dem Felbertauerntunnel, in England und Schweden schufen die Basis für die spätere erfolgreiche berufliche Laufbahn.

Dem Studienabschluss folgte die Assistententätigkeit von 1967 bis 1973 an der Lehrkanzel für Stahlbeton und Massivbau an der TU-Graz bei Prof. Bauer, die ihren Abschluss in der Dissertation zum Thema „Der Freivorbau von Kuppelschalen in Ortbetonbauweise“ fand.

Während dieser Zeit in Graz fiel auch die Entscheidung, eine Familie zu gründen. Nach der Eheschließung mit Dagmar 1967 kamen die Kinder Dagmar und Hanno 1971 und 1972 zur Welt.

1973 startete Harald Lauffer seine berufliche Tätigkeit bei Porr der er sein gesamtes Berufsleben und auch noch

Von 1992 bis zum endgültigen Ausscheiden bei Porr 2010 übernahm Harald Lauffer strategische Aufgaben für den Tunnelbau, in denen Spezialaufgaben, wie Technologiemanagement, Arbeitsvorbereitung und Wissenstransfer die Schwerpunkte bildeten. In dieser Phase wurden die Mitarbeiter zu bauwirtschaftlichen Themen, Baustellenlogistik,

Wolfgang Stipek

Geomechanics and Tunnelling 9 (2016), No. 1

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People Retirement Professor Hans Georg Jodl

Hans Georg Jodl

Professor Jodl, chairman of the Institute of Interdisciplinary Construction Process Management at the Vienna University of Technology, retired as emeritus on 30 September 2015.

In his farewell lecture on 27 November 2015 in the Kuppelsaal of the TU Vienna, he offered a witty look back at his career and made suggestions for future developments in construction management and construction process technology. At the subsequent emeritus celebration, his achievements were honoured by the speakers in very personal speeches.

Prof. Jodl, born on 29 June 1947, grew up in the Vienna suburb of Mauer, attended the Bundesrealgymnasium in the Rosasgasse in the suburb of Meidling and then decided to study civil engi-

neering at the TU Vienna. After successfully graduating, he started work on 2 May 1976 with Porr, with whom he could gain extensive practical experience for more than 16 years. In this time, he progressed from invoice processing and work preparation to site manager and project manager, later becoming a departmental manager and joint venture director. Some outstanding projects from this time were the Fulpmes power station for Austrian railways ÖBB under Alpine tunnelling conditions, the EG 2 relief channel in Vienna with extensive earthworks, and Vienna underground railway projects with mined tunnelling and complex cut-andcover works in the inner city. In 1990, he was called into the head office to manage the department of earthworks and hydraulic construction and subsequently tunnelling. In this time, he also completed his dissertation and doctorate. He ended his time with Porr on 30 September 1992 with his appointment at the TU to succeed Professor Reismann.

In his 23 years at the TU Vienna from 1992 to 2015, he concentrated on lecturing and science. In countless lectures, Prof. Jodl passed on his rich experience and practical knowledge to the students and taught them commercial thinking.

Numerous publications and scientific works on subjects such as lifecycle costs in bridge building, ecologically efficient decision criteria in civil engineering and cooperative project implementation demonstrate the wide spectrum of his activities, but he also found time for the research area of construction management and construction process technology at the TU Vienna, guest professorship in Sofia and membership of the academic senate of the TU Vienna from 2003 to 2010, In addition, Prof. Jodl was a motivated member of many professional bodies, on the board of the ÖBV, in the ÖIAV, in the Austrian Society for Geomechanics, in the FSV and in the ITA Austria.

After his retirement, Prof. Jodl is remaining active as the managing president of the TU Vienna alumni club, chairman of the Austrian Association for No-dig Construction and member of the supervisory board of the ASFINAG Baumanagement GmbH. I wish to express personal thanks for more than 30 years of consistently good and constructive collaboration and our many interesting discussions.

With best wishes for a busy retirement !

Wolfgang Stipek

Emeritierung Professor Hans Georg Jodl Professor Jodl, Vorstand des Institutes für interdisziplinäres Bauprozessmanagement an der TU Wien, emeritierte am 30. September 2015.

In seiner Abschiedsvorlesung am 27. November 2015 im Kuppelsaal der TU Wien hielt er einen launigen Rückblick auf seinen Werdegang und gab Anregungen für künftige Entwicklungen im Baubetrieb und der Bauverfahrenstechnik. In der anschließenden Emeritierungsfeier wurden seine Leistungen von den Festrednern in sehr persönlich gehaltenen Ansprachen gewürdigt.

Prof. Jodl, geboren am 29. Juni 1947, wuchs in Wien-Mauer auf, besuchte das Bundesrealgymnasium in der Rosasgasse in Wien-Meidling und entschied sich nach der Matura für das Bauingenieurstudium an der TU Wien. Nach erfolgreichem Studienabschluss startete er am 2. Mai 1976 seine Tätigkeit bei Porr, bei der er in etwas mehr als 16 Jahren umfangreiche baupraktische Erfahrungen sammeln konnte. In dieser Zeit entwickelte er sich vom Abrechnungstechniker und Arbeitsvorbereiter zum Bauleiter und Projektleiter und weiter bis zum Abteilungsleiter und Arge-Geschäftsfüh-

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rer. Als besondere Projekte in dieser Zeit sind das KW Fulpmes der ÖBB unter den Bedingungen des alpinen Tunnelbaus, das Entlastungsgerinne EG 2 in Wien mit umfangreichen Erdbaumaßnahmen und die Projekte der Wiener UBahn mit bergmännischem Vortrieb und komplexen Offenen Bauweisen im Innerstädtischen Bereich zu nennen. 1990 erfolgte der Ruf in die Zentrale und die Übernahme der Abteilungsleitung der Erd- und Wasserbau und anschließend der Tunnelbauabteilung. In diese Zeit fielen auch der Abschluss der Dissertation und die Promotion. Mit der Berufung an die TU als Nachfolger von Professor Reismann endete die Zeit bei Porr am 30. September 1992.

In den 23 Jahren an der TU Wien von 1992 bis 2015 waren die Schwerpunkte auf Lehre und Wissenschaft gerichtet. In unzähligen Vorlesungen hat Prof. Jodl seine reiche Erfahrung und sein praxisnahes Wissen den Studenten weitergegeben und ihnen wirtschaftliches Denken vermittelt.

Viele Publikationen und wissenschaftliche Arbeiten, wie Lebenszykluskosten im Brückenbau, Ökoeffiziente

Entscheidungskriterien im Tiefbau und die kooperative Projektabwicklung zeigen das breite Spektrum seiner Aktivitäten. Auch der Forschungsbereich Baubetrieb und Bauverfahrenstechnik an der TU Wien, die Gastprofessur in Sofia und Mitglied im akademischen Senat der TU Wien 2003 bis 2010 waren Schwerpunkte. Darüber hinaus war Prof. Jodl engagiertes Mitglied in vielen Fachorganisationen, im Vorstand des ÖBV, im ÖIAV, in der österreichischen Gesellschaft für Geomechanik, in der FSV und in der ITA-Austria.

Nach seiner Emeritierung ist Prof.

Jodl weiterhin aktiv als Geschäftsführender Präsident TU Wien alumni club, Vorstandsvorsitzender der Österreichischen Vereinigung für grabenloses Bauen und Aufsichtsrat der ASFINAG Baumanagement GmbH. Ich bedanke mich persönlich für die mehr als 30 Jahre dauernde gute und konstruktive Zusammenarbeit und viele interessante Gespräche.

Mit den besten Wünschen für den Unruhestand !

Wolfgang Stipek

Topics Giovanni Barla Andrea Tamburini Sara Del Conte Chiara Giannico

DOI: 10.1002/geot.201500052

InSAR monitoring of tunnel induced ground movements This paper introduces InSAR (Interferometric Synthetic Aperture Radar) as an advanced tool for measuring and monitoring surface ground movements over time, with interest in all phases of a tunnel project, both in urban and non-urban areas. Following a preliminary overview of the technology used to compile radar images of the earth’s surface, the multi-image techniques (Persistent Scatterers Interferometry, PSI) and the InSAR algorithm (SqueeSAR) are briefly outlined. Two examples of InSAR data applied to tunnelling projects are presented. In the first case, the integration of InSAR surface measurements into monitoring by conventional methods is discussed as a tool for providing useful information to study the relationship between tunnelling and surface settlements. In the second case, the temporal evolution of ground displacements provided by SqueeSAR is applied in order to understand the link between tunnel excavation and surface movements, along a slope under passed by two large tunnels.

1 Introduction The Interferometric Synthetic Aperture Radar (InSAR) has become an operational tool for measuring and monitoring ground movements. Compared to traditional surveying techniques, InSAR has the advantage of offering a high density of measurement points over large areas. Advanced InSAR techniques, such as PSInSAR [1] and SqueeSAR [2], developed in the last decade, provide high precision time series of movement that allow to highlight typical displacement patterns, such as changes in ground movement over time as well as seasonal uplift/subsidence cycles.

In recent years, an increase in the use of InSAR for monitoring tunnels in both urban and non-urban areas has taken place. Given the successful worldwide applications in all phases of tunnelling projects (design, excavation/construction, and operation/maintenance), InSAR has been recently included in the “ITAtech Guidelines for Remote Measurements Monitoring Systems” [3]. These guidelines provide recommendations and examples for monitoring projects, which assist tunnel designers, contractors and owners in understanding the benefits and limitations of remote measurement systems.

The unique characteristics of InSAR for addressing these concerns are as follows: – Provide baseline assessment studies prior to construction. By exploiting archived historical satellite imagery, it is possible to identify critical areas where pre-existing

deformation could potentially interfere with tunnel construction/operation.

– Provide a high density of measurement points (thousands per square kilometre) over large areas. The increase of displacement information during excavation supports the characterization of deformation phenomena (i.e. extent, magnitude and behaviour) eventually induced by tunnelling.

– Monitor, identify and characterize any residual deformation after tunnel completion.

In this paper, two examples of InSAR data applied to tunnelling projects are briefly presented. Firstly, the integration of InSAR surface measurements into monitoring by conventional methods provided useful information to study the relationship between tunnelling activities and surface settlements. Secondly, the temporal evolution of ground displacement provided by SqueeSAR was used with the intent to understand the link between tunnel excavation and surface movements.

2 Technology overview InSAR is a remote sensing tool that measures ground displacement [4] [5] [6] [7]. Radar sensors mounted on specific satellites transmit radar signals toward the earth, some of which reflect off objects on the ground, bouncing back to the satellite. These “back scattered” signals are captured by the satellite sensors and are used to compile radar images of the earth’s surface.

The signal phase of a SAR image relates to the distance of the radar from the illuminated targets on the ground. Interferometric Synthetic Aperture Radar (InSAR), also referred to as SAR Interferometry, consists of the phase comparison of SAR images, acquired at different times with slightly different looking angles. The phase difference between two SAR images contains a phase term proportional to the target motion occurring along the sensor-target line-of-sight (LOS) direction during that time interval.

The main limitation of this conventional InSAR approach is the effect of the atmosphere on the propagating signal, resulting in artefacts, which can hamper the precision of the measurements, if not removed. Limitations of the conventional InSAR approach were overcome in the late nineties by the PSInSAR technique [1]. By exploiting

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all the available SAR images gathered during repeated satellite passes over the same area, this technique seeks to identify radar targets exhibiting coherent phase behaviour, namely Permanent Scatterers (PS). It also estimates and removes atmospheric effects via accurate filtering algorithms, in order to measure the displacement affecting each PS. Following this advanced InSAR technique, further multi-image techniques were developed in the last fifteen years, called Persistent Scatterers Interferometry (PSI) techniques. In 2010, a new InSAR algorithm, SqueeSAR, was developed [2]. This second-generation multi-image algorithm enables the identification of higher spatial density of radar targets in non-urban areas and a more effective filtering of atmospheric disturbances affecting InSAR data.

This is achieved by exploiting signal returns from both Permanent Scatterers (PS) and Distributed Scatterers (DS).

PS usually correspond to point-wise scatterers, generally man-made objects, while DS are typically identified from homogeneous ground, scattered outcrops, debris flows, non-cultivated lands and desert areas. This new approach provides additional data in low-reflectivity homogeneous areas. Whatever the type of measurement point (MP) identified by the algorithm (PS or DS), the following information can be retrieved: geographic coordinates of the measurement point (latitude, longitude and elevation), average annual velocity of the measurement point, and time-series of displacement.

MPs can be seen as a “natural” ground network of radar benchmarks, similar to a GPS (Global Positioning System) network. They can be used for monitoring both the displacement of individual structures (a building, for instance), and the evolution of a large displacement field affecting hundreds of square kilometres (due, for example, to subsidence, slope instability, fault creeping, volcanic activity). It should be noted that the MP density is usually much higher than the density of benchmarks used in any conventional geodetic network. MPs can reach very high densities especially in urban areas, where thousands of MP/km2 are usually identified with the new high-resolution satellites. Moreover, MP measurements do not require any installation and fast algorithms allow the update of the information concerning thousands of points quickly and reliably.

A further advantage of SAR interferometry with respect to conventional techniques is the possibility to exploit radar data already acquired, taking advantage of the historical archives of SAR data. The recent introduction of new X-band SAR has further increased the quality of measurements. Higher sensitivity to surface deformation (compared to previous available sensors) and higher spatial resolution (down to 1 m), as well as better temporal frequency of acquisition (down to a few days, rather than a monthly update) have been achieved.

Movement data exhibited by a MP are then relative, not absolute, data. Satellite interferometry provides the deformation rate along the line of sight (LOS), which can be inclined from 18° to 45° with respect to the vertical, depending on satellite and acquisition mode. Satellites are in polar orbits, and therefore pass over the area of interest in two possible directions: ascending, flying from south to north, and descending, from north to south. Results obtained from the processing of an ascending and a descending dataset can be combined to give separate estimates of the vertical and E-W movement.

3 Case study 1 This case study is relevant to a single-track rail tunnel, with a horseshoe shape and 60 m2 cross section, under excavation in an urban area under a depth of cover of 10 to 12 m. Surface settlements were induced along the underground line under construction, where a number of buildings are located. InSAR was used to gain insights into the correlation between the tunnel face advance and the induced surface settlements. This information is of particular interest along a limited length of the same tunnel, where a jet grouting consolidation work from the ground surface was performed, in order to deal with the challenging geologic and hydrologic conditions encountered.

In the area of interest, a highly heterogeneous calcarenite formation, ranging from well cemented to poorly cemented rock, is present from the ground surface down, approximately, to the tunnel crown. Below this elevation, a very fine sandy soil with silt is met up to and below the tunnel invert, where the nearly impervious Numidian Flysch substratum (dark silty claystone with sandstone intercalations) is found. The water table is above the tunnel crown.

Based on the geological and hydrogeological studies performed, in the area a low structural substratum is present, which locally conditions significantly the water flow.

With the jet grouting consolidation work completed, at the beginning of June 2014 tunnel advance started from one side of the area. Just following a 1m excavation length approximately, a face instability phenomenon occurred with a total estimated volume of 300 m3 of water and silty sand entering into the tunnel. Consequently, a subsidence trough was created on the ground surface with significant settlements taking place, which resulted in damages of the surrounding buildings.

As an aid to the displacement-monitored data already available along the tunnel axis with conventional topographic measurements (including a robotic total station), two sets of COSMO-SkyMed data, in both ascending and descending geometries, were acquired, covering a time span of about 5 years before June 2014 (Table 1). To better understand the distribution of induced settlements in the entire tunnelling area, radar data were processed with SqueeSAR and by combining both acquisition geometries,

Table 1. List of processed datasets for Case Study 1 Satellite

Geometry

LOS angle (vs vertical)

Number of images

Period

COSMO-SkyMed

descending

27°

58

June 2009 – June 2014

COSMO-SkyMed

ascending

40°

60

June 2009 – June 2014

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Fig. 1. MPs identified with the combination of ascending and descending data. MPs are colour-coded according to the average vertical displacement rate in the monitored period (June 2009 to June 2014). The displacement time series of a measurement point located along the tunnel (MP1) is shown below

it was possible to separate vertical (Figure 1) from E-W horizontal displacement components.

The vertical displacement time history of a selected measurement point located along the tunnel axis, when the tunnel face was at a distance of 300 m prior to the critical area above, is shown in Figure 1 as an example. It is observed that surface displacements started at the beginning of 2012, followed by a progressive stabilization after the completion of the tunnel. The cumulative vertical displacement in this case was about 65 mm.

A comparison among different displacement time histories taken along the tunnel alignment showed a good correlation between deformation and tunnel face advancement, both in time and extension of the deformed area. Multi-temporal deformation maps obtained by MP interpolation are shown in Figure 2. Each map represents the cumulative vertical displacement measured in six months periods, from January 2012 to June 2014. The greatest displacement deformation rate was measured from January to June 2012. Furthermore, InSAR data pro-

vided a characterization of the entire area before and during tunnel excavation, prior to the significant face instability phenomenon occurred in June 2014.

4 Case study 2 This example relates to two motorway tunnels excavated under a slope, where deep-seated landslides, inventoried as “quiescent landslides” in the landslide database, were reactivated [8]. For a better understanding of the phenomena and identifying any possible correlation between the observed slope displacements and tunnel excavation, InSAR was applied in order to provide both historical displacement data prior to the tunnel excavation and monitoring during and after excavation completion.

Two three-lane tunnels, each with 160 m2 cross section, were excavated full face by conventional methods, under an overburden depth ranging between 50 and 80 m.

Systematic reinforcement measures of the face and of the tunnel surround by means of fibreglass dowels were ap-

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Fig. 2. Multi-temporal deformation maps over a tunnel section; each map represents the cumulative vertical displacements referred to a six-month time interval

plied and the final lining was kept always near to the advancing tunnel face. Tunnelling took place through a flysch rock mass consisting of sandstone-mudstone layers with different thickness, with rock mass quality based on the Geological Strength Index (GSI, see [9]) from fair to poor and, in cases, very poor.

The area above the tunnel was heavily monitored by means of inclinometers and piezometers, including a number of robotic total stations for real time monitoring of the inhabited villages. The two tunnels were excavated with one face preceding the other one of 80 to 100 m, within controlled values of both the convergences of the tunnel perimeter and extrusion deformations ahead of the face.

With evidence of surface and subsurface movements concurrently with tunnel excavation, the decision was taken to acquire InSAR data. The data from both ascending and descending geometries by three different satellites (or satellite constellations) during about a decade (Table 2) were processed with SqueeSAR.

The main results obtained from the analysis let one derive the following observations: – A displacement rate of few mm/year was observed before tunnel excavation, prior to the installation of any other conventional monitoring equipment.

– A sudden acceleration was observed during tunnel excavation, starting from 2011 (displacement rate up to 60 mm/year between 2011 and 2013). In accordance with tunnel excavation and face advance, surface movement developed progressively, with clear evidence of reactivation of the deep-seated landslides.

– After the tunnelling completion (November 2014), a progressive deceleration started to take place, even if at the end of March 2015 a complete stabilization has not yet been reached over the entire area above the tunnels.

– The integration between InSAR and conventional surface displacement measurements (robotic total station and automatic GPS) provided significant help in interpreting the monitoring results within the study area.

Table 2. List of processed datasets for Case Study 2 Satellite

Geometry

LOS angle (vs vertical)

Number of images

Period

RADARSAT 1

descending

34°

119

March 2003 – March 2013

TerraSAR-X

ascending

42°

24

April 2014 – March 2015

TerraSAR-X

descending

35°

28

April 2014 – March 2015

COSMO-SkyMed

descending

31°

16

November 2012 – February 2014

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Fig. 3. Multi-temporal deformation maps over a tunnel section; each map represents the average yearly displacement rate referred to a specific period. On the right, the displacement time series of some MP are reported

Figure 3 shows the evolution of the area in terms of surface displacements from March 2003 to March 2013. Each map represents the average yearly displacement rate referred to a specific period. The first map is relevant to March 2003 – December 2010. No other monitoring network was present on the slope during this time interval.

Given the availability of historical data archives, it is possible to ascertain that the slope was nearly stable before the tunnel reached the study area. The next two maps refer to January 2011 to March 2013 and highlight displacements progressively affecting a wider area of the reactivat-

ed landslide, following tunnel excavation from north to south.

Displacement time history of some MPs is shown in Figures 4 and 5, together with displacement data provided by robotic GPS stations. Data provided by different satellites are separately represented. RADARSAT data (Figure 4) cover the 2003-2013 decade and highlight the initial stage of the reactivation. In order to enable the comparison between the two techniques, it was necessary to project 3D GPS data along the line of sight of the satellite.

Starting from April 2014, dual geometry TerraSAR-X im-

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Fig. 4. InSAR vs GPS displacement time series. InSAR data are obtained by the processing of a descending RADARSAT imagery covering the period March 2003 to March 2013. GPS measurements started in January 2013. The comparison is performed projecting GPS measurements along the satellite line of sight

Fig. 5. GPS vs InSAR displacement time series, vertical (blue) and E-W (red) components. InSAR data are obtained by the combination of ascending and descending TerraSAR-X datasets, covering the period April 2014 to March 2015

ages was processed, enabling the separation between vertical and E-W horizontal components. A good fit between InSAR and GPS east and vertical components are well evidenced in Figure 5.

A good fit along the E component was obtained also for the GPS station represented in Figure 5. For the same point, the vertical component shows a comparable trend, but a seasonal deformation cycle is evident in the GPS data series, not confirmed by the InSAR data. It is noted that in this case, the GPS station was not monumented with a concrete pillar, but the GPS antenna was installed on a

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pre-existing structure that is possibly affected by thermal deformation cycles. Such phenomena are more evident along the vertical component, as often observed in similar conditions. In this case, the MP corresponding to the GPS station does not exactly coincide with the structure itself, even if its location is very close to it.

InSAR data were also used to check the position of some robotic total stations installed along the slope and automatically controlling group of prisms. Thanks to the wide monitored area, InSAR data can be used to calibrate and correct measurements provided by a robotic total sta-

G. Barla/A. Tamburini/S. Del Conte/C. Giannico 路 InSAR monitoring of tunnel induced ground movements

Fig. 6. Example of InSAR displacement time series used to verify and correct the measurements provided by a total station (TS) located inside the landslide area and its reference prisms (RP)

Fig. 7. InSAR data overlapped to the official regional landslide inventory map; MP are colour-coded according to the average displacement rate measured along the satellite line of sight in the period March 2003 to March 2013

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tion in case the station or its reference prisms are located inside an unstable area. This is done in post-processing at every update of SqueeSAR analysis. The bias introduced by the displacement of the robotic total station or one of its reference prisms can be removed using InSAR displacement time series (Figure 6).

Finally, InSAR data were used to verify and update the landslide inventory at regional scale, as they are complementary to more conventional geological and geomorphological analyses. In Figure 7, InSAR data (average displacement rate between March 2003 and March 2013) are represented over the regional landslide inventory map.

Blue and red patterns of the landslide polygons represent “quiescent” and “active” landslides, respectively. A good fit between surface displacement data and the state-of-activity of the mapped landslides can be observed.

[3] ITAtech: Guidelines for Remote Measurements Monitoring Systems. ITAtech Report n.3-V2, 2015.

[4] Hanssen, R. F: Radar Interferometry: Data Interpretation and Error Analysis. Kluwer Academic Publishers, 2001.

[5] Kampes, B. M.: Radar Interferometry: Persistent Scatterer Technique. Springer, 2006.

[6] Ketelaar, V. B. H.: Radar Interferometry: Subsidence Monitoring Techniques. Springer, 2009.

[7] Ferretti, A.: Satellite InSAR Data – Reservoir Monitoring from Space. EAGE Publications, 2014.

[8] Barla, G., Debernardi, D., Perino, A.: Lessons learned from deep-seated landslides activated by tunnel excavation. Geomechanics and Tunnelling 8 (2015), No. 6, pp. 394–401.

[9] Hoek, E., Carter, T. G., Diederichs, M. S.: Quantification of the Geological Strength Index Chart. 47th US Rock Mechanics/Geomechanics Symposium, San Francisco, 2013.

5 Concluding remarks InSAR has been briefly described in conjunction with the most recent advances of the technology, including the multi-image SqueeSAR algorithm. The interest in using this technology for monitoring surface deformation induced by tunnelling in both urban and non-urban areas has been pointed out, with reference to possible applications in all phases of projects, from design to excavation and operation/maintenance.

The first case study is concerned with a single-track rail tunnel excavated in urban area in difficult, geological, hydrogeological and geotechnical conditions. The use of the InSAR for understanding the distribution and assessing the magnitude of surface settlements along the tunnel axis has been illustrated.

The second case study considers the reactivation of deep-seated landslides, during excavation of two highway large tunnels. InSAR data supported the back-analysis, through advanced three-dimensional modelling of the interaction of tunnel excavation and deep-seated landslides, and provided a unique tool to verify and calibrate conventional monitoring data.

Prof. Dr. Eng. Giovanni Barla Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Torino Italy giovanni.barla@polito.it

Geol. Andrea Tamburini, PhD Tele-Rilevamento Europa – TRE Ripa di Porta Ticinese 79 20143 Milano Italy andrea.tamburini@treuropa.com

Geol. Sara Del Conte Tele-Rilevamento Europa – TRE Ripa di Porta Ticinese 79 20143 Milano Italy sara.delconte@treuropa.com

References [1] Ferretti, A., Prati, C., Rocca, F.: Permanent Scatterers in SAR Interferometry. IEEE Trans. Geoscience and Remote Sensing 39 (2001), No. 1, pp. 8–20.

[2] Ferretti, A., Fumagalli, A., Novali, F., Prati, C., Rocca, F., Rucci, A.: A New Algorithm for Processing Interferometric Data-Stacks: SqueeSAR. IEEE Trans. Geoscience and Remote Sensing 49 (2011), No. 9, pp. 3460–3470.

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Eng. Chiara Giannico Tele-Rilevamento Europa – TRE Ripa di Porta Ticinese 79 20143 Milano Italy chiara.giannico@treuropa.com

Topics Klaus Rabensteiner Klaus Chmelina

DOI: 10.1002/geot.201500051

Tunnel monitoring in urban environments Urban tunnel projects such as new metro lines face particular challenges. Shallow overburden, difficult (hydro)geological conditions and sensitive buildings in close proximity are risks that often cannot be avoided, demanding large and complex geotechnical monitoring programmes. This paper considers the current situation of tunnel monitoring in urban environments and describes two specific monitoring solutions, one for shafts and one for structures, and emphasises the importance of efficient data management with the assistance of a tunnel information system.

Finally, the paper gives an overview of recent research activity and emerging sensing technologies.

1 General Tunnelling works are carried out in virtually all large European cities. Numerous new metro lines or extensions, tunnels for inner city railways, roads and sewage lines are under design or construction. The major projects currently prepared or already running are in Copenhagen (Cityringen), London (Crossrail), Stuttgart (Stuttgart 21), Stockholm (Stockholm Bypass), Vienna (Lines U1, U5), Paris (Line 1, CDG Express Airport Line), Thessaloniki (metro) and Sofia (Line 3). Further large projects are underway on all continents.

In all these urban tunnel projects geotechnical monitoring programmes play an important role in mitigating risks associated with the construction works, and are designed to meet the following goals: – Recording the effect of construction works on existing structures, – Providing early warning of critical developments, – Prediction of developments, – Triggering emergency procedures in order to implement mitigation measures, – Optimization of construction methods, – Verifying/confirming design assumptions and design models, – Providing suitable data for the purpose of back-analysis.

Optimally, monitoring already commences three years before the start of civil works (baseline monitoring) to measure movements that are not related to underground excavation, such as natural seasonal variations, creep or other civil works. This baseline data is of great relevance for the correct interpretation of monitoring results obtained during the construction period, which can often last many years. After

completion of civil works, monitoring has to be continued for a period of time (close-out monitoring) until all parameters (e.g. ground settlement) return to their monitored baseline behaviour. In practice, however, this undoubted time requirement is unfortunately often disregarded.

A great variety of state-of-the-art geotechnical monitoring methods and sensors are specified and used in urban tunnel monitoring programmes. Established standards are the precise levelling of pins mounted on buildings and on the ground, optical 3D measurements of prisms on structures using total stations, the use of relative geotechnical sensors such as extensometers, inclinometers, tilt meters, strain gauges, crack meters, load cells, shotcrete strain meters, water levels, piezometers and noise and vibration measurement systems.

However, every urban tunnel project has its own monitoring challenges requiring special solutions. Three such solutions are described below, with the intention of illustrating the potential and complexity of tunnel monitoring in urban environments.

2 Urban tunnel monitoring solutions 2.1 Monitoring of shafts with in-place inclinometers The construction of deep shafts (e.g. for TBM launching chambers or stations) is a highly specialized and risky endeavour, and often affects critical or sensitive structures nearby. Especially in congested areas, diaphragm walling has become the most common method of shaft construction, since such walls can be installed in close proximity to existing structures. To assess the stability of diaphragm walls and safety of works continuously during excavation, a special monitoring solution has been developed for the Cityringen project in Copenhagen.

The solution is based on in-place inclinometers (IPIs) to continuously monitor shaft wall stability (Figure 1) during excavation. Eight special inclinometer casings were installed in each shaft on the project, installed directly into the diaphragm wall by a special technique. The casings extend from the top (crown) of the wall down to about 10 m below the bottom of the shaft at a depth that is assumed to be stable. In a first phase (before the start of shaft excavation), daily measurements were carried out with a manual inclinometer probe. Later, when shaft excavation commences, the probe is replaced by in-place inclinometers (IPIs) to provide deformation curves automati-

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K. Rabensteiner/K. Chmelina · Tunnel monitoring in urban environments

Fig. 1. Shaft instrumented with eight in-place inclinometers in the diaphragm wall and further sensors

Fig. 2. In-place inclinometer sensor in casing

cally every few hours. These transfer their data online to a central tunnel information system.

An IPI consists of a series of two-axis inclinometer sensors (Figure 2), each based on a high accuracy MEMS accelerometer, connected to each other as a chain. Each sensor provides the tilt with respect to gravity with an accuracy of ± 0.05 mm/m. The complete sensor chain is po-

sitioned inside the inclinometer casing. The individual sensors are fixed by a spring-loaded pivoted wheel set and connected to each other by ball joints. The measured tilts are multiplied by the associated sensor length of 3 m to obtain horizontal displacements, which are then accumulated to derive the desired deformation curve.

Figure 3 shows some examples of deformation curves obtained during the eight-month excavation phase. The displacements are recorded in two directions, one perpendicular (Deviation A) and one parallel (Deviation B) to the diaphragm wall. The left diagram indicates significant horizontal displacements due to excavation activities of up to 23 mm towards the shaft centre at a depth of 16 m.

In addition, the shaft has five levels of preloaded struts. The development of strut loads during excavation was monitored by six to eight strain gauges per strut and load cells. Furthermore, levelling pins were installed in the ground around the shaft and on all surrounding structures (buildings) and monitored daily by precise levelling. 3D prisms were also installed on selected structures and measured from three robotic total stations every 30 min. Finally, several monitoring wells are provided, equipped with automatic water level sensors.

The solution is seen as a good example of how to combine different absolute geodetic and relative geotechnical monitoring sensors and methods in a suitable manner to obtain all relevant monitoring information needed for interpretation. It also presents an economically acceptable solution, since the number of monitoring sensors and measurements taken is reduced to those really needed.

Nevertheless, as the monitoring system is operated fully automatically it provides monitoring results at high frequencies 24/7.

2.2 Monitoring of structures by use of robotic total stations In the Cityringen project special attention has been paid to 3D displacement monitoring of existing structures, both above and below ground. Therefore, metro stations under

Fig. 3. Deformation curves for a diaphragm wall measured by an in-place inclinometer (IPI)

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Fig. 5. Monitored building with robotic total station and 3D prisms on the façade (left) and total station on pillar (right)

construction, shafts, sensitive buildings, roads and existing tunnels located in the influence zone were all equipped with 3D prisms that are surveyed by automated high-precision total stations. The instruments either measure independently or are interconnected, setting up monitoring networks in order to cover larger deformation areas (Figure 4). All total stations are centrally controlled and monitored by a PC over WLAN.

At a minimum, every sensitive building within the monitoring zone is equipped with six 3D prisms (Figure 5) every three floors, giving a total of 4,500 prisms in the project. Both the front and rear faces of each building are monitored with a standard measurement interval of two hours. In special situations, the measuring frequency is reduced to one hour or 30 minutes depending on the particular number of points to be measured. In critical cases, e.g.

Foto: shutterstock

Fig. 4. 3D displacement monitoring of a church and further buildings in the zone of influence involving seven interconnected robotic total stations

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K. Rabensteiner/K. Chmelina · Tunnel monitoring in urban environments

Fig. 6. Examples of underground installations of robotic total station systems for 3D displacement monitoring (left: Crossrail project London, right: Tyne tunnel project, UK)

when a TBM crosses existing tunnel tubes, the measurement interval is even reduced to 90 seconds in order to be able to give constant feedback of the 3D displacements during the crossing.

More than 100 robotic total stations are operating in parallel in the project and had provided more than 60 million measurements by October 2015. Their robustness, long-term stability, ease of maintenance and installation, almost noiseless operation, high degree of automation and especially the high quality of the results have significantly contributed to the success of the project and give the technology a major role in the overall geotechnical monitoring programme.

The stated advantages not only make total stations valuable instruments above ground but numerous underground installations have also been used successfully on the project. Installation examples can also be given from many other projects (Figure 6).

In recent years, the use of the reflectorless distance measurement option of these instruments has enabled completely new applications, and made total stations even more flexible. Using appropriate software algorithms, even reflectorless monitoring of road surfaces (Figures 7 and 8) and building facades can be performed successfully.

Automatic 3D displacement monitoring with robotic total stations is a success story of a highly specialized geodetic sensing technique. Total stations are now playing a decisive role in geotechnical monitoring. The current integration of additional sensing techniques such as 3D laser scanning and video imaging into these instruments will allow new applications and make them even more relevant in future.

2.3 Monitoring data management with a tunnel information system Large-scale monitoring programmes are now being designed and implemented in urban tunnelling, comprising surface and in-ground monitoring measurements taken with growing numbers of different kinds of latest-generation monitoring systems and sensors. Up to 20,000 or more monitoring points and sensors can be found in modern urban tunnel projects. While both manual and automatic measurements are still carried out, most data is al-

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Geomechanics and Tunnelling 9 (2016), No. 1

Fig. 7. Reflectorless monitoring of a road surface by use of two interconnected robotic total stations installed on high pillars at each side of a highway (Huntington Beach, USA)

Fig. 8. Visualization of settlements monitored reflectorless by two interconnected robotic total stations

ready produced by automatic sensors and a clear further trend towards real-time monitoring is visible.

The consequence is a rapid increase of monitoring data volumes and a growing challenge to handle the seamless input/import of data stemming from numerous types

K. Rabensteiner/K. Chmelina · Tunnel monitoring in urban environments

Fig. 9. User interface of the tunnel information system KRONOS of Geodata showing total project map and a particular monitoring area of the Cityringen project in Copenhagen (as shown in Fig. 4)

of manual and automatic measurement systems and sensors spread all over a city. These produce data records independently from each other, at different times, at different and changing measuring frequencies and in heterogeneous formats. All the data records have to be acquired,

queued and checked in a fast, systematic and intelligent way prior to further processing, analysis and decision making.

To cope with this problem, tunnel information systems have been developed (Figure 9) and have become in-

Rock Mechanics Based on an Anisotropic Jointed Rock Model (AJRM)

Walter Wittke Rock Mechanics Based on an Anisotropic Jointed Rock Model (AJRM) 2014. 876 pages. € 149,–* ISBN 978-3-433-03079-0 Also available as

This book focuses on the fundamentals of rock mechanics as a basis for the safe and economical design and construction of tunnels, dam foundations and slopes in jointed and anisotropic rock. It is divided into four main parts: – – – –

Fundamentals and models Analysis and design methods Exploration, testing and monitoring Applications and case histories.

The rock mechanical models presented account for the influence of discontinuities on the stressstrain behavior and the permeability of jointed rock masses.

Order online: www.ernst-und-sohn.de

Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG

Customer Service: Wiley-VCH Tel. +49 (0)6201 606-400 Fax +49 (0)6201 606-184 Boschstraße 12 service@wiley-vch.de D-69469 Weinheim

* € Prices are valid in Germany, exclusively, and subject to alterations. Prices incl. VAT. excl. shipping. 1050106_dp

K. Rabensteiner/K. Chmelina · Tunnel monitoring in urban environments

dispensable. They provide interfaces to all involved users, be it data providers (e.g. monitoring teams and systems) or recipients (e.g. geotechnical experts) and manage all data in one central database or several distributed databases.

Their particular advantage is that not only monitoring data can be managed efficiently but also all further data that is relevant for interpretation such as: – TBM data (e.g. operating parameters such as thrust, penetration, actual machine status), – Construction progress data (e.g. the current station of TBMs and tunnel faces, the current excavation depth of shafts, currently installed piles), – Building survey data (e.g. the location, type, condition and risk category of existing buildings and foundations), – Geotechnical/(hydro)geological data (e.g. logs of boreholes, in-situ and laboratory tests, data from groundwater monitoring) – Environmental data (e.g. meteorological data, noise and vibration) – Ground treatment data (e.g. drilling parameters, advance rates, grouting data) – Design data (e.g. drawings, threshold values for monitored parameters) A great benefit offered by these systems is automatic services such as reporting, alarming and monitoring control.

Monitoring reports no longer have to be produced manually but are created and distributed automatically at specified time intervals. Complex alarm plans can be defined and executed comprising alarm levels, rules, recipients and actions making sure that critical developments, missing or erroneous monitoring data and non-functioning monitoring systems are recognized immediately. Automatic control functions ensure that data is collected, checked and transferred as planned, monitoring systems are reconfigured (e.g. apply higher measuring frequencies when a TBM approaches) and new monitoring systems are detected, localized and registered automatically (plug and play).

3 Conclusion and outlook Tunnel monitoring in urban environments requires particular solutions to integrate and combine modern sensors with IT components for data acquisition, transfer and management. An optimal design of a monitoring programme focuses on the objects to be measured and the objectives to be achieved. Under- and overdimensioning of monitoring should be avoided, which means selecting suitable types, numbers and locations for sensors and devices, and specifying sensing frequencies with regard to the expected and occurring deformation rates. Flexibility is a further key to success, meaning that the dynamics of a project have to be taken into account and monitoring pro-

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Geomechanics and Tunnelling 9 (2016), No. 1

grammes have to be rapidly adaptable to new situations.

Sudden changes of sensor locations, frequent installation and de-installation of new sensors etc. have to be managed smoothly without causing problems such as downtimes and longer interruptions. As an example, sensors must be recognized by and register themselves automatically to the central tunnel information system.

Currently, sensors are becoming more and more miniaturized (MEMS) and smart communication of monitoring data is increasingly based on wireless technologies such as WLAN, ZigBee, Bluetooth, GSM/LTE and LowPan to replace cables wherever possible. Tunnel information systems transfer enormous data amounts through the Internet, and preferably are themselves located in the cloud to avoid local software installation. Many web-services have been developed for data analysis and simulation.

This intensive Internet use has recently led to new issues such as security concerns (cyber attacks), data traffic problems (bandwidth limitations) and also energy consumption. Current research activities (e.g. the Eureka project ASUA, http://asua.netcad.com) are therefore concentrating on wireless sensor networks (WSN) to ensure optimal (energy-efficient) routing of monitoring data, embedded systems for intelligent local data processing (e.g. model-based data reduction before transmission) and energy harvesting (solar, wind). The issues can be seen as classical smart city problems that are slowly also entering the tunnelling domain.

New sensing technologies are emerging, for example radar interferometry (INSAR) for ground settlement monitoring and fibre optics for structural monitoring (e.g. for the monitoring of strain in precast tunnel segments). They will soon be regarded as standard methods and extend the great arsenal of tunnel monitoring techniques.

Dipl.-Ing. Klaus Rabensteiner Geodata Group Hans-Kudlich-Straße 28 A-8700 Leoben Austria klaus.rabensteiner@geodata.at

Dr.-Ing. Klaus Chmelina Geodata Group Hütteldorferstraße 85 A-1150 Vienna Austria klaus.chmelina@geodata.at

Topics Giovanni Barla Francesco Antolini Giovanni Gigli

DOI: 10.1002/geot.201500050

3D Laser scanner and thermography for tunnel discontinuity mapping Discontinuity mapping of tunnels during excavation is a key component of the interactive observational design approach. One requirement is to verify the geological and geomechanical predictions made at the design stage. In recent years, fully automated, remote-based techniques such as Terrestrial Laser Scanning (TLS) and Infrared Thermography (IRT) have become available, and their applications have increased, reducing the time needed to obtain complete geomechanical mapping of the rock mass.

The effective use of these techniques is of great interest in tunnelling where the need arises for the operators to work close to the tunnel face. This paper presents a discussion of the main technical features of TLS and IRT, as well as data processing methods, followed by a case study of a tunnel excavated in the NW Italian Alps.

1 Introduction Due to the difficult conditions at the tunnel face during excavation, the adoption of methods to make it possible to obtain the data needed for rock mass characterization remotely is highly desirable. Terrestrial Laser Scanning (TLS) and Infrared Thermography (IRT) have experienced significant development in surface applications (rock slopes, quarries, surface mines). They have reached high levels of accuracy and resolution and become suitable for quantitative discontinuity mapping of the rock mass [1] [2]. In particular, considering the reduced acquisition and processing time, these techniques can be adopted underground in order to reduce the presence of people at the face and thus increase safety.

In this paper, these techniques are described with reference to a case study (the Ceppo Morelli Tunnel along the SR 549 “di Macugnaga”, in Italy). It shows the advantages of obtaining the data for rock mass chararacterization and assessing the stability of the tunnel face efficiently and in safe conditions. As is well-known, efficient and accurate collection of discontinuity data is an essential component of the observational design approach used in tunnel engineering, with the need to compare the conditions anticipated at the design stage with those actually encountered during excavation.

2 Technology overview Terrestrial Laser Scanning (TLS) provides high-resolution 3D models of the surveyed rock mass surfaces. New TLS

devices, with their growing range and resolution, are becoming remarkable tools for rock mass characterization. Time-of-flight laser scanners enable measurements of scanner-object distances by calculating the round-trip time a laser pulse (near-infrared wavelength) takes to reach the object surface from the point of emission and return.

The entire field of view is scanned by changing the view directions of the laser rangefinder through a system of rotating mirrors, and the related horizontal and vertical angles are measured with a very high data acquisition rate (up to many thousands points per second). The Cartesian coordinates of each point on the scanned object surface are calculated given the measured distance and scan angles, enabling the acquisition of very dense point clouds for the creation of 3D models. These products are usually textured in true colours, thanks to the calibrated high-resolution digital camera associated with the scanner. Given the high accuracy (some mm) and resolution (up to many thousands of points per square metre) of the point clouds, even the smallest features of the rock mass can be detected and investigated.

Infrared Thermography (IRT), called also thermal imaging, is a remote sensing technique capable of mapping the evolution of the surface temperature pattern, leading to the detection of thermal anomalies within the investigated object. In recent years, IRT has undergone a significant widening of its scope of application with the technological development of portable and cost-effective thermal imaging cameras as well as the fast measurement and processing times of thermographic data. Nevertheless, apart from a few interesting experimental studies in slope analysis [3] [4] [5], IRT has still not yet been applied in tunnelling.

The product of a thermographic survey is a thermal image (or thermogram). This, after correction of the sensitive parameters (object emissivity, path length, air temperature, and humidity), constitutes a surface temperature map of the investigated scenario. The rate of heat transfer through a solid body regulates the amount of energy radiated by its surface [6]. If an inhomogeneity exists within the material, the local radiant temperature will differ from that of surrounding areas. Therefore, mapping the radiant temperature can lead to the detection of irregular thermal patterns (thermal anomalies) within the investigated object.

© 2016 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin · Geomechanics and Tunnelling 9 (2016), No. 1

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G. Barla/F. Antolini/G. Gigli · 3D Laser scanner and thermography for tunnel discontinuity mapping

In the analysis of a rock mass, thermal anomalies can reveal the presence of potentially critical conditions. This is the case with: – Structural discontinuities (due to the cooling/heating effect of air circulating within open fractures, different thermal transfer capacity of the infill material compared to the exposed sound rock), – Moisture or seepage zones (due to the surface cooling caused by water evaporation).

It is clear that the 3D geometry of a rock face obtained with TLS can be textured by means of IRT thermal images, opening up the opportunity of exploiting the advantages of both techniques.

Traditional discontinuity mapping is performed in situ, either in one dimension (scanline method) or two dimensions (window method), and requires direct access to the rock face for the collection of the parameters of interest. For practical and safety reasons, traditional geomechanical surveys are often carried out on limited sectors of the rock face, and do not usually provide data for spatially complete geometrical discontinuity mapping. This lack of spatial representativity of geomechanical data is even more important in tunnel applications.

With the aim of overcoming this limitation, semi-automatic geomechanical analyses of data remotely acquired by TLS and IRT techniques can be performed. The parameters extracted, integrated with the high-resolution 3D model, can be useful for the interpretation and analysis of rock instability affecting the investigated rock face.

This can be undertaken by means of probabilistic (i.e kinematic) and deterministic (i.e. stability) analyses (Figure 1).

According to ISRM [7], a set of parameters characterizing the discontinuities is needed for the quantitative description of a rock mass, i.e. orientation, spacing, persistence, roughness, wall strength, aperture, filling, seepage, number of joint sets, and block size. In order to obtain these parameters, a remote sensing approach exploiting the already mentioned capabilities of both the TLS and IRT can therefore be adopted. This requires the extraction

Fig. 1. Flow chart of the proposed integration between TLS and IRT

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Geomechanics and Tunnelling 9 (2016), No. 1

of clusters of points belonging to the same discontinuity plane from the point cloud with the final aim of finding individual discontinuity sets. The approach used in this paper is described in detail in [8] and is based on the definition of least squares fitting planes on clusters of points extracted by moving a sampling cube on the point cloud.

If the associated standard deviation is below a threshold value, the cluster is considered valid. By applying geometric criteria, it is possible to join all the clusters lying on the same surface and isolate discontinuity planes as shown in the example in Figure 2. Once the individual discontinuities have been extracted, their orientation, size and location are known, so the main joint sets can be defined, based for example on contour plots (e.g. equal area or Lambert-Schmidt net, Figure 2c) or other statistical methods, and their geometrical properties (persistence and spacing) calculated. Block sizes (Vb) are then evaluated by using the correlation procedure proposed by Palmstrom [9]: Vb = β × Jv3 where Jv is the Volumetric Joint Count and β is the block shape factor, which can be estimated by the following empirical relation: β = 20 + 7a3/a1 where a1 and a3 are the shortest and longest dimensions of the rock block.

One of the most important parameters of a rock discontinuity is the roughness. It is well known that the roughness of a discontinuity influences its shear strength.

The most practical method for estimating the roughness of a discontinuity surface is to compare the sampled roughness profiles with the standard profiles given by Barton and Choubey [10]. It is observed that the discontinuity roughness is characterized by a marked scale effect [11] and ISRM [7] suggested sampling the local surface orientation with a compass and disc clinometers with different diameters.

A similar approach can be performed virtually on the high resolution TLS point cloud by moving a searching cube with different dimensions (0.1 m, 0.2 m, 0.4 m, 1 m, 2 m and maximum surface persistence) along the selected discontinuity. The best fitting plane dip and dip direction are then obtained, and by plotting them on a stereogram, the discontinuity roughness angles at various scales can be measured. Finally, discontinuity seepage can be qualitatively evaluated by observing the high-resolution point cloud coloured by reflectance or with IRT images as illustrated in Figure 3.

For the definition of the main instability mechanisms affecting the investigated rock face, a spatial kinematic analysis can be performed by using the discontinuity orientation data extracted from the point cloud. This enables definition of where a particular instability mechanism is kinematically feasible, given the geometry of the face and the orientation of discontinuities [12] [13].

The main instability mechanisms investigated with this approach can be plane failure, wedge failure, and block and flexural toppling. A kinematic hazard index for

G. Barla/F. Antolini/G. Gigli ¡ 3D Laser scanner and thermography for tunnel discontinuity mapping

Fig. 2. Example of rock mass discontinuity extraction from high resolution point cloud: a) point cloud coloured based on planarity; b) polygons delimiting the extracted discontinuities coloured based on the different joint sets attribution; c) stereoplot of the extracted discontinuities

Fig. 3. Example of discontinuity seepage evaluation from a) thermal images and b) reflectance coloured point cloud

each instability mechanism is then defined [14]. Finally, a true 3D kinematic analysis is performed on each portion of the high resolution 3D model by applying the method proposed in [15], which extends the validity of kinematic analysis concepts applied to overhanging slopes [16] [17].

3 Case study The Ceppo Morelli Tunnel on the route of the SR 549 “di Macugnaga� is located in the NW Italian Alps (close to the Italian-Swiss border and the Mount Rosa Massif). It was

Geomechanics and Tunnelling 9 (2016), No. 1

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G. Barla/F. Antolini/G. Gigli 路 3D Laser scanner and thermography for tunnel discontinuity mapping

excavated to bypass a landslide on the left side of the Anzasca river, which damaged the road stretch between the villages of Campioli to the West and Prequartera to the East during the October 2000 Northern Piedmont flooding in Italy (Figure 4).

The landslide is a reactivation of a deep-seated gravitational slope deformation (DSGSD), covering most of the left side of the Anzasca valley, near the village of Ceppo Morelli [18] [19]. The October 2000 reactivation of the DSGSD involved an area of 160,000 m2, causing the collapse, through multiple failures, of an estimated rock volume of 4 to 6 m. m3. Some rock blocks with volumes even greater than 300 m3 reached the valley floor, damaging the road and endangering the villages of Campioli and Prequartera (see Figure 4).

Polymetamorphic mica schists and orthogneisses, belonging to the Penninic nappe of Monte Rosa, crop out along the upper Anzasca valley sector. Glacial till and fluvio-glacial deposits (gravel, pebbles and blocks in a sandy silty matrix) lie unconformably over the bedrock, while talus/scree deposits, mainly consisting of coarse material locally in sandy-loam matrix, are very common at the base of the main cliffs. The structural setting of the Monte Rosa

nappe is characterized by the presence of regional schistosity, dipping towards the SW with medium-angle inclination (<50掳), and is associated with the development of isoclinal folds with axes generally also dipping towards the SW. The groundwater flow is directly influenced by the permeability of soil and rock in the area. In particular, fluvio-glacial and glacial till deposits are characterized by medium to high permeability and generally host aquifers with hydraulic connection to the surface drainage network. Colluvial deposits and slope debris generally host perched water tables directly recharged by rainfalls. Inside the bedrock, which is characterized by a negligible primary permeability, water circulation is instead concentrated along joints and faults. Brittle fault zones generally host the main acquifers which can be both unconfined and confined.

The geological profile along the tunnel axis, based on the geological-geomechanical mapping during excavation of a pilot tunnel, is shown in Figure 5 [19]. At the tunnel portals (Prequartera on the east side and Campioli on the west side), excavation took place through debris and landslide deposits. Inside the rock mass of the Monte Rosa

Fig. 4. Location of the Ceppo Morelli Tunnel (source of the orthophoto: Google maps)

Fig. 5. Geological profile of the Ceppo Morelli Tunnel

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Geomechanics and Tunnelling 9 (2016), No. 1

G. Barla/F. Antolini/G. Gigli · 3D Laser scanner and thermography for tunnel discontinuity mapping

Fig. 6. a) Location of the scans and tunnel face point cloud; b) point cloud coloured based on optical camera images; c) point cloud coloured based on the false-color infrared thermal map

nappe, high-angle brittle tectonic fault zones, characterized respectively by NW-SE and SW-NE trends, were recognised. These zones needed to be crossed by the tunnel.

During excavation from the West portal (Campioli), both TLS and IRT techniques were applied to the tunnel face at chainage 235.5 m. The main objective was to create a 3D geomechanical model of the rock mass and to identify instabilities forming at the tunnel face and along the tunnel perimeter. TLS scanning was undertaken from two different points, referred to as “Center” and “Sidewall”, located at a distance of 14 m and 6 m from the face, thus allowing the acquisition of a 22 · 106 point cloud, as shown in Figure 6.

Prior to scanning, cylindrical reflective targets were installed on the monitored scenario. These target points, due to their brightness, can be easily recognized in the point cloud, thus allowing easy combination of the different views and appropriate georeferencing operations.

The 3D point cloud shown in Figure 6a clearly highlights the surface of the rock mass at the tunnel face and on the side walls, with steel ribs installed during face advance being visible. Figure 6b depicts the same point cloud superimposed on the optical images taken by a high resolution camera coupled with the laser scanner instrument. The same point cloud with the false colour thermal view superposed is illustrated in Figure 6c. The analysis of the thermal map shows a main sector with a lower surface temperature on the right side of the tunnel face. This anomaly is related to the presence of water. No further thermal anomalies are visible on the same tunnel face.

With the intention of defining the excavation profile and to highlight the presence of overbreaks, the laser scanner point cloud could then be used to determine the distance between the extrados of the steel ribs and the exca-

vation contour as shown in Figure 7. The presence of a typical sector where the distance of the tunnel profile from the steel ribs reaches 1.4 m is easily identified, thus pointing out an important geometric anomaly along the tunnel contour with evidence of rock block detachment and overbreak.

From the point cloud, the digital surface model (DSM) of the rock mass was formed by means of 590,000 triangular polygons. The analysis allowed the indentification and extraction of 869 planar features, corresponding to all the discontinuities in the rock mass, as illustrated in Figure 8.

It should be noted that due to the very high spatial resolution of the TLS, a single highly persistent discontinuity surface, which is not perfectly planar, may be fragmented by the identification algorithm into a number of artificial “sub-surfaces”. Therefore, in this case the number of discontinuities extracted through the TLS may have been slightly overestimated.

With the aim of better discriminating the main discontinuity sets with traditional contouring methods, an inverse form of the Terzaghi correction (ω) can be applied to compensate the bias introduced in favour of the planes, which are perpendicular to the line of sight of the laser scanner: ω = 1/|cosΘ| where Θ is the angle between the scan direction and the normal to the rock face.

The analysis of the weighted distribution of the discontinuity poles detected by TLS has highlighted the presence of at least seven different discontinuity sets shown in Figure 8a with orientations being indicated in Table 1.

Geomechanics and Tunnelling 9 (2016), No. 1

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G. Barla/F. Antolini/G. Gigli 路 3D Laser scanner and thermography for tunnel discontinuity mapping

Fig. 7. Calculated distance between the extrados of the steel ribs and the excavation perimeter; the red circle highlights a geometric anomaly along the profile

Fig. 8. Results of the TLS geomechanical survey: a) weighted poles stereoplot showing the discontinuity sets; b) stereoplot of the mean planes of the discontinuity sets; the black circles indicate the tunnel direction; c) segmentation of TLS point cloud showing the discontinuity sets identified

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Geomechanics and Tunnelling 9 (2016), No. 1

G. Barla/F. Antolini/G. Gigli ¡ 3D Laser scanner and thermography for tunnel discontinuity mapping

Table 1. Orientation of the discontinuity sets identified by TLS mapping (see Fig. 8a) Discontinuity set

Dip direction [°]

Dip [°]

KA

224

54

KB

325

89

KC

067

62

KD

291

82

KE

171

57

KF

105

25

KG

060

89

As expected, the TLS mapping identifies a larger number of discontinuity sets while confirming, with slight variations, the orientation of the three joint sets (S1, S2 and S4 shown as triangular marks in Figure 8a) identified with a conventional geologic mapping of the tunnel face.

In particular, these three sets correspond to the schistosity planes (S1-KA), to sub-vertical discontinuities which cross the tunnel face (S2-KB and KD) and to discontinuities dipping toward the tunnel face (S4-KC).

The TLS data are further compared, a posteriori, with the results of conventional geomechanical mappings carried out during tunnel excavation as illustrated in Figure 9. The comparison highlights that, similar to the TLS results, seven main discontinuity sets are present. It should be noted, however, that the conventional mapping does not indentify all the discontinuity sets in a single tunnel section. The presence of the schistosity planes (S1-KA) and of the (S4-KC) sets is well identified in both cases. A greater variability is visible in the schistosity orientation.

Fig. 9. Pole plot of the discontinuities from chainage 87.0 to chainage 229.5 through conventional geological mapping of the tunnel faces; the black circles indicate the tunnel direction

As expected, the TLS mapping highlights a more complex rock mass structure when compared with the results of conventional mapping of the tunnel face during excavation. The structural complexity, which is identified, obviously affects the kinematic and stability analysis at the roof, on the sidewalls and on the tunnel face. As an example, Figure 10 illustrates rock blocks forming on a selected portion of the tunnel face, together with the onset of the instability modes which can be identified.

Fig. 10. Detail of the upper left portion of the tunnel face: box a) rock wedge generated by the intersection of S1-KA and S4-KC sets; box b) detachment niche generated by the intersection of S1-KA, S2-KB and S4-KC sets; box c) detachment niche generated by three mutual orthogonal sets (S3-KD, S7-KG and KF)

Geomechanics and Tunnelling 9 (2016), No. 1

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G. Barla/F. Antolini/G. Gigli · 3D Laser scanner and thermography for tunnel discontinuity mapping

4 Concluding remarks Terrestrial Laser Scanning (TLS) and Infrared Thermography (IRT) have been described with emphasis on their application to tunnelling in order to perform quantitative discontinuity mapping of the rock mass at the face during excavation. The reduced acquisition and processing time, which can now be achieved, have been pointed out together with the increased safety conditions for the operators. A case study has been illustrated in order to show a typical application of the two methods for discontinuity mapping at the tunnel face.

It has been shown that a three-dimensional geomechanical model of the rock mass can be created as the result of TLS scanning in order to identify rock instabilities forming at the tunnel face and along the tunnel perimeter.

The TLS data have been compared with the results of conventional geomechanical mapping carried out during tunnel excavation. TLS mapping is shown to highlight a more complex rock mass structure when compared with the results of conventional mapping of the tunnel face. The structural complexity that is identified obviously affects the kinematic and stability analysis at the roof, on the sidewalls and on the tunnel face.

References [1] Abellán, A., Jaboyedoff, M., Oppikofer, T., Vilaplana, J. M.: Detection of millimetric deformation using a terrestrial laser scanner: experiment and application to a rockfall event. Nat. Hazards Earth Syst. Sci. 9 (2009), pp. 365–372.

[2] Monserrat, O., Crosetto, M.: Deformation measurement using terrestrial laser scanning data and least squares 3D surface matching. ISPRS Journ,al of Photogrammetry & Remote Sensing 63 (2008), pp. 142–154.

[3] Wu, J., Lin, H., Lee, D., Fang, S.: Integrity assessment of rock mass behind the shotcreted slope using thermography.

Engineering Geology 80, 1–2, (2005), pp. 164–173.

[4] Baron, I., Beckovský, D., Míca, L.: Application of infrared thermography for mapping open fractures in deep-seated rockslides and unstable cliffs. Landslides 11 (2014), 1, pp.

15–27.

[5] Gigli, G., Frodella, W., Garfagnoli, F., Morelli, S., Mugnai, F., Menna, F., Casagli, N.: 3-D geomechanical rock mass characterization for the evaluation of rockslide susceptibility scenarios. Landslides 11 (2014), 1, pp. 131–140.

[6] Teza, G., Marcato, G., Castelli, E., Galgaro, A.: IRTROCK: a matlab toolbox for contactless recognition of surface and shallow weakness traces of a rock mass by infrared thermography. Computers & Geosciences 45 (2012), pp. 109–118.

[7] International Society of Rock Mechanics – ISRM: Suggested methods for the quantitative description of discontinuities in rock masses. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 15 (1978), pp.

319–368.

[8] Gigli, G., Casagli, N.: Semi-automatic extraction of rock mass structural data from high-resolution LIDAR point clouds. International Journal of Rock Mechanics and Mining Sciences 48 (2011), 2, pp. 187–198.

[9] Palmström, A.: Measurement and characterization of rock mass jointing. In Sharma, Saxena (eds.): In-situ characterization of rocks. pp. 49-97. Rotterdam: Balkema publishers, 2001.

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[10] Barton, N. R., Choubey, V.: The shear strength of rock joints in theory and practice. Rock Mechanics 10 (1977), pp. 1–54.

[11] Barton, N. R., Bandis, S.: Effects of block size on the shear behavior of jointed rock. Proceedings of the 23rd U.S. Symposium on Rock Mechanics. Keynote Lecture, pp. 739–760, 1982.

[12] Goodman, R. E., Bray, J. W.: Toppling of rock slopes.

ASCE Specialty Conference on Rock Engineering for Foundations and Slopes, Boulder Colorado, pp. 201–234, 1976.

[13] Hoek, E., Bray, J. W.: Rock slope engineering. Revised third edition. Institute of Mining and Metallurgy, London, 1981.

[14] Casagli, N., Pini, G.: Analisi cinematica della stabilità di versanti naturali e fronti di scavo in roccia. Geologia Applicata e Idrogeologia 28 (1993), pp. 223–232.

[15] Lombardi, L.: Nuove tecnologie di rilevamento e di analisi di dati goemeccanici per la valutazione della sicurezza. Ph.D. Thesis, Università degli studi di Firenze, 2007 (in Italian).

[16] Gigli, G., Frodella, W., Mugnai, F., Tapete, D., Cigna, F., Fanti, R., Intrieri, E., Lombardi, L.: Instability mechanisms affecting cultural heritage sites in the Maltese Archipelago. Nat. Hazards Earth Syst. Sci. 12 (2012), pp. 1–21.

[17] Gigli, G., Frodella, W., Garfagnoli, F., Morelli, S., Mugnai, F., Menna, F., Casagli, N.: 3-D geomechanical rock mass characterization for the evaluation of rockslide susceptibility scenarios. Landslides (2013), 1–10.

[18] Amatruda, G., Castelli, M., Forlati, F., Hurlimann, M., Ledesma, A., Morelli, M., Paro, L., Piana, F., Pirulli, M., Polino, R., Prat, P., Ramasco, M., Scavia, C., Troisi, C.: The Ceppo Morelli rockslide. Identification and mitigation of large landslides in Europe: advances in risk assessment, pp.

181–226. London: Taylor & Francis, 2004.

[19] Longo, S., Oreste, P.: Ceppo Morelli Block-Falls Probability Study to Support the Decision of Excavating a by-Pass Tunnel. Am. J. Eng. Applied Sci. 3 (2010), pp. 723–727.

Prof. Dr. Eng. Giovanni Barla Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Torino, Italy giovanni.barla@polito.it

Dr. Francesco Antolini Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Torino, Italy francesco.antolini@polito.it

Dr. Giovanni Gigli Università degli Studi di Firenze Via Giorgio la Pira 4 50121 Firenze, Italy giovanni.gigli@unifi.it

Topics D. Scott Kieffer Gerald Valentin Klaus Unterberger

DOI: 10.1002/geot.201500047

Continuous real-time slope monitoring of the Ingelsberg in Bad Hofgastein, Austria The Ingelsberg in Bad Hofgastein, Austria, is a highly hazardous mountain slope in the State of Salzburg. The Ingelsberg exhibits periodic episodes of instability, prompting major efforts to construct rock fall retention basins and safety nets to mitigate risks associated with future slope failures. As the results of traditional slope monitoring have proved rather ambiguous, continuous realtime monitoring of the Ingelsberg was performed from March 2013 through July 2014. The monitoring was undertaken with a Ground Based Interferometric Synthetic Aperture Radar (GBInSAR). The data set of approximately 130,000 radar scans represent the first long-term GB-InSAR measurements made in Austria, and indicate an episodic pseudo-sheeting failure process, somewhat analogous to the calving of a glacier front. Furthermore, reasonable time of failure predictions for rock fall events having volumes of only several tens of cubic meters could be made from the data set. The GB-InSAR monitoring provides significant insight regarding the overall slope behavior, failure tendencies, and associated geotechnical hazards of the Ingelsberg.

1 Introduction The Ingelsberg in Bad Hofgastein, Austria, is presently one of the most hazardous mountain slopes in the State of Salzburg. Several significant historical rock fall episodes have been documented, and major expenditures have been made to construct retention basins and rock fall safety nets to mitigate risks associated with future slope failures.

Inhabited structures situated along the base of the Ingelsberg have been evacuated and residential/light commercial structures and associated infrastructure have been

judged to be potentially vulnerable to future slope failures [1].

The results of traditional slope monitoring, including several tachymetry prisms and fissure meters, have proved ambiguous in terms of revealing the overall slope behavior and failure process. To obtain further details regarding slope deformations and to illuminate slope failure characteristics, continuous real-time monitoring was performed from March 2013 through July, 2014 with a Ground Based Interferometric Synthetic Aperture Radar (GB-InSAR).

These measurements represent the first long-term GBInSAR measurements conducted in Austria. As enumerated herein, a cumulative data set of approximately 130,000 radar scans has been collected and analyzed to obtain significant insight regarding behavioral characteristics and geotechnical hazards.

2 The Ingelsberg in Bad Hofgastein, Austria The Ingelsberg is located approximately 70 km south of Salzburg along the northeastern margin of the village of Bad Hofgastein (Figure 1). Geologically the Ingelsberg is situated within Pennic Units of the Tauern window [3] [4], a major alpine geological feature characterized by an extensive dome-like structure. The Ingelsberg slope instability has lower and upper elevations of approximately 1,050 and 1,450 m, respectively. The slope inclination ranges from locally near-vertical in the head region to about 40° in the lower portion of the slope. As depicted in Figure 2a, a black phyllite unit comprises the base of the Ingelsberg,

Fig. 1. The Ingelsberg in Bad Hofgastein: a) location map [2]; b) geologic map (green = greenschist; blue = calcareous mica schist; brown = black phyllite; yellow = moraine material; triangles = landslide debris, modified after [3]

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D. S. Kieffer/G. Valentin/K. Unterberger · Continuous real-time slope monitoring of the Ingelsberg in Bad Hofgastein, Austria

Fig. 2. a) Schematic geologic cross section of the Ingelsberg, modified after [1]; b) characteristic blocky rock mass structure exposed in head area of the Ingelsberg (people within circle for scale)

which is overlain by greenschist with interbedded calcareous mica schist.

As shown schematically in Figure 2a, the schistosity dips gently into the hillside (toward the northeast), and the overall rock structure is characterized by steeply dipping to sub-vertical joints striking at both high and low angles to the hillslope orientation. Sheared and highly weathered zones have developed along the schistosity, resulting in a sequence of comparatively hard and soft interlayers. The joints and schistosity intersect to form a blocky rock mass structure, with moderately slender and vertically oriented prismatic columns commonly exposed in the slope face (Figure 2b). Ground fissures in the head area of the Ingelsberg have developed due to tensile separations between the steeply-dipping joints, and local speleologists have documented fissure widths and depths of up to 2 and 80 m, respectively [1]. Talus material locally blankets the bedrock in the mid to lower parts of the slope (particularly along topographic benches), and a prominent debris fan has developed at the toe of the Ingelsberg.

The Ingelsberg has experienced episodic slope instability, with several rock fall events having been documented as far back as the late 1700s. Based on historical accounts most events appear to have ranged from several tens to several hundreds of cubic meters in volume, with

the largest documented event of approximately 5,000 m3 occurring in 1987 [1].

3 Fundamentals of GB-InSAR Synthetic Aperture Radar (SAR) is an active microwave imaging system, involving transmission of electromagnetic radiation and recording of the reflected signal. The signal is recorded as a complex number, which includes both magnitude and phase information. The amplitude is related to the amount of energy contained in the backscattered signal, while the phase is dependent on the target-sensor distance [5]. With ground-based SAR, the radar aperture is synthetically enlarged by moving the antenna along a linear rail, while repeatedly transmitting and receiving microwaves from different positions.

InSAR is a methodology that uses phase interference from different data acquisitions to derive, through numerous processing steps, digital elevation models, displacement maps, and displacement time series. The InSAR principle for measuring a change in target-sensor distance is depicted in Figure 3a. The data acquisition geometry is related to the spatial resolution (pixel-size) of the SAR image, which can range from a few decimeters to several meters [6]. As shown in Figure 3b, the resolution is constant

Fig. 3. GB-InSAR principles: a) calculation of distance change based on microwave phase interference (TX = microwave transmitter; RX = microwave receiver; λ = wavelength; ϕ1 and ϕ2 = measured phase of reflected signal from first and second acquisitions, respectively); b) GB-InSAR acquisition geometry; c) acquisition geometry draped over irregular topography, modified after [7]

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in the cross-range direction, and in the range direction the resolution depends on target-sensor distance. A representation of the acquisition geometry draped over irregular topography is depicted in Figure 3c.

GB-InSAR refers to the acquisition of SAR imagery with ground-based instruments. According to [8] the theoretical accuracy of GB-InSAR is approximately +/–0.1 mm, which is typically reduced to a few tenths of mm to a few mm, depending on atmospheric conditions and the monitoring distance.

Detection of the precursor movements of slope failure necessary for making reliable time to failure projections requires continuous real-time monitoring information, and data that covers the entire slope at a high resolution is of particular value. Over the past 15 years significant advancement has been made in the development and application of GB-InSAR technologies to monitoring of hillslopes. Remote measurements up to a distance of 4km covering large domains can be made, providing comprehensive measurements with high spatial and temporal resolution. GB-InSAR surveys have the advantage of being largely independent of weather and light conditions, and have recently seen increasing deployment for slope failure prediction in civil engineering and mining applications [9].

4 GB-InSAR monitoring campaign The GB-InSAR campaign provided continuous monitoring data from March 27, 2013 until July 17, 2014. During this time period approximately 130,000 scans were collected with equipment having the specifications summarized in Table 1. The survey range of approximately 1.2 km correlates to an InSAR measurement cell dimension (pixel resolution) of 0.75m by 5.3 m in the range and cross-range directions, respectively.

Figure 4 shows the GB-InSAR hardware, together with the instrumentation shed for housing all instrumentation. A weather station was installed for collecting realtime data and all InSAR and climatic information were transmitted for office analysis via cellular router.

4.1 General displacement trends of the Ingelsberg An overview of the Ingelsberg slope together with the GBInSAR displacement map for the time period May 5, 2013 to July 17, 2014 are shown in Figure 5. The GB-InSAR results provide the component of total displacement that is parallel to the line-of-sight between the radar head and corresponding measurement cell. The results shown are for the unvegetated area of the Ingelsberg (heavy vegeta-

Tab. 1. Technical specifications of GB-InSAR campaign Time period

Phase 1 (27.03.2013–01.05.2013): 7,324 scans Phase 2 (03.05.2013–17.07.2014): 122,629 scans

Instrument

GB-InSAR model IBIS-FL (IDS Corp., Italy)

– frequency

17.1–17.3 GHz

– wavelength

17.44 mm

– scan time

5 to 7 min

– scan length (synthetic aperture)

2m

– maximum range

4,000 m

– range resolution

0.75 m

– cross-range resolution

4.4 mrad

– antenna beam width

50° horizontal; 20° vertical

Data processing

IBIS Guardian/Data Viewer (IDS Corp., Italy)

Climatic data (@ 15 min intervals)

Davis Vantage Vue weather station

Data transmission (field to office)

Cellular router

Fig. 4. a) IBIS FL GB-InSAR radar head and sliding rail; b) instrumentation shed for the GB-InSAR, weather station, and power supply and data transmission equipment

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Fig. 5. Left: overview of the Ingelsberg slope, with prior rock fall deposits encircled; right: GB-InSAR displacement map for the time period May 5, 2013 to July 17, 2014 (negative displacements indicate movement of the slope toward the radar sensor)

Fig. 6. Areas for which the displacement time histories of all included GB-InSAR measurement cells are averaged and plotted in Figure 7 (negative displacements indicate movement of the slope toward the radar sensor)

Fig. 7. Upper diagram: averaged displacement time histories for the time period May 5, 2013 to July 17, 2014 for the fan, bench, and rock wall areas shown in Figure 6 (positive displacements indicate slope displacements toward the radar); lower diagram: intensity of weekly precipitation recorded over same time period

tion has been filtered out). The displacement map indicates significant activity, with major portions of the slope having accumulated more than 500 mm of movement.

The areas of most significant movement occur beneath steep rock walls, along gently inclined topographic benches, and in a fan configuration near the base of the slope.

To further investigate displacement tendencies of the slope, three query areas were established as depicted in Figue 6. The areas “fan”, “bench”, and “rock wall” include debris fan deposits, slope talus, and a competent steep rock wall, respectively. Within each area, the displacement time histories of all included GB-InSAR measurement cells have been averaged and plotted in Figure 7, together with precipitation data.

Figure 7 indicates a concentration of activity within the debris fan at the toe of the slope, where maximum recorded displacements exceed 1,000 mm. Significant mobilization of talus material blanketing the mid to lower portions of the slope is also indicated, where maximum displacements approach 500 mm. Largely overshadowed by the significant fan and talus displacements are the gradually occurring permanent displacements of the upper rock wall, having reached a cumulative maximum magnitude of about 15 mm.

The intensity of recorded weekly precipitation shown in Figure 7 has a strong correlation to the displacement time history trends. Episodes of significant accelerating slope movements occur almost exclusively during periods

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of increased precipitation, with the effect becoming progressively dramatic toward the toe of the slope (i.e. from the rock wall to bench to fan).

May 2, 2013 is shown in Figure 8, along with an annotated photograph illustrating the rock fall event. The images are highly correlated in terms of the location of rock fall detachment and areas of debris accumulation.

4.2 Rock fall event of 29 April 2013 4.2.1 Time of failure based on projections of GB-InSAR data At 17:00 on April 29, 2013, rock fall activity was recorded at the Ingelsberg. Post-event field studies indicate a rock block having an approximate volume of 20 to 40 m³ detached from the head area, resulting in talus being deposited along well-defined debris tracks. The GB-InSAR displacement map for the time period April 17, 2013 to

Displacement time history plots of individual pixels for time period April 12-30, 2013 are shown in Figure 9. Within the rock fall detachment area, progressive loosening followed by acceleration of portions of the rock outcrop are measured in the days preceding the rock fall event.

Fig. 8. Rock fall event of April 29, 2013: left: GB-InSAR displacement map for the time period April 17, 2013 to May 2, 2013; right: rock fall source area and deposit distribution based on field studies

Fig. 9. Displacement time histories of individual measurement cells in the time period of April 12–30, 2013

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Displacement, velocity, and inverse velocity time history plots for GB-InSAR measurement cells located within the rock fall detachment area are shown in Figure 10 for the time period April 16 to 30, 2013. Approximately nine days prior to the rock fall the displacement rate began to increase, with a corresponding drop in the inverse of velocity. The displacement rates then progressively increased, approaching a vertical asymptote at the time of failure.

Following the approach of Fukuzono [10], inverse velocity plots of monitoring data in the days preceding failure are shown in Figure 11. The first, second, and third plots consider only data collected more than seven, five, and one day prior to failure, respectively. For each data set, linear projection of the most recently collected 1/v data to a zero value is made to estimate the time of failure.

As shown, with the time of failure being approached, the

Fig. 10. Displacement, velocity, and inverse velocity time histories for the time period April 16–30, 2013; vertical dashed lines represent time of rock fall failure

Fig. 11. Time of failure projections based on developing inverse velocity time history; linear data projections are shown in red and vertical dashed lines represent time of rock fall failure

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accuracy of the failure prediction increases, with the final projection correlating well to the actual time of failure.

Unfortunately it cannot be known a priori which projection is most representative, necessitating continual re-evaluation of the data as it is collected.

5 Discussion and conclusions The GB-InSAR data indicate significant slope activity, with major portions of the slope having accumulated more than 500 mm of movement. The areas of most significant movement occur beneath steep rock walls, along gently inclined topographic benches, and in a fan configuration at the base of the slope. Geological field investigations show that the areas of significant movement occur almost exclusively within the blanketing talus material and debris fan deposits. Largely overshadowed by the talus and debris fan displacements are very gradual displacements accumulating within the bold rock outcrop forming the head area of the Ingelsberg, which reached approximately 15mm over the course of the survey campaign.

Precipitation events have a very strong correlation to GB-InSAR displacement time histories. The talus and debris fan deposits are often near their angle of repose and in a delicate equilibrium state, and precipitation is very effective in mobilizing these deposits. The debris fan at the slope base, being the natural collection point for talus transported from above, is most strongly influenced by precipitation, followed by the talus deposits blanketing the mid to lower portions of the slope. Although the effect is comparatively attenuated, the influence of strong precipitation events can be distinguished in the displacement time history of the bold rock outcrop in the head area.

An initial glance at the GB-InSAR displacements might be alarming due to the extensive areas of high displacements. However, these displacements are occurring within shallow blanketing talus deposits and the debris fan deposits, which are considered non-threatening. The talus and fan deposits are highly reactive to climatic disturbances. These surficial deposits originate as localized rock fall events, most of which occur episodically in the head area. While similar slope displacement patterns are likely to occur in the future, GB-InSAR measurements of the upper rock wall suggest there remains a longer-term potential for very significant rock fall volumes from the head area, as very gradual displacements of the rock wall progressively accumulate.

The results of geologic field investigations combined with GB-InSAR monitoring suggest that the Ingelsberg is undergoing a long-term complex process of pseudo sheet failure. The failure process has stress relief via classical sheet failure [11] as its analog, but differing in that it occurs in layered rock masses having disparate deformability characteristics. The concept of this failure process is shown schematically in Figure 12. Stress relaxation and loosening of the rock mass over geologic time results in progressive deformation of soft layers, thereby setting up the potential for rotation, shearing, and tensile separations developing in the bounding harder layers. The soft interlayers correspond to the sheared and weathered zones within the calcareous mica schist and greenschist rock units. The failure process leads to long-term progressive

Fig. 12. Schematic process of pseudo-sheet failure of the Ingelsberg

collapse of the frontal blocks, much like the characteristics of a calving glacier.

Following the approach of Fukuzono [10], inverse velocity plots of monitoring data were made for GB-InSAR measurements collected in the days preceding a small rock fall event which occurred on April 29, 2013. As the time of failure is approached, 1/v plots show a clear progression toward rapid failure, and the accuracy of the failure predictions increases as the most contemporary data is considered. Many 1/v projections can be made from the developing data, but it cannot be known a priori which projection is most representative. As emphasized by Rose and Hungr [12], monitoring must be continued as long as possible prior to failure, and the results must be constantly re-evaluated. The time of failure prediction approach of [10] is generally considered applicable to large landslides where ductile deformations/creep often precedes failure.

In situations involving brittle rock failure in tension or shear, and in particular cases at low stress levels that are characteristic of smaller failures, timing of failure estimates based on displacement monitoring results have been considered unfounded [12]. However, experience from the recent GB-InSAR campaign sheds doubt on this premise, as displacement plots provide clear early warning of the impending failure of a 20 to 40 m3 essentially rigid block.

References [1] Wilhelmstötter, F.: Geotechnisch-Geologische Untersuchung des Felssturzgebietes Ingelsberg/Bad Hofgastein. MS Thesis, Institute of Soil Mechanics and Foundation Engineering, Technical University of Graz, Austria, Unpublished, 2013.

[2] http://www.zonu.com/fullsize-en/2011-06-30-13993/Topographic-map-of-Austria-2008.html [3] Geologischen Bundesanstalt: Geologische Karte der Umgebung von Gastein, scale 1:50,000, Bundesamt für Eich- u. Vermessungswesen, 1956.

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[4] Schmid, S. M., Fügenschuh, B., Kissling, E., Schuster, R.: Tectonic map and overtall architecture of the Alpine orogen.

Eclogae Geologicae Helvetiae 97 (2004), pp. 93–117.

[5] Antonello, G., Casagli, N., Farina, P., Leva, D., Nico, G., Sieber, A. J., Tarchi, D.: Ground-based SAR interferometry for monitoring mass movements. Landslides 1 (2004), pp.

21–28.

[6] Mazzanti, P., Brunetti, A.: Assessing rockfall susceptibility

by Terrestrial SAR Interferometry. Proceedings of the Mountain Risks International Conference, 109–114. Firenze, 2010.

[7] IDS (Ingegneria dei Sistemi S. p. A.): Kinematics of the Slumgullion Landslide revealed by Ground based InSAR Surveys (prepared by Giorgio Barsacchi). 2011.

[8] Mazzanti, P.: Displacement Monitoring by Terrestrial SAR Interferometry for Geotechnical Purposes. Geotechnical Instrumentation News 25–28. 2011.

[9] Atzeni, C., Barla, M., Pieraccini, M., Antolini, F.: Early Warning Monitoring of Natural and Engineered Slopes with Ground-Based Synthetic-Aperture Radar. Rock Mech Rock Eng (2015) 48, pp. 235–246.

[10] Fukuzono, T.: A new method for predicting the failure time of a slope. In: Proc 4th Int Conf and Field Workshop on Landslides, pp. 145–150. Tokyo, Tokyo University Press, 1985.

[11] Goodman, R. E., Kieffer, D. S.: Behavior of rock in slopes.

Journal of Geotech and Geoenv Eng 126 (2000), No. 8, 675–684.

[12] Rose, N. D., Hungr, O.: Forecasting potential rock slope failure in open pit mines using the inverse-velocity method.

Int Journal Rock Mech Min Sci 44 (2007), pp. 308–320.

Univ.-Prof. D. Scott Kieffer, Ph.D., P.E., C.E.G. Graz University of Technology Institute of Applied Geosciences Rechbauerstraße 12 8010 Graz Austria kieffer@tugraz.at

Mag. Gerald Valentin State of Salzburg Geological Survey Michael Pacher Straße 36 5020 Salzburg Austria gerald.valentin@salzburg.gv.at

M.Sc. Klaus Unterberger hbpm Ingenieure GmbH Wolf 32 6150 Steinach am Brenner Austria klaus.unterberger@hbpm.it

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Topics Andreas Gaich Gerald Pischinger

DOI: 10.1002/geot.201500048

3D images for digital geological mapping Focussing on conventional tunnelling 3D images combine visual and geometric information making them an obvious source for capturing and characterising rock surfaces especially when there are constrained time and access conditions. By taking photographs with an off-the-shelf camera and using modern algorithms from photogrammetry, 3D imaging has become state of the art on many conventional tunnel construction sites. Data is acquired on a daily basis, processed, geologically assessed, and finally stored in a suitable data base. The contribution provides a brief introduction of the technology and its measurement capabilities, as well as a description of the practical application during the construction of the 8 km long Gleinalmtunnel in Austria.

1 Introduction In 2006, the American Rock Mechanics Association (ARMA) hosted a workshop entitled: “Laser and Photogrammetric methods for rock face characterization”. The workshop aimed at bringing together the manufacturers and early users of upcoming systems for digital rock mass characterization. Special focus was given on geological mapping, hence a practical field exercise was performed. Systems and their results were compared, and general conclusions were derived. The major conclusion as given in the workshop report [1] reads: “The obtained results indicate that digital photogrammetry yields reliable and reproducible results when applied to rock mass characterization. Digital photogrammetry is thus a mature enough technology that can be used with confidence in the profession provided care is taken to follow the guidelines provided by the presenters in this report.”

Although available since then, it took several more years before the technology became standard practice on conventional tunnelling sites. Now in 2015, all larger tunnel projects in Austria with conventional excavation use 3D imaging for the acquisition of the tunnel face conditions and geological mapping. Reasons for the application of the technology may be found in the abilities and characteristics of 3D imaging including: – Measurement of inaccessible areas, – Enhanced safety on site (no personnel in rock fall areas), – Quick change of perspective and zoom (better understanding of large features), – Permanent documentation of rock mass conditions and excavation stages, – Objective data basis for contractual-legal issues.

This contribution provides some introductory information about the technology and the practical application of 3D imaging on a conventional tunnelling site.

2 3D image generation A 3D image combines three-dimensional surface data with digital imagery to a consistent three-dimensional model.

To extract the 3D surface data one needs at least two photographs of the same scene taken from different angles.

This principle is called Shape-from-Stereo and is shown in Figure 1. A pair of corresponding (identical) image points P(u,v) is connected with corresponding projection centres O(X,Y,Z). The intersection of these two rays gives a threedimensional surface point P(X,Y,Z). The underlying principles originated from Photogrammetry [2] and were later extended by findings from Computer Vision [3] that allowed the use of off-the-shelf cameras and provided algorithms that were designed for a processing digital imagery quickly.

In the 2000s, extensions were introduced including the so-called Structure-from-Motion technique. The motivation was to reconstruct architectural models from a large set of unordered photographs and to combine them into a single, consistent 3D model [4]. The basic idea was to use a high degree of redundancy for an automatic com-

Fig. 1. Shape from Stereo principle

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A. Gaich/G. Pischinger · 3D images for digital geological mapping

Fig. 2. Automatically computed arrangement of eleven images using some thousand tie points, i.e. points seen on several photos that are used for inter-linking the images

Fig. 4. Data acquisition at a conventional tunnel construction site

seen as supplement to a conventional data acquisition rather than a substitute, as feared at earlier days of the technology.

In order to get 3D images, photos need proper quality. Hence they are usually taken from a tripod in order to cope with low light conditions. At least two photos of the face are taken from two different locations. Figure 4 shows an example for the data acquisition at a conventional tunnelling site. Photos are taken with a pre-calibrated off-theshelf SLR camera.

Fig. 3. The resulting 3D image combines a dense point cloud with a geometric surface description and digital photographs

putation that usually followed a sequence of operations, often referred to as the structure from motion pipeline.

A key component inside the structure from motion pipeline is to determine the individual camera locations for the overall arrangement – also known as Bundle Adjustment. Besides its ability to simultaneously compute the camera locations, it also computes camera calibration parameters in the same step on demand (autocalibration).

Figure 2 shows the result after the determination of the camera positions and orientation (arrangement). Surface points act as tie points between the photographs, the small pyramids represent the camera locations. Figure 3 shows an example of a resulting 3D image.

3 Application in conventional tunnelling Tunnel construction sites with conventional excavation usually include two disadvantageous conditions for geological data acquisition: – The need for physical contact, – The little amount of time available in front of the face.

When using 3D images, geometric rock mass information is captured quickly, so more time remains for the assessment of non-geometric phenomena of the rock mass, e.g. water ingress, the amount and quality of discontinuity fillings (which needs physical contact), or a qualitative judgement on the rock mass behaviour. Thus, 3D images are

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3.1 Measurement possibilities Photos are processed by a designated software and a 3D image is computed within few minutes. The 3D images are then used to perform geologic mapping using a purposebuilt 3D software component. For geometric rock mass characterization the following measurement possibilities are included: – Orientation, location, size, and shape of visible discontinuity surfaces, – Orientation, location, and length of fracture traces or strata, – Distances, areas, volumes (e.g. of overbreaks), – Roughness (by profiles).

Besides, arbitrary sections and elevation maps can be visualized.

Figure 5 shows the 3D image of a tunnel face (top heading) with a resulting structural analysis as provided by the geologist on site. Several graphical elements are available which can be grouped into (discontinuity) sets and be displayed as overlays on top of the 3D image. From the geometric measurements descriptive rock mass parameters are directly derived including: – Number of joint sets (user defined joint sets or automatic determination of joint sets through orientation clustering), – Statistics on mean orientations and spatial variation of joint orientations, – Joint spacing of projected trace maps (normal spacing including statistical parameters), – Spacing along arbitrary scanlines (normal, apparent, total spacing including statistical parameters),

A. Gaich/G. Pischinger · 3D images for digital geological mapping

Fig. 5. 3D image of a tunnel face including plot of the major rock structures displayed as graphical overlay

Fig. 7. Tablet computer for mapping instantly on digital photographs

This has the potential to replace manual analogue sketches and shall be further extended in order to include all information that is currently captured by an attentive geologist.

4 Case study: Application at a hard rock tunnel site 4.1 Project area

Fig. 6. Stereonet of a tunnel face assessment (left); joint spacing analysis of a projected trace map (right)

– Joint persistence using the size of joints and bridges (unfractured rock between traces) including statistical parameters, – Assessment of joint termination, – Graphical output of spacing and orientation measurements (Figure 6), – Visualization of the topography of the tunnel face.

Additional functionality using mapped features include: – Statistics on spacing over one or several joint sets, – Automatic clustering of joint orientations, – Statistics on the spatial variation of joint orientations, – Statistics on the length of joint traces and bridges.

3.2 Using a mobile mapping device Above mentioned procedures allows the geologists to do their mapping off site. In order to improve mapping on site a tablet computer is used where photos of the tunnel face are instantly provided to the geologist. All relevant structures can be marked quickly as graphical annotations to the photos. Later, during processing the photos to a 3D image, all structures are upgraded to 3D. This way: – Drawings are in correct scale and relationship, – No additional digitization of analogue sketches is required.

From December 2013 to March 2015, 3D imaging and digital mapping were used for the geological documentation of the second tube of the Gleinalmtunnel. This more than 8 km long tunnel is part of the A9 motorway, which is one of Austria’s main north-south connections leading through the Eastern Alps. The geology of this tunnel is characterized by gneisses and amphibolites with uniaxial compressive strengths (UCS) often exceeding 100 MPa. Laboratory tests show maximum UCS values of more than 230 MPa. The rock mass is characterized by a pronounced discontinuity pattern. However, discontinuities are frequently healed by mineral infillings. As the rock mass conditions are predominantly favourable, it was decided to excavate large parts of the tunnel using full face excavation and round lengths of up to 3.5 m. Tunnel cross section in full face excavation was approximately 90 m², with a width of 11 m and a height of 9 m. In total 836 3D models were calculated for geological mapping purposes of the two main headings (approximately one every 10 m).

4.2 Data acquisition Photos for the 3D models were taken by a calibrated camera system (Canon Eos 7D and a Sigma EX 10 to 20 mm lens). Light, as provided by the contractor, varied from a complete dark to well illuminated conditions. In the first (the rarer) case battery powered floodlights were used to achieve adequate lighting. Image acquisition worked well even in low light conditions as long as the light conditions were constant (i.e. did not vary from moving vehicle lights or torches). In the majority of cases images were taken directly after mucking and, depending on which working step followed, the shotcrete machine or the drilling jumbo were used to illuminate the tunnel face area.

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Fig. 8. Scaling and referencing: (a) range pole, (b) LightScale, (c) projected laser dot pattern on the tunnel face (denoted by white circle and arrow

For the bench heading, the sidewalls and the face were usually photographed separately and the individual models were merged into a single model for geological mapping (see Figure 10). For merging the models, the individual models need sufficient overlap (about 25 %) to allow for successful merging.

4.3 Scaling and referencing Referencing and scaling of the 3D image was done using three different methods. For the simplest and most often applied method a “range pole” was used (Figure 8a) with two discs at known distance. The range pole was placed and vertically aligned next to the newly blasted round in an area already secured by shotcrete and bolts. The resulting models were then referenced with respect to the geographic north by rotating the tunnel face into the direction defined by the azimuth of the tunnel heading.

The second method consisted of scaling and referencing by means of a laser projection unit called “LightScale” (Figure 8b), which projects four laser dots onto the tunnel face (Figure 8c). The left and the right laser are horizontally adjusted with the help of the integrated water level.

All four laser beams are parallel to each other, with a defined distance between the beams. The orientation of the laser beams is determined by the combined information from an integrated electronic compass and an electronic

Fig. 9. Scaling and referencing with target poles that were conventionally surveyed

inclinometer. The values provided by these instruments are used for the orientation of the 3D model. Attention has to be paid that the compass readings are not distorted due to electromagnetic fields of nearby machines. The tripod and LightScale together have a weight of approximately 8 kg. The LightScale was especially useful when the range pole could not be positioned near the tunnel face. For example, it was used in the ventilation caverns,

Fig. 10. Merged model of bench excavation

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A. Gaich/G. Pischinger 路 3D images for digital geological mapping

Fig. 11. Schematic work flow of geological documentation at the Gleinalmtunnel site

where a second, inaccessible top heading was excavated after making the lower part of the cavern. Deviation of magnetic north from geographic north was taken into account when referencing the model. In the project area, this deviation is approximately 3掳.

The third method used surveyed control points. In the case of the Gleinalmtunnel this was accomplished with the help of targets that were installed by the contractor and measured by surveyors for profile control with their theodolite (Figure 9). As long as at least three of these points were visible on the photographs, their coordinates were sufficient to referenc and scale the 3D image.

When merging models (e.g. for bench heading), the reference points (RangePole, LightScale, or 3D surveyed points) have to be visible only in one imaged section (the master model).

4.4 Analog and digital geological mapping According to the experience and records related to the construction of the first tube, rock mass conditions with very strong rocks (UCS > 100 MPa) and discontinuity controlled excavation behaviour were predicted for the second tube. Therefore, geological mapping focused especially on the detection and mapping of discontinuities and their properties. Generally the geological documentation followed the guideline for geotechnical design of underground structures with conventional excavation [5] and aimed at documenting the relevant parameters specified during the design stage.

The schematic workflow of geological documentation in conjunction with 3D imaging and digital mapping is shown in Figure 11. It included a manual sketch of the main geological features of the tunnel face (e.g. lithological boundaries, foliation, discontinuities, folds, and faults).

The lithologies and their basic properties were addressed

directly at the tunnel face by carrying out observations and simple field tests according to ISRM suggested methods and EN-ISO 14689-1. Also, both the rock mass behaviour and discontinuity control of the excavation geometries were addressed directly at the tunnel face. Work in the tunnel was accomplished by taking photos for the 3D model and, if considered necessary, by taking additional pictures (e.g. details of geological structures or of excavation) with a regular digital camera. The time span needed to accomplish the work at the tunnel face depends on the available time window (usually less than 10 min). Time needed to acquire the photos for the 3D model was usually significantly less than 3 min. Part of the geological mapping at the tunnel face was usually done parallel to other works (bolting, mucking, spraying concrete, drilling, maintenance works). Usually mapping followed directly the mucking procedure. So the overall time needed for geological mapping and picture acquisition varied between 10 and 30 min.

Digital geological mapping consisted primarily of mapping discontinuities and their orientations (Figure 12). Mapped discontinuities were usually grouped into sets by the cluster algorithm implemented in the used assessment software [6] and edited manually for erroneously assigned measurements. The field sketch of the tunnel face was updated by comparing it with the scaled 3D model and adding orientation values in order to obtain a more precise face map (discontinuities, lithological borders, geometrical constraints).

Besides, the field estimates of discontinuity spacings were compared to and corrected with distance measurements done on the 3D model.

Cross sections were extracted in order to assess the influence of discontinuities on the excavation geometry (see Figure 7). In addition, further data such as the round length, the location and length of blast hole remnants were measured from the 3D images.

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Fig. 12. Digital mapping of a top heading – (a) picture pair used for (b) calculation of the 3D model, (c) mapping of discontinuities and (d) directional statistics, as well as for extraction of profiles (e), (f)

Fig. 13. Import of discontinuity data to the geological database: Spreadsheet of discontinuity data exported from 3D model (left side) and import window of the geological data base (right side)

4.5 3D image for communication purposes After completion of the mapping process, both the 3D model and the structure map were uploaded on the secure site server. This happened on a daily basis and allowed for a prompt and reproducible description of the actual geological conditions. In case of suspected or obvious geological hazards, the responsible people were informed and the 3D model was used to explain the situation to the geotechnical engineer as well as to the site supervisors and the engineers from the contractor.

well as descriptions of the encountered geological, hydrogeological and geotechnical conditions. Reports of the documented rounds were prepared in the data base and provided on a daily basis to the involved parties. Further, the data base allows for a statistical evaluation of the documented parameters (geotechnical parameters, lithologies). The drawing of geological sections is supported by export functions.

In order to facilitate the workflow, data exchange routines were provided to allow for a smooth flow of information between the digital mapping results and the geological data base (Figure 13).

4.6 Integration of data into a geological database 5 Conclusions The acquired information of each assessed round was stored in a geological data base. This data included the hand sketch of the tunnel face, photos, samples taken, as

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As Hoek [7] wrote, engineering geological work should be led “by sound geological reasoning and rigorous engineer-

A. Gaich/G. Pischinger · 3D images for digital geological mapping

ing logic rather than by the very attractive images that appear on the computer screen” with the overall goal of “putting numbers to geology”. In this context, 3D images provide the opportunity to put numbers at least to certain aspects of geology.

3D images are automatically generated from a large set of unordered photographs using modern image matching algorithms. They serve as self-explaining documentation of rock surfaces and allow for digital geological mapping in a comprehensive manner. Several tools for determining rock mass parameters are available. The acquired results also serve as basis for tunnel stability estimation and for making decisions about support measures.

At the construction site of the Gleinalmtunnel, more than 800 excavation rounds were documented using a commercially available 3D imaging solution. Photogrammetry based mapping of rock surfaces exposed during tunnel excavation confirmed to be a valuable tool in obtaining reproducible high quality geological data. In addition, the 3D models were used for explaining and discussing the geological and geotechnical situation with the involved parties (e.g. client, site supervision, geotechnical engineer, and contractor).

The successful application of 3D imaging during tunnel excavation requires a sound understanding of the technology and acceptance at the tunnel site. This is best achieved by providing adequate contractual frameworks on the one hand (who does the pictures, who provides the light, who is responsible for digital mapping) and on the other hand by providing to the parties involved at the tunnel site in due time the information and instructions necessary (what is done why and when, what is needed).

3D images support the communication of the geological/geotechnical conditions and provide objective data which might be very helpful in case of contractual-legal issues. Finally data acquisition such as 3D imaging during tunnel excavation substantially increases safety of the onsite geologists.

References [1] Tonon, F., Kottenstette, J: Laser and Photogrammetric Methods for Rock Face Characterization, Report on a workshop in Golden, Colorado in conjunction with the Golden Rocks Symposium, 2006.

[2] Slama, Ch. C. (ed.): Manual of Photogrammetry. 4th edition. American Society of Photogrammetry, Falls Church, 1980.

[3] Hartley, R., Zisserman, A.: Multiple View Geometry in Computer Vision. Cam-bridge University Press, 2001.

[4] Snavely, N., Seitz, S.M., Szeliski, R.: Modeling the World from Internet Photo Collections. International Journal of Computer Vision 80 (2008), No. 2, pp. 189–210.

[5] Austrian Society for Geomechanics: Guideline for the Geotechnical Design of Underground Structures with Conventional Excavation – Ground characterization and coherent procedure for the determination of excavation and support during design and construction. Salzburg, 2010. Retrieved May 11, 2015, from http://www.oegg.at/en/service-8/download-28/ [6] 3GSM GmbH: ShapeMetriX3D Manual for version 3.8.

Graz, 2014.

[7] Hoek, E.: Putting numbers to geology – an engineer’s viewpoint. Quarterly Journal of Engineering Geology, 32 (1999), No. 1, pp. 1–19, 1999.

Andreas Gaich 3GSM GmbH Plüddemanngasse 77 A-8010 Graz Austria a.gaich@3gsm.at

Gerald Pischinger Geoconsult ZT GmbH Hölzlstraße 5 5071 Wals bei Salzburg Austria gerald.pischinger@geoconsult.eu

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Topics Johannes Horner Andrés Naranjo Jonas Weil

DOI: 10.1002/geot.201500046

Digital data acquisition and 3D structural modelling for mining and civil engineering – the La Colosa gold mining project, Colombia Digital data acquisition, data management and 3D modelling techniques are common techniques in the mining industry. On the other hand, civil engineering projects still lag behind in applying advanced technologies during geological reconnaissance and investigation. The La Colosa gold mining project (Colombia) is presented as an example, where sophisticated digital mapping techniques and 3D geological modelling is not only used for mining related issues, but is also successfully applied for the geological, geotechnical and hydrogeological investigations of adjacent civil engineering sites of the associated mine infrastructure.

1 Introduction Large-scale mining and infrastructure projects are, in general, characterized by a number of geological, geologicalgeotechnical, and hydrogeological investigation phases.

The principal objective of all these investigation phases is to acquire either new data on areas lacking sufficient information or to gain more detailed information, in order to increase the level of knowledge of specific conditions.

At large-scale mining projects, the geological, geotechnical and hydrogeologic data are usually acquired, stored, handled and analysed by means of highly advanced digital technologies. In contrast, many civil engineering projects, independent of size, still lack the application of advanced digital data acquisition, data storage and 3D modelling techniques. Reasons for this difference seem to be manifold. However, one important reason is the fact that at mining projects the ground represents value which has to be explored, exploited and sold with profit, whereas at civil engineering projects the ground is commonly considered as an obstacle, which has to be removed or stabilized at a low cost. In consequence, it is often the economic factor which promotes or hampers the application of state-of-the art technologies for geological data acquisition, data management, and visualization.

The world-class La Colosa gold mining project is presented as an example of how digital mapping and data acquisition technologies are used to define geological structures for the planned open pit as well as for the adjacent infrastructure areas.

2 The La Colosa gold mining project The La Colosa open pit gold mining project, owned and developed by AngloGold Ashanti, is located in the high

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Andes of the Central Cordillera of Colombia (approx.

2,600 to 3,200 m elevation), approximately 40 km to the west of the City of Ibagué, Department of Tolima (Figure 1 and Figure 2). Since the start of exploration activities in 2006 [1] up to July 2015, a total of 414 diamond drill holes of a total length of 141,230 m have been drilled. The current mineral resource estimation gives a combined indicated and inferred mineral resource of 33.15 m. ounces of gold (1,030 Mt of ore at a grade of 0.82 g/t gold) [2]. Based on this resource estimate, the La Colosa project will become the largest gold deposit in the Northern Andes.

Currently, the project is in the pre-feasibility stage. According to the preliminary design of the planned open pit mine, the final pit outline will reach about 2.5 km in N-S direction and 1.5 km in W-E direction. The south-facing wall of the open pit will reach a final height of approximately 820 m.

The associated mine infrastructure includes sites for the crusher, plant and workshops, waste rock and tailings sites, as well as water control and water treatment facilities. This involves the design of large-scale civil engineering structures such as dam structures, high slope cuts, landfill, and tunnels. The area of the associated mine infrastructure straddles the eastern part of the 8.65 km long La Línea tunnel (see Figure 1).

3 Geological frame The La Colosa deposit is located in the Central Cordillera and is associated with an intrusive complex of Miocene age, which consists of three major magmatic pulses (see Figure 1). This intrusive complex was emplaced into the Triassic (to most probably Jurassic) basement rocks of the Cajamarca Complex which underwent polyphase deformation and metamorphism during Andean orogenic processes [3]. Contact metamorphism during emplacement of the intrusive stock caused the formation of hornfels.

Based on a detailed structural study of the area, the following deformation events can be distinguished (Figure 3) [4]: – Deformation event D1 is characterized by a closed, subvertical to slightly west-vergent folding with a penetrative NNE- to NNW-trending schistosity (s1). Fold axes (b1) plunge sub-horizontally to the N and S. E- to ESEdipping ductile shear zones commonly represent axial surface planes.

© 2016 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin · Geomechanics and Tunnelling 9 (2016), No. 1

J. Horner/A. Naranjo/J. Weil ¡ Digital data acquisition and 3D structural modelling for mining and civil engineering â&#x20AC;&#x201C; the La Colosa gold mining project, Colombia

Fig. 1. Geological map La Colosa project

Fig. 2. Overview La Colosa project, view to east (La Colosa ridge), infrastructure areas in foreground

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Fig. 3. Deformation history, La Colosa project (modified from [4])

– Deformation event D2 overprints D1 and is characterized by the formation of open folds with E- to SE-plunging fold axes (b2) and sub-horizontal schistosity (s2).

– Ductile deformation events D1 and D2 can be correlated with compressional tectonics of the Andean orogeny, when slices of oceanic crust of the Pacific realm accreted to the northwestern margin of South America along regional N- to NE trending, right-lateral suture zones.

– Continued deformation and uplift of the Central Cordillera marked the transition from a ductile to a brittle environment. Regional fault zones, including the NNE-trending Palestina Fault System, were reactivated changing the shear sense from right-lateral to left-lateral.

The new stress field (deformation event D3), with compressional forces shifting from a W-E direction to NWSE direction, was triggered by the eastward migration of the Caribbean Plate in the Miocene. The new tectonic environment caused the development of new secondary structures, including W- to WNW-striking faults, and the reactivation of previously formed N-trending structures within the broad Palestina Fault System. In general, brittle structures show extensional characteristics control-

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ling the emplacement of the magmatic complex at La Colosa.

4 Data types, data acquisition and handling At the La Colosa project, like in exploration projects in general, many different types of data are collected, including geological, geochemical, mineralogical, structural, geophysical, rock mechanical and hydrogeological data. An overview of the most important data types is given in Table 1. The principal purpose of the extensive data acquisition is to accurately portray the greatest possible knowledge regarding the geological, hydrogeological and geotechnical conditions of the mineral deposit, in order to minimize any technical and, in consequence, economic risk for the project.

Data are acquired directly in the field during field mapping (geology, structures), during in-situ testing (down-hole geophysics; hydrogeology), by drill core logging (geology, mineralogy, structures, rock mechanics), and during subsequent laboratory analysis (geochemistry) and testing (rock and soil mechanics, metallurgy and comminution) of selected drill core samples.

J. Horner/A. Naranjo/J. Weil · Digital data acquisition and 3D structural modelling for mining and civil engineering – the La Colosa gold mining project, Colombia

Table 1. Types of data acquired at the La Colosa project

Some types of data are acquired in the field by means of analogue processes, including geological field mapping and geological drill core logging data. Other types of data are obtained directly in digital format, including geophysical bore-hole scanning data, hyperspectral drill core analysis, hydrogeological data from piezometers and groundwater monitoring points, geochemical data, and laboratory testing data.

During the various exploration stages of the project, several data acquisition techniques were modified and adjusted, in order to increase the effectiveness of work procedures and to enhance data quality and data reliability.

In the course of this process, the acquisition of structural field data was also adjusted from manual mapping in conjunction with a hardbound field book towards a digital solution (Figure 4). A new tool was applied using a rugged tablet. A portable GIS solution (Fieldmove) [5] allowed direct mapping of structural elements, such as foliation, fold axes, faults and fracture zones, on a digital base map. The portable GIS also enabled the import and use of additional information (e.g. geological data, design of existing and planned infrastructure), which helped in guiding field mapping. Acquired structural data were exported and stored on a daily basis and were readily available for subsequent analysis and 3D visualization.

Concerns regarding the use and performance of a tablet in the difficult topographical and climatic conditions of the project area could be alleviated. After getting through a learning period, advantages of digital mapping prevailed, such as real-time verification of location points

Fig. 4. Digital data acquisition by using a rugged tablet

and structural data sets, switching of scales due to independency using the portable GIS, and the time-saving performance during data import and data export.

Data handling and administration is crucial for an exploration and mining project when big amount of data have to be readily available for reviews, cross analyses, interpretations and estimations. At the La Colosa project, all data, acquired by field mapping, drill core logging, downhole surveying, and laboratory test work, are integrated into and administrated by a geological data base (Figure 5).

This data base is constantly updated as newly acquired data enter daily. The data base is also subject to adjustments and extensions while the application of new techniques and new testing methods generate new data sets, which have to be administrated in a logical and structured way.

5 3D modelling of geological structures The spatial analysis of the acquired structural data was performed directly in a 3D environment (Leapfrog Geo/Leapfrog Mining) [6]. The 3D visualization of the structural elements enables a fast and effective analysis and interpretation of the spatial relation of the structural features. Structural surface data can be displayed, analysed and interpreted in combination with drill core logging data and bore-hole scanning data, as well as any other data type that include information about structures (e.g. hydrothermal alteration, geochemistry, hydrogeological data, geophysical data).

For the La Colosa project folds of the deformation events D1 and D2 as well as brittle faults of deformation event D3 were modelled using data from surface structural mapping, drill core logging, bore-hole scanning, and also from hydrogeological monitoring (Figure 6).

Folds were modelled using surface data including foliation (s1, s2), fold axes (b1, b2), and ductile shear zones (sh). Bore-hole scanning data and structural data from oriented drilling were used as supplementary sources of information, enabling the structural interpretation and modelling towards depth.

Brittle structures, such as faults and associated fracture zones were modelled using surface data and selected drill core logging data, including drilling intersections with logged fault zones, low RQD, low drill core recovery, and a high fracture frequency (FF). Only faults with a significant persistence (interpreted length > 400 m) were modelled.

Some faults are only constrained by a few outcrop points, whereas other fault planes could be modelled by linking

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J. Horner/A. Naranjo/J. Weil ¡ Digital data acquisition and 3D structural modelling for mining and civil engineering â&#x20AC;&#x201C; the La Colosa gold mining project, Colombia

Fig. 5. Geological data management at the La Colosa project

Fig. 6. 3D Structural model, La Colosa project (Section 493000 N; looking north)

surface outcrop data with drill core intercepts. It should be noted that a profound understanding of the drill core logging process is imperative, in order to be able to interpret and link specific drill core intercepts of faults and fracture zones with structural data from surface mapping.

Field observations from surface mapping such as shear sense of faults and cross cutting relationships are highly important, in order to obtain a consistent tectonicstructural interpretation.

The current 3D structural model covers an area of approximately 45 km2. The model is based on more than 2,500 structural data from a total of about 750 surface outcrop points, and information from more than 141,000 m of drill core. It defines the geometrical relationship of the ductile folds and shear zones as well as brittle faults.

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6 Implications for engineering and design At the planned La Colosa open pit, the high wall will reach a height of approximately 820 m. In consequence, the 3D structural model is essential for the geotechnical design of the pit slopes as major structures may control the stability at inter-ramp and global scale [7] [8].

By extending the existing 3D structural model towards the planned mine infrastructure areas important information for further geotechnical and hydrogeological investigation and subsequent engineering can be obtained.

The 3D structural model is currently used for the design of a hydrogeological and a geotechnical investigation programme covering the various infrastructure sites. In addition, the structural model in combination with the litho-

J. Horner/A. Naranjo/J. Weil · Digital data acquisition and 3D structural modelling for mining and civil engineering – the La Colosa gold mining project, Colombia

logical model guides the investigation programme for borrow materials, which are needed for the construction of the civil structures.

Subsequently, the 3D structural-lithological model will be used for rock mass characterization, rock mass modelling and geotechnical analysis for civil structures to be designed.

7 Conclusions and future steps In contrast to many civil engineering projects, the vast majority of exploration and mining companies have identified the need for digital mapping techniques, systematic data management, and advanced 3D modelling.

For an exploration and mining project a well-structured and efficient data management is essential, in order to guarantee a high level of data reliability and data availability. Data sets obtained by many different methods and processes have to be integrated, stored and administrated for complex analysis and estimation processes. The immense volume of data obtained from different methods during the exploration process requires adequate tools for the management, the analysis and the interpretation of the collected data.

At the La Colosa gold mining project, a structural model was developed using digital acquisition tools and advanced 3D modelling techniques. Based on the structural geological observations from surface and drill core, a consistent structural model could be elaborated. This detailed structural model is a prerequisite for the elaboration of a geotechnical model. The current 3D structural model, which extends from the planned pit area towards the adjacent infrastructure areas, will serve as basis for subsequent hydrogeological and geotechnical studies for engineering and design of the open pit, and the associated mine infrastructure.

Acknowledgements The authors thank AngloGold Ashanti for giving permission to publish this paper. The numerous discussions in the field with the site geologists are gratefully acknowledged and have guided the development of our current understanding of this world-class mining project.

References [1] Lodder, C., Padilla, R., Shaw, R., Garzón, T., Palacio, E., Jahoda, R.: Discovery history of the La Colosa gold porphyry

deposit, Cajamarca, Colombia. Society of Economic Geologists Special Publication Series, v. 15: 19–28, 2010.

[2] Anglogold Ashanti: Mineral Resource and Ore Reserve Report 2014 (http://www.aga-reports.com/14/ir/) [3] Villagomez, D., Spikings, R.: Thermochronology and tectonics of the Central and Western Cordilleras of Colombia: Early Cretaceous-Tertiary evolution of the Northern Andes.

Lithos, v. 160-161: 228–249, 2013.

[4] Naranjo, A., Horner, J., Castro, A., Uribe, A., Weil, J., Nugus, M.: La Colosa Au-porphyry deposit, Colombia: new insights on the structural control and ore-forming processes in the Northern Andes. Society of Economic Geologists, Hobart, Tasmania, 2015.

[5] Midland Valley:: Fieldmove. http://www.mve.com/digitalmapping_(accessed January 2016) [6] Aranz Geo Ltd.: Leapfrog Mining/Leapfrog Geo. http://www.leapfrog3d.com_(accessed January 2016) [7] Read, J., Stacey, P. (eds.): Guidelines for open pit slope design. CSIRO Publishing, 2009.

[8] Horner, J., Weil, J., Betancourt, J., Naranjo, A., Montoya, P.; Sanchez, J.: Rock mass and structural modeling for the large open pit gold mining project in the Northern Andes: The La Colosa Project, Colombia. In Dight (ed.): Slope Stability. pp.

127–136. Australian Centre for Geomechanics, Brisbane 2013.

Dr. Johannes Horner iC consulenten ZT GesmbH Zollhausweg1 5101 Bergheim Austria j.horner@ic-group.org

Andrés Naranjo AngloGold Ashanti Colombia Ibagué Colombia

Jonas Weil iC consulenten ZT GesmbH Zollhausweg1 5101 Bergheim Austria

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Product Information DSI delivers support materials for the Gemeinschaftskraftwerk Inn The Gemeinschaftskraftwerk Inn (GKI) – a collaborative project of the Tiroler Wasserkraft AG, the Engadiner Kraftwerke AG and the Verbund AG – is a large new run of the river power station being constructed on the upper River Inn in the border area between the Swiss village of Valsot and the Austrian village of Prutz. The power station, which has been extensively checked in Austria and Switzerland, will generate about 400 GWh of hydropower electricity annually after the construction phase (2014 to 2018).

The essential elements of the GKI are the pondage and the weir, the headrace tunnel and the powerhouse (Fig. 1).

The weir facility is being constructed in the border area between Martina and Nauders with a weir 15 m high to retain water. From here, up to 75 m3/s of water will be conducted down the 23.2 km headrace tunnel and the penstock to the powerhouse in Prutz/Ried, where two powerful machine sets, each consisting of a Francis turbine and a generator with a power of 89 MW, will generate environmentally friendly electricity. The water then flows through an underground channel back into the Inn. The total investment in the project is about 410 m. Euro.

The main works for the Gemeinschaftskraftwerk Inn are divided into several construction contracts. Hochtief Solutions have been awarded the construction of the headrace tunnel, which is more than 23 km long. The contract is the largest of the altogether three contracts for the power station on the River Inn. The headrace tunnel has a diameter of 6.5 m and runs underground down the orographically right-hand side of the valley from the pondage in Ovella to the powerhouse in Prutz, at depths below ground level of between 130 and 1,200 m according to location. The starting point for the construction of the tunnel is the adit in Maria Stein, from where the actual headrace tunnel will be bored by a TBM about 12.7 km towards the weir and 8.9 km towards the powerhouse. At the weir in Ovella and at the powerhouse in Prutz/Ried, tunnels will also be driven in the opposing direction.

The tunnel will be lined with segments, which will be produced in a field production plant on site. The contract value is 132 m. Euro and the tunnel should be completed by the middle of 2018.

The contract for the penstock and the powerhouse in Prutz/Ried will be undertaken by a joint venture of the companies Bemo Tunnelling GmbH, G. Hinteregger & Söhne Baugesellschaft

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Fig. 1. Overview of the project area (photo: GKI) Bild 1. Übersicht Projektgebiet (Foto: GKI)

m.b.H., Östu-Stettin Hoch- und Tiefbau GmbH and Wayss & Freytag Ingenieurbau AG. The works include a closed underground channel (length 310 m), the powerhouse (34 m × 23 m × 34.8 m) for two vertical machine sets, the penstock (inclined shaft, internal diameter 3.8 m, length 380 m with a slope of 31 %, 40 m horizontal section) to be excavated by drill and blast with steel armouring backfilled with concrete, the surge tank (shaft with internal diameter 13.8 m, height 100 m, with membrane and insitu concrete inner lining; upper chamber: length 70 m, cross-section 35 m²), the apparatus chamber (at the crossing of the surge tank/penstock/ tunnel driven from the other direction) with access tunnel (length 320 m), the drill and blast tunnel from the opposing direction in the pressure tunnel (excavated diameter 6.5 m, length 1.000 m with in-situ concrete lining) and all auxiliary works such as electricity transmission, access roads and traffic diversion. The contract volume is about 56.4 m. Euro.

In addition to the boring of the headrace tunnel, the adit, access tunnel (Fig. 2) and starting cut will all be excavated conventionally by drill and blast.

The northernmost part of the pressure tunnel will also be excavated cyclically in full-face with two-pass lining. The support layer will consist of reinforced

shotcrete with rock bolts and steel arches, and the inner lining will be an in-situ concrete ring provided with waterproofing membrane in places. For the conventional driving of the various tunnels and access tunnel and the construction of the inclined shaft, DSI Österreich delivered the complete palette of support materials needed (Fig. 3). These are essentially: – Omega-Bolt expanding friction bolts, 120 kN, in individual lengths of 3 and 4 m with top heading anchor plates and sleeve pipes, – SN anchors, SN25-250, L = 4 and 6 m with Alwagrip special ribbing incl. top heading anchor plates 200/200/ 10 mm, nuts and washers, – Dywi Drill hollow bar system, ∅ R32250 and R32-280, L = 2, 3 and 4 m, – Steel spiles of grade BST 550, ∅ 25 mm, – Self-drilling spiles, R32, L = 3 and 4 m incl. hardened drill bit and – Pantex lattice girders, type 130/20/30 and tape 70/20/30 with welded nut pairs and spacers.

Further information DYWIDAG-Systems International GmbH Alfred-Wagner-Strasse 1 4061 Pasching/Linz, Austria www.dywidag-systems.at

Product Information DSI liefert Stützmittel für das Gemeinschaftskraftwerk Inn Mit dem Gemeinschaftskraftwerk Inn (GKI) – ein gemeinsames Projekt der Tiroler Wasserkraft AG, der Engadiner Kraftwerke AG sowie der Verbund AG – entsteht am Oberen Inn im schweizerisch-österreichischen Grenzgebiet zwischen der Schweizer Gemeinde Valsot und der österreichischen Gemeinde Prutz ein neues großes Laufwasserkraftwerk. Das in Österreich und der Schweiz umfassend geprüfte Kraftwerk erzeugt im Anschluss an die rund vierjährige Bauphase (2014 bis 2018) jährlich über 400 GWh Strom aus Wasserkraft.

Die wesentlichen Elemente des GKIs sind der Stauraum und die Wehranlage, der Triebwasserstollen sowie das Krafthaus (Bild 1). Im Grenzgebiet zwischen Martina und Nauders entsteht die Wehranlage mit einem 15 m hohen Wehr zur Wasserfassung. Von dort werden bis zu

Fig. 2. Access tunnel (photo: DSI) Bild 2. Zugangsstollen (Foto: DSI)

75 m3/s Wasser über den 23,2 km langen Triebwasserstollen und dem Druckschacht zu den Turbinen im Krafthaus in Prutz/Ried geleitet, wo zwei leistungsstarke Maschinensätze, bestehend aus je einer Francis-Turbine und einem Generator mit einer Leistung vom 89 MW, umweltfreundlichen Strom erzeugen. Das Wasser fließt durch einen unterirdischen Kanal wieder in den Inn zurück. Die Gesamtinvestitionen in das Projekt betragen ca. 410 Mio. Euro.

Die Hauptbauarbeiten für das Gemeinschaftskraftwerk Inn sind in mehrere Baulose aufgeteilt. Hochtief Solutions erhielt den Zuschlag für den Bau des mehr als 23 km langen Triebwasserwegs.

Das Baulos ist das größte der insgesamt drei Baulose des Wasserkraftwerks am Inn. Der Triebwasserstollen mit einem Ausbruchdurchmesser von 6,5 m verläuft auf der orografisch rechten Talseite unterirdisch vom Stauraum in Ovella zum Krafthaus in Prutz, je nach Lage zwischen 130 und 1.200 m tief unter der Oberfläche. Der Ausgangspunkt für den Stollenbau ist der Fensterstollen in Maria Stein. Von dort aus wird der eigentliche Triebwasserstollen ca. 12,7 km in Richtung Wehranlage und ca. 8,9 km in Richtung Krafthaus mithilfe von TVM gefräst.

Bei der Wehranlage in Ovella und beim Krafthaus Prutz/Ried erfolgt ein Gegenvortrieb. Der Ausbau des Tunnels erfolgt mit Tübbingen. Diese Stahlbetonteile werden vor Ort in einer Feldfabrik hergestellt. Der Auftragswert liegt bei 132 Mio. Euro. Der Stollen soll bis Mitte 2018 fertiggestellt werden.

Das Baulos Kraftabstieg und Krafthaus Prutz/Ried wird eine Arbeitsgemeinschaft aus den Unternehmen Bemo Tunnelling GmbH, G. Hinteregger & Söhne Baugesellschaft m.b.H., Östu-Stettin Hoch- und Tiefbau GmbH und Wayss

Fig. 3. In addition to various bolts and spiles, DSI also supplied the Pantex lattice girders (photo: DSI) Bild 3. Neben verschiedenen Ankern und Spießen liefert DSI auch die Pantex-Gitterträger (Foto: DSI)

& Freytag Ingenieurbau AG ausführen.

Die Arbeiten umfassen den geschlossenen Unterwasserkanal (Länge 310 m), das Krafthaus (34 m × 23 m × 34,8 m) für zwei vertikale Maschinensätze, den Kraftabstieg (Schrägschacht, Innendurchmesser 3,8 m, Länge 380 m mit 31 % Neigung, 40 m Flachstrecke) im konventionellen Vortrieb mit hinterbetonierter Stahlpanzerung, das Wasserschloss (Schacht: Innendurchmesser 13,8 m, Höhe 100 m, mit Folie und Ortbetoninnenschale, Oberkammer: Länge 70 m, Querschnitt 35 m²), die Apparatekammer (im Kreuzungsbereich Wasserschloss/ Kraftabstieg/Gegenvortrieb Druckstollen) mit Zugangstunnel (Länge 320 m), den konventionellen Gegenvortrieb im Druckstollen (Ausbruchsdurchmesser 6,5 m, Länge 1.000 m mit Ortbetonauskleidung) sowie sämtliche Nebenarbeiten wie Energieableitung, Zufahrten und Verkehrsumlegungen. Der Auftragswert beträgt rund 56,4 Mio. Euro.

Neben dem maschinell aufzufahrenden Triebwasserstollen entstehen die Fensterstollen, Zugangstunnel (Bild 2) und Anfahrbereiche zyklisch im Sprengvortrieb. Der nördlichste Teil des Druckstollens wird ebenfalls im zyklischen Vortrieb im Vollausbruch vorgetrieben und zweischalig ausgebaut. Dabei besteht die Außenschale aus einer bewehrten Spritzbetonschale mit Felsankern und Stahlbögen. Bei der Innenschale handelt es sich um einen Ortbetonring, der stellenweise mit einer Dichtbahn versehen wird.

Für die konventionellen Vortriebe der verschiedenen Tunnel und Zufahrtsstollen sowie den Bau des Schrägschachts lieferte DSI Österreich die komplette Palette an benötigten Stützmitteln (Bild 3).

Diese umfasste im Wesentlichen: – Omega-Bolt Reibrohrexpansionsanker, 120 kN, in Einzellängen von 3 und 4 m mit Kalottenankerplatten und Überschubrohren, – SN-Anker, SN25-250, L = 4 und 6 m mit Alwagrip Sonderrippung inkl.

Kalottenankerplatten 200/200/ 10 mm, Muttern und Beilagscheiben, – Dywi Drill Hohlstab-System, ∅ R32250 und R32-280, L = 2, 3 und 4 m, – Stahlspieße aus BST 550, ∅ 25 mm, – Selbstbohrspieße, R32, L = 3 und 4 m inkl. gehärteter Bohrkronen sowie – Pantex Gitterträger, Typ 130/20/30 und Typ 70/20/30 mit angeschweißten Mutterpaaren und Abstandhaltern.

Weitere Informationen DYWIDAG-Systems International GmbH Alfred-Wagner-Strasse 1 4061 Pasching/Linz, Austria www.dywidag-systems.at

Geomechanics and Tunnelling 9 (2016), No. 1

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Site Report Minax ensures safety in a deep tunnel The Chilean state mining concern Codelco has ordered from Geobrugg the supply of dynamic mesh for the stabilisation of galleries in the “El Teniente” copper mine. The mine has been extracting copper ore since 1904 from the largest known copper deposit in the world, with an annual production is more than 400,000 t of fine copper.

Since the original development of the mine, more than 3,000 km of galleries have been driven.

The high-strength and dynamic steel mesh from Geobrugg, which is marketed under the name Minax, serves as support mesh for galleries and to provide protection against rockfall and caving from the tunnel sides (Fig. 1). For Codelco, two factors were decisive: – the dynamic stabilisation with highstrength steel wire mesh, – the possibility of safely, quickly and automatically installing the mesh.

Fig. 1. The dynamic mesh supports mine galleries against caving (photo: Geobrugg) Bild 1. Das dynamische Geflecht schützt im Bergwerksstollen vor Ausbrüchen (Foto: Geobrugg)

Since Minax is made of corrosion-resistant and high-strength steel wire, it is the only mesh that is suitable for tunnel stabilisation in the geologically very challenging conditions in deep mine galleries. The fully automatic mounting of the safety mesh also enables rapid installation and the highest safety for the miners, since they can stay out of the danger area during the entire installation process (Fig. 2).

A global network of branch offices and production locations all over the world also enables the Geobrugg Group to supply Minax mesh in various wire thicknesses, even in large quantities and quickly. All mesh variants possess an extremely high strength of 1,770 N/mm2.

In order to ensure the long lifetime of the mesh, Geobrugg analyses the geological conditions in advance and provides

the Minax mesh with the appropriate corrosion protection.

Further information: Geobrugg AG Aachstrasse 11 CH-8590 Romanshorn Switzerland www.geobrugg.com

Minax sorgt für Sicherheit in tiefe Stollen Der staatliche chilenische Bergbaukonzern Codelco beauftragte Geobrugg mit der Lieferung von dynamischem Geflecht zur Stabilisierung der Stollen im Kupferbergwerk „El Teniente“. Das Bergwerk baut seit 1904 Kupfererz in der weltweit größten bekannten Kupferlagerstätte ab.

Die Jahresproduktion liegt bei mehr als 400.000 t Feinkupfer. Seit der Eröffnung des Bergwerks sind mehr als 3.000 km Strecken aufgefahren worden.

Das hochfeste und dynamische Stahldrahtgeflecht von Geobrugg, das unter der Markenbezeichnung Minax vertrieben wird, dient als Verzugsnetz für Strecken und soll vor Steinfall und Ausbrüchen aus der Tunnellaibung schützen (Bild 1). Für Codelco waren zwei Faktoren ausschlaggebend: – Die dynamische Stabilisierung durch hochfestes Stahldrahtgeflecht, – Die Möglichkeit, das Geflecht sicher, schnell und automatisiert installieren zu können.

Da Minax aus korrosionsresistentem und hochfestem Stahldraht gefertigt ist,

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Geomechanics and Tunnelling 9 (2016), No. 1

Fig. 2. Safe and rapid installation of the mesh through mechanical mounting (photo: Geobrugg) Bild 2. Sichere und schnelle Installation der Geflechte durch maschinelles Montieren (Foto: Geobrugg)

Site Report/Diary of Events ist dieses das einzige Geflecht, das für die Tunnelstabilisierung bei den geologisch sehr anspruchsvollen Bedingungen in tiefen Bergewerksstollen geeignet ist.

Darüber hinaus ermöglicht die vollständig automatisierte Montage des Sicherheitsgeflechts sowohl eine schnelle Installation als auch höchste Sicherheit für die Bergleute, da diese sich während des gesamten Installationsprozesses nie im Gefahrenbereich aufhalten (Bild 2).

Ein globales Netzwerk mit Niederlassungen und Produktionsstätten auf der ganzen Welt ermöglicht es der Geobrugg Gruppe, das Minax-Geflecht in unterschiedlichen Drahtstärken auch in großen Mengen und kurzfristig zu liefern.

Alle Geflechtsvarianten zeichnen sich durch ihre extreme Festigkeit von 1.770 N/mm2 aus. Um eine lange Lebensdauer der Geflechte gewährleisten zu können, analysiert Geobrugg vorab

die geologischen Bedingungen im jeweiligen Bergwerk und stattet das MinaxGeflecht dementsprechend mit dem benötigten Korrosionsschutz aus.

World Tunnel Congress 2016

• Other underground structures and disposal of radioactive waste • Geotechnical investigation and monitoring • Numerical modelling, development and research • Equipment, operational safety and maintenance in underground structures • Risk management, contractual relationships and funding • Historical underground structures and tunnel reconstruction

Weitere Informationen: Geobrugg AG Aachstrasse 11 CH-8590 Romanshorn Schweiz www.geobrugg.com

Diary of Events 4th European Forum of Road Tunnel Safety Officers 9 to 10 March 2016, Rotterdam, The Netherlands Topics • Operating tunnels safety during refurbishment • Commissioning and testing of new and refurbished tunnels www.ita-cosuf.org

23th Conference on Geotechnics 10 March 2016, Darmstadt, Germany Topics • Geotechnics and natural hazards • BIM in geotechnics • National and international projects • Intercity building/tunnelling • Legal questions and standardization www.geotechnik.tu-darmstadt.de

31. Christian Veder Colloquium 31 March and 1 April 2016, Graz, Austria

22 to 28 April 2016, San Francisco, California, USA Topics • Case histories • Contracting practices • Design/analysis • Engineering for resiliency • Environmental challenges/ sustainability • Hard rock tunnelling • High stress tunnelling • Human resources challenges • Instrumentation and Monitoring • Large bore TBM projects • Underground caverns • New technologies • Operations and maintenance • Planning and financing for underground projects • Risk management • Safety in design and construction • Sequential excavation methods • Seismic design and performance • Site investigations/geotechnical • Soft ground tunnelling • Unchartered territories/conditions • Urban planning and development • Challenging future projects

Topics • Ground improvement • Design, tender, contract, execution

www.wtc2016.us

www.cvk.tugraz.at

Ground Improvement in Underground construction and mining

bauma 2016 11 to 17 April 2016, Munich, Germany www.bauma.de

2. Felsmechanik-Tag 13. April 2016, Weinheim, Deutschland Thema • Felsmechanische Fragestellungen beim Bahnprojekt Stuttgart-Ulm www.felsmechanik.eu

www.ucprague.com

Road to Tunnel Expo 26 to 28 May 2016, Ankara, Turkey www.road2tunnel.com/en/

5th Munich Tunnelling Symposium 3 June 2016, Neubiberg, Germany Topics: • Design methods, BIM • Tunnels in Bavaria • Large scale projects • Sustainability in tunnelling www.tbsm.de

9 to 11 May 2016,Boulder, Colorado, USA

37th Grouting Fundamentals & Current Practice Short Course June 13–17, 2016, Austin, Texas (USA)

groundimprovementshortcourse.com

13th International Conference Underground Construction 23 to 25 May 2016, Prague, Czech Republic Topics • Urban transport tunnels – design and construction • Non-urban transport tunnels – design and construction

Topics • Procedures for cement and chemical grouting • Grouting of rock under dams • Groundwater cutoffs and composite seepage barriers • Grouting of rock anchors and micropiles • Jet grouting, compensation grouting, permeation grouting, compaction grouting • Grouting for underground structures

Geomechanics and Tunnelling 9 (2016), No. 1

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Diary of Events • Overburden and rock drilling methods • Instrumentation and monitoring www.groutingfundamentals.com

Swiss Tunnel Congress 2016 15 to 17 June 2016, Luzern, Switzerland Topics • Challenging international tunnelling projects • Challenging tunneling projects in Switzerland www.swisstunnel.ch

50th US Rock Mechanics/ Geomechanics Symposium 26 to 29 June 2016, Houston, Texas, USA Topics • Geomechanics for civil engineering • Geomechanics for petroleum engineering • Geomechanics/rock mechanics for mining engineering • Geomechancis and environmental risk • Induced/triggered seismicity • Waste disposal-produced water, CO2 sequestration • Depletion-induced surface subsidence • Rock mass, fault zone, fractured rock, weak rock, rock fabric • Stability and support • Fracture mechanics • In situ stress, pore pressure measurements, predictions • Geomechanics and geothermal exploration and production • Coupled processes – geomechanics, fluid flow, heat, transport • Numerical/analytical/Constitutive modelling of rock and rock processes • Computational advances and data analytics • Geophysics and geology in geomechanics • Rock heterogeneity across all length scales www.amarocks.org

Eurock 2016 29 to 31 August 2016, Cappadocia, Turkey Topics • Design methodologies and analysis • Rock dynamics • Rock mechanics and rock engineering at historical sites and monuments

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Geomechanics and Tunnelling 9 (2016), No. 1

• Underground excavations in civil and mining engineering • Coupled processes in rock mass for underground storage and waste disposal • Rock mass characterization • Petroleum geomechanics • Instrumentation-monitoring in rock engineering and back analysis • Risk management • New frontiers http://eurock2016.org/

34. Baugrundtagung 2016 14 to 16 September 2016, Bielefeld, Germany Topics • Innovation • Spezialtiefbau • Erd- und Grundbau • Tunnelbau • Infrastrukturprojekte • Geotechnik für regenerative Energie und nachhaltiges Wirtschaften • Normung • Prognosen und Qualitätssicherung www.baugrundtagung.de

10th Austrian Tunnel Day 12 October 2016, Salzburg, Austria Topics .

• Special challenges at current large construction sites • BIM in tunnelling • Contractual project specifications in tunnelling – What are the misconceptions?

• Innovation award www.oegg.at

• Salzmechanik – Endlagerung – Verwahrung • Nationale und internationale Bauprojekte tu-freiberg.de/fakult3/gt/feme/

TBM in difficult grounds 16 to 18 November 2016, Istanbul, Turkey Topics • Case studies of TBMs in various difficult grounds and complex geology • Characterization of difficult grounds for TBM tunnelling • Laboratory testing and physical modelling of TBM excavation • Numerical modelling of TBM interaction with grounds • Ground treatment for TBMs in difficult grounds, • Application of foam and soil conditioning • Support design for TBM tunnels in variable and complex grounds • Monitoring and back analysis for TBM tunnels in difficult grounds • Development of hybrid TBMs for difficult and varying grounds • Probe drilling and umbrella arch ahead of TBM cutterhead • Use of TBMs in mines and for other special applications • TBM selection, performance assessment and operation management • Decision aids for tunnelling and risk management of TBM in difficult grounds www.tbmdigsturkey.org

Stabilitätsfragen in der Geotechnik 17. November 2016, Leoben, Österreich

65. Geomechanics Colloquium 13 to 14 October 2016, Salzburg, Austria Topics • Geothermal energy – experiences, chances and risks • TBM – expectations and reality • Geomechanical aspects in mining • Large projects in Austria www.oegg.at

45. Geomechanik-Kolloquium 11. November 2016, Freiberg, Germany Themen • Geothermie und Gebirgsmechanik • Gesteins- und gebirgsmechanisches Versuchswesen

Topics • Planung, Berechnung und Überwachung • Fokus auf Hang- und Böschungsstabilitäten Information: t.pirkner@voebu.at robert.galler@unileoben.ac.at

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Geomechanics and Tunnelling 9 (2016), No. 1

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Preview Rubriken

Geomechanics and Tunnelling 2/2016 Gotthard Base Tunnel Gotthard-Basistunnel Hans-Peter Vetsch, Peter Zbinden, Ernst Märki, Heinz Ehrbar Gotthard Base Tunnel – the selection of a tunnel system as seen today Gotthard-Basistunnel – Wahl des Tunnelsystems aus heutiger Sicht

Gregor Doppmann, Monika Burri, Raphael Wick The success story of environmental support of construction at ErstfeldAmsteg Erfolgsgeschichte Umweltbaubegleitung Erstfeld-Amsteg

Max John, Werner Dallapiazza, Frederico Matousek Gotthard Base Tunnel: Comparison of prognosis and actual conditions of engineering geology and tunnelling Gotthard-Basistunnel: Vergleich Prognose – Befund aus baugeologischer und tunnelbautechnischer Sicht

Alex Sala, Raphael Wick Gotthard Base Tunnel – Technical overview of the project Gotthard-Basistunnel – Technische Projektübersicht

Luzi R. Gruber, Uwe Holstein Conventional tunnel drive from Sedrun Konventionelle Vortriebe Sedrun

Bruno Röthlisberger, Daniel Spörri, Michael Rehbock Unexpectedly difficult ground conditions in the MFS Faido Unerwartet schwierige Baugrundverhältnisse in der MFS Faido

Arthur Hitz, Matthias Kruse “The mountain from the mountain” – handling the tunnel spoil material „Der Berg aus dem Berg“ – Bewirtschaftung des Tunnelausbruchmaterials

In deep tunnels with restricted opportunities for investigation, deviations from the prognosis naturally occur during the construction phase. These are caused by the different effects of geological and hydrogeological conditions on tunnelling. At the Gotthard Base Tunnel, it turned out that the rock mass showed more favourable behaviour than forecast at several zones, which had been categorised as critical. Nonetheless, challenging situations did arise due to geological effects, for example due to loosening of the rock mass in the backup area destroying the shotcrete support layer.

Bei einem tiefliegenden Tunnel mit beschränkten Möglichkeiten der Erkundung treten bei der Ausführung naturgemäß Abweichungen von der Prognose auf. Diese haben ihre Ursache in den geologischen und hydrogeologischen Verhältnissen, die sich unterschiedlich auf den Vortrieb auswirken. Beim Gotthard-Basistunnel hat sich gezeigt, dass sich in einzelnen als kritisch eingestuften Bereichen das Gebirge günstiger verhalten hat als prognostiziert. Dennoch kam es aufgrund von geologischen Einflüssen zu herausfordernden Situationen, z. B. als aufgrund von Gebirgsentfestigung im Nachläuferbereich die Spritzbetonschale zerstört wurde.

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