OnSite Underground September 2021

merlo.com

CONTENT Supplement issue on ONSITE CONSTRUCTION n. 6 – September 2021

4 News

by Editorial staff

COVER STORY

38 Robbins

20 Casagrande

OFTA process in China

New flagship in operation

in UK

by Ettore Zanatta

by Pietro Gabrielli

42 Sandvik

8 Forrestfield-Airport Link

Ready to take off in Perth

24 Bauer Spezialiefbau GmbH

The new BAUERdigital portal

New machines,

new capabilities

by Gianni Gennari

by Pietro Gabrielli

by Ettore Zanatta

46 Epiroc

Next generation in underground mining

DRILLING 12 Trevi Australia

The Forrestfield-Airport Link Project

by Ettore Zanatta

18 Soilmec

28 Comacchio

News from the CH Line

by Stefano Vitali

30 Liebherr

Digitalization in deep foundation work

EQUIPMENT

by Pietro Gabrielli

50 Tecniwell

The “Eagle” evolution!

by Ettore Zanatta

Electrical innovation

by Ettore Zanatta

by Stefano Vitali

CASING 54 SIP&T

To work safe and fast

TUNELLING

by Stefano Vitali

Editor in chief Ettore Zanatta - ettore.zanatta@capoversoeditrice.it

Frequency Extra Issue

Sales Manager Luisa Casazza - l.casazza@capoversoeditrice.it

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by Stefano Vitali

34 Sennebogen

Two duty cycle cranes for RTE

Contributors: Pietro Gabrielli, Gianni Gennari, Alessandro Negri, Emanuele Villa, Stefano Vitali

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C apoverso editrice

ESD in hydraulic filters

by Emanuele Villa e Alessandro Negri

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NEWS KLEMM

Universal drilling rig Klemm KR 606-3 The KR 606-3 drilling rig is the smallest and lightest universal drilling rig from KLEMM Bohrtechnik. It fulfills all the requirements for extreme compactness and highly variable kinematics. The KR 606-3 can be used to reach diverse and extreme drilling positions in especially confined conditions. Due to the modular drilling rig concept, a wide spectrum of drilling applications can be covered, including underpinning, jet grouting, micro-piling, soil nailing and anchoring.

The newly developed drill rig kinematics allow the boom to rotate around the vertical axis of the drill rig. Other important features include the telescopic function of the heightadjustable boom, and the tilt and rotation function of the mast carrier, which, among other things, enables drilling positions to be set up conveniently alongside the crawler tracks. Four outriggers support the drilling rig, which, along with the asymmetrically telescopic chassis, ensure a high degree of stability.

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With its compact dimensions, the rig is predestined for use within buildings and other construction works. Using the proven remote control unit with display, the operator is always able to assume a safe working position close to the drilling rig. In accordance with the requirements of EN 16228, operator safety is ensured by the high, functional safety of the control concept. A separating safety guard for moving parts during the work process is available.

The modular mast system includes the 140/3 type mast with gear feed and 30 kN retraction force, and the 120 type mast with cylinder feed and 24 kN retraction force in graduated frame lengths. The 140/3 type mast is also available in a sectional version. Even greater flexibility is achieved through the newly developed modular system of the PP 45E and PP 55G Power Packs. Like the drilling rig itself, both Power Packs are very narrow, allowing them to pass through confined spaces. The Power Packs are available either on wheeled chassis for towing, on rubbertracked crawlers, or without chassis as a stationary unit.

The Power Pack PP 45E is powered by a three-phase motor with 45 kW output, while the Power Pack PP 55G has a diesel engine with an

output of 55 kW. The diesel engine complies with emissions regulations EU stage V and a version complying with emissions regulations EU stage IIIB is also available. The hydraulic system features include a load sensing pump and CAN bus controlled control blocks with high precision controllability and reproducibility. Drilling operations using light hydraulic drifters can be carried out without incurring any problems.

Connecting hoses for the KR 6063 are available in the following lengths: 2 m to connect the KR 6063 with the Power Pack on a wheeled chassis when hitched, 5 m to connect the KR 606-3 with the Power Pack on crawlers, 25 m of standard length and 40 m of longest available connecting hose.

KLEMM newly developed universal drilling rig KR 606-3 is so predestined for extreme drilling positions in especially confined spaces. Due to the modular drilling rig concept, a wide spectrum of applications can be covered: underpinning, jet-grouting, micropiling, soil nailing and anchoring are all possible with what is currently the smallest and lightest KLEMM drilling rig available. The drilling rig, of course, comes with all safety components according to EN 16628 and the diesel engine complies with EU emission level V.

G LO B A L D R I L L I N G E X P E R T I S E

CUSTOMIZED STOP-END-ELEMENT VISIT US OUTDOOR AREA

AISLE H

BOOTH 28

www.sipdrill.it

NEWS BHH

Best performer in India GHH India, with its mining contracting company GHH BUMI Mining Service, has received the Best Performing Business Partner Award.

In a Covid pandemic driven online event, GHH India, with its mining contracting subsidiary, GHH Bumi Mining Service, was awarded Best Performing Business Partner by Vedanta Group/Hindustan Zinc Ltd (HZL) in the presence of Founder & Executive Chairman Mr. Anil Agarwal, Vedanta Resources Limited, Mr. Sunil Duggal, Vedanta Group CEO & Mr. Arun Misra, CEO, Hindustan Zinc Limited along with their other Executive team. The award winner was chosen out of all business partners and was given in recognition for a job well done.

Over the last 6 months, GHH Bumi has been doing contract mining at Zawar Mala mine, and has been presented the award based on excellent performance involving all mining contract activities like safety, production, asset

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ONSITEUNDERGROUND - september 2021

optimization.

GHH BUMI Mining Service was established late last year. Since January 2021, GHH BUMI has been responsible for production and mine development with more than 350 employees at the Zawar Mala mine. For this purpose, the company has access to more than 20 load haul dumpers (LHDs), dump trucks and drilling rigs from the GHH Group.

Dr. Jan Petzold, CEO of GHH Group was very pleased to receive the award from HZL. “With this award, we as GHH Group see ourselves confirmed in our efforts as a reliable business partner for HZL.

A cooperation that started almost 4 years ago with the supply of mining machinery and has resulted in being awarded as Mining Contractor and OEM. This is a special incentive to be able to conclude the second MDO contract with HZL, which is currently in preparation”. In the ceremony Dr. Petzold thanked his team involved, Henry Landman, GM of GHH Bumi and Rajeshwar Singh, MD of GHH India, for their hard work and efforts in achieving this award, which they will certainly look forward to celebrating with the team on the ground. The latest generation of GHH mining equipment, with its new dump truck MK-42, LHDs LF14 and LF-10 as well as two boom drill rigs FM 2.3 from GHH group company Mine Master are on its way to India and are expected to be on site beginning of August. GHH Bumi is also currently working on preparing for the expansion Mochia Balaria Decline Project, where a rapid development proposal is under way.

COVER STORY Forrestfield-Airport Link

READY TO TAKE OFF IN PERTH The new metro rail line that will allow residents in the eastern suburbs of Perth (Australia) to travel 20 minutes to the city centre.

The project includes 8.5 km of new tracks, 8 km of it in tunnels The tunnels vary in depth along the route, with the deepest point being beneath the Swan River, where the centre of the tunnel will be approximately 26 m below the riverbed

by Gianni Gennari

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T

he $1.86 billion ForrestfieldAirport Link is jointly funded by the Australian and Western Australian governments and will deliver a new rail service to the eastern suburbs of Perth – with three new stations at Redcliffe, Airport Central and High Wycombe.

The rail link forms part of the METRONET vision to create liveable communities connected by world class public transport. The line will spur off the existing Midland Line near Bayswater Station and run to High Wycombe through twin-bored tunnels.

Planning for Forrestfield-Airport Link began in 2008, with discussions around how the suburban rail network could best be connected to Perth’s growing eastern suburbs. The project was launched in August 2014 following approval from the State Government.

In April 2016 the Public Transport Authority awarded the design, construct and maintenance contract to Salini Impregilo (now Webuild) – NRW Joint Venture.

First trains will operate on the new Airport Line in the first half of 2022.

Construction of tunnels The Forrestfield-Airport Link will see a new rail line connect the railway east of Bayswater Junction to High Wycombe with 8.5 km of new tracks, 8 km of it in tunnels.The use of underground tunnels reduces the

september 2021 - ONSITEUNDERGROUND

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COVER STORY

7m The diameter of each tunnel

60,000 n° The number of pre-cast concrete segments

26 m The depth of the tunnels as they run under the Swan River

infrastructure, including bentonite and slurry treatment plants, which supported the tunnel boring machines. With tunnelling now complete, the infrastructure will be demobilised, making room for the construction of the multi-deck car park and further transit-orientated development.

The tunnel boring machines were launched from this site in 2017 and arrived at Bayswater Junction in 2020, constructing the tunnels along the way. The tunnels vary in depth along the route, with the deepest point being beneath the Swan River, where the centre of the tunnel will be approximately

26 m below the riverbed. Overall, the depth of the tunnels averages 20 m below the surface. Cross passages (allowing access between the tunnels) and emergency exits are being constructed at various points along the rail route.

There are various types of TBMs to cater for different ground conditions and project requirements. For this project, the two TBMs are Mixshield which use the latest dual-mode technology capable of adapting to variable ground conditions (such as sand, rock and clay) as the machine progresses.

The first TBM was named “Grace”, in honour of pre-primary student Grace

project’s impact on the environment and the community during both construction and operational phases.

It also avoids any interference with vital aviation infrastructure at Perth Airport.

The construction phase started late 2016 with site establishment at High Wycombe. A further three construction sites were established at Perth Airport, Redcliffe and Bayswater in 2017, as well as a number of smaller sites (mainly within road reserve) for cross passages and emergency exits.

The most significant construction site for the Forrestfield-Airport Link tunnels is near the tunnel portal at High Wycombe. This area houses the key McPhee who was nominated by her classmates at Edney Primary School in High Wycombe. The students said Grace, who is undergoing treatment for leukaemia, was the toughest person they knew - a toughness the TBM would need to bore through the earth. This TBM was decorated with artwork by Year 6 Walliston Primary School student Georgia Fields.

The second TBM was named “Sandy” as suggested by High Wycombe Primary School Year 4 student Sarah Spratt. Sarah was inspired after finding a sandgroper in her backyard, as the local insect (which 10 ONSITEUNDERGROUND - september 2021

ITALIAN ABSTRACT

PRONTI AL DECOLLO A PERTH Una nuova linea ferroviaria metropolitana che consentirà ai residenti della periferia est di Perth (Australia) di raggiungere il centro città in 20 minuti. Il progetto prevede 8,5 km di nuovi binari, di cui 8 km in galleria I tunnel variano in profondità lungo il percorso, con il punto più profondo sotto il fiume Swan, dove il centro del tunnel sarà a circa 26 m sotto il letto del fiume.

is also a colloquial name for Western Australians) is ‘excellent at tunnelling, just like the TBM’. This TBM was decorated with artwork by Rossmoyne Primary School Year 5 students Faith Brand and Jood Al Jashammi.

Key components for TBMs were manufactured in various places around the world before an in-depth ninemonth assembly and testing program was conducted in China. Once testing was finished, they were disassembled and shipped to Henderson Port. The TBMs were then transported to site, reassembled and lowered into the dive structure at High Wycombe, where they tunnelled between High Wycombe and Bayswater.

During their 8 km journeys the TBMs excavated under Perth Airport and the Swan River, reaching up to 26 m depth below the surface.

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september 2021 - ONSITEUNDERGROUND

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DRILLING Trevi Australia

The ForrestfieldAirport Link Project The Forrestfield-Airport Link in Perth is a A$1.9B project that will deliver an 8.5 km extension of the existing urban rail network connecting the Midland Line, just past Bayswater Station, to Forrestfield High Wycombe, running underground in twin bored tunnels underneath the Swan River, Tonkin Highway and Perth Airport

by Ettore Zanatta

12 ONSITEUNDERGROUND - september 2021

T

his project, in Perth, comprises the design, construction and maintenance for 10 years of the Forrestfield-Airport Link, which will connect the growing eastern suburbs of the Australian city with the existing suburban rail network as well as the airport. In April 2016 the Public Transport Authority awarded the design, construct and maintenance

The Forrestfield-Airport Link will connect the growing eastern suburbs of Perth with the existing suburban rail network as well as the airport

contract to Salini-Impregilo (now WeBuild) - NRW Joint Venture. In the first year of operations the Airport Line is expected to generate 20,000 passengers trips on the network every day, as well as reduce road traffic and travel times.

The Project The project consists in: 7.14 km of twin underground rail tunnels, with an external diameter of approximately 7 m (the tunnel separation, measured from the centre of one tunnel to the centre of the other tunnel, varies between 13 m a nd 15 m with a maximum depth Ground Level-Rail Level of about 32m); three new railway stations; two dive structures, at Bayswater and Forrestfield High Wycombe; twelve Cross Passages; three Emergency Egress Shafts.

Jet-Grouting The Jet Grouting soil improvement technique was an allotted work for Trevi Australia. The scope of work includes the installation of jet grouted columns to create a consolidated block in correspondence with the cross passages, having both structural and hydraulic purposes, in order to allow the safe excavation of the connecting tunnels.

All JG columns were set in place prior to the passage of the TBM using both double fluid system, where the grout jet is assisted by an air shroud, and single fluid system, where only high-pressure grout is used.

Thediametersachievedwere2.2mand1.0m respectively. The jetting-drill string wa s composed of specially designed rods with two concentric coaxial, the inner for high-pressure grout and the outer for compressed air.

Pre-washing (or pre-cutting) technique, in which water is used to pre-erode the soil, was performed either during the drilling phase or in a separate phase prior to jetting. Maximum installation depth was up to 32 m using a triangular grid spacing from 1.35 m to 1.75 m, according with the column diameters and depths of the treatment. Prior to execution of the JG works three Field Tests were carried out in order to: test the effectiveness of the JG Parameters and methodology; set the operating modalities; acquire data to optimize the work methodologies. To produce the most reliable data, the trials were carried out according to the project technical specifications in areas and at depths where the geology reflects as much a s possible the characteristics of the soil to be treated. The trials were carried out with different sets of JG parameters and subsequent post installation tests including Coring, UCS and Modulus lab tests, Sonic Logging Testing and Permeability tests.

There were six Cross Passages (CP) and two Emergency Egress Shafts (EES) where Jet Grout treatment was required.

Dundas was the first location of the JG production works. september 2021 - ONSITEUNDERGROUND 13

DRILLING

columns; the data was plotted in 3D as built drawings, in order to evaluate the need for integrative columns to close any potential gaps.

The main equipment used for the site activities are drilling Rig (Soilmec SM-20), high Pressure Pump (Soilmec 7T-600J), batching Plant and drilling and Jetting Control System

The JG treatment within the Bassendean Sand from approximately 7 to 18 meters deep was quite superficial.

The particularity of the treatment was the geometry with the installation of inclined columns of up to 36 degrees from vertical and the use of the monofluid system for the columns with a greater inclination. These solutions were implemented due to the presence of a gas pipe line and Fiber Optic Cabling in close proximity to the treatment area. During execution of JG works a dedicated monitoring system was in place to ensure a safe working-condition and to avoid any damage to these utilities. As in CP10 Manheim, CP06 Car Park C and also in CP05 Brearley AV a top layer of very fine sand was encountered which influenced the treatment by the impossibility to use the Pre-Washing technique due to the risk of forming sink holes on the surface. To reduce the risk of collapsing and overturning of the rig two actions were adopted: removal of the Pre-Washing phase, to reduce the siphoning effect; a PreTreatment phase with mono-fluid columns, this to consolidate the upper portion of the ground assuring the stability of the working platform.

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Equipment for Jet Grouting works The main equipment used for the site activities are drilling Rig (Soilmec SM20), high Pressure Pump (Soilmec 7T-600J), batching Plant and drilling and Jetting Control System.

The boreholes were drilled using a rotary drilling methodology with drag/ tricone bit using water as a circulating fluid to remove the cuttings. To prevent the borehole from collapsing casing was used (in some locations the casing was up to 9 meters long) and also a diverter to facilitate the spoil removal from the site. The Jet Grouting parameter used in the project required a flow of 450 l/min with a pressure of 420 bar.

The air pressure range was between 9 to 12 bar. The capacity of the grout plant was up to 30 m³/hr and was connected to two cement silos with a capacity of 50 Ton each. To assure the necessary continuous flow of grout to the pump, an agitator with the capacity of 5 m³ was used also. Both the operational phases (drilling and jetting) were monitored by recording the principal parameters such as drilling speed and torque, rotation per minute (RPM), grout and air pressure and lifting speed. Verticality control was performed on 100% of installed

Artificial Ground Freezing The Artificial Ground Freezing soil improvement technique was an allotted work for Trevi Australia. The scope of work includes the application of a soilimprovement technique, having both structural and hydraulic purposes, to create a consolidated block in correspondence with the cross passages in order to allow the safe excavation of the connecting tunnels. The technique consists of freezing the water inside a volume of soil, according to a known geometry, by subtracting heat from the ground through special heat exchangers.

The frozen soil, where soil grains represent the aggregates and the binder is the frozen water, is 100% water-tight, whereas other consolidation methods can only reduce the natural permeability of the soil (i.e. jet Grouting). Treated soil is also homogeneous, with no weak points or planes and a high mechanical resistance is achieved, according to soil type and temperature. Last but not the least the technique of freezing is environmental-friendly as no products are injected into the ground, the refrigerant fluids never come directly in contact with the ground or with the ground water.

In the first stage just three cross passages (CP07, CP08 and CP09) were to be excavated under AGF due to the inapplicability of consolidation by means of Jet Grouting from the surface: The CP were all located below main runway of Perth airport with no possibility to work from the surface with heavy long mast equipment during landing and taking-off. In the second phase the client

gained confidence after the successful application in the first three CP, decided to consolidate through AGF also CP10 due to unexpected soil condition.

Drilling Activities and Equipment The Soilmec SM-5 and Drill mast Ripamonti EX300DTH set on an excavator were used to drill both freezing and control pipes.

Every single set up of the drilling equipment was previously checked by CAD due to the tunnels small diameter and due to the presence of slurry pipelines and ventilation system of the TBM in operation. To efficiently and precisely set the drilling position a special aligner was adopted, all pipes were finally set in place with an average deviation from the design less than 1%.

To monitor the actual position and

deviation of the installed pipes a special cylindrical device equipped with a LED was fabricated and placed within the borehole casing. A theodolite was installed on a fixed support at the tunnel end to site down the casing. All measured deviations were then used to build a 3D drawing which could be checked anytime to measure the actual

distance between every thermocouple and the closest freezing pipe.

Freezing Phase and Equipment The Brine method was the deployed on the FAL project with brand new 100 kW chillers installed within the tunnel close to each CP to be excavated.

The implemented dedicated monitoring system allowed the analysis of ice wall formation

september 2021 - ONSITEUNDERGROUND 15

DRILLING

The following main topics have been developed and monitored to achive the sustainability program: choice of equipment and utilization, efficiency of plant and equipment, careful utilization of natural resources, recycling, continuous control/inspection of performance, monitor energy use and water usage

The Chillers were all installed within tunnel 1 only, using two horizontal service holes at each CP to bring brine back and forth to Tunnel 2 also. These Chiller were specially designed for this tunnel diameter by having a maximum width of 1.80 m, allowing the clients plant and equipment to pass through either tunnel at any time. The water line connecting the chillers to the cooling towers (located at ground level at the closest available shaft) was more than 1.5 km long. Design goals,

in terms of both thickness between two isotherms at -2°C and average temperature within the frozen volume, have been achieved in 40-45 days for all treated CPs. Monitoring and Safety The implemented dedicated monitoring system allowed the analysis of ice wall formation. Due to this monitoring system it was possible to analysis, design and realize interventions during all phases

ITALIAN ABSTRACT

IL PROGETTO “FORRESTFIELD-AIRPORT LINK” L’opera - in cui si sta distinguendo Trevi Australia e che ha utilizzato, tra le molte altre attrezzature, anche due perforatrici Soilmec (una SM-20 e una SM-5) - prevede la progettazione, realizzazione e manutenzione per un periodo di 10 anni del Forrestfield-Airport Link, linea ferroviaria sotterranea che collegherà l’area orientale di Perth alla ferrovia suburbana esistente e all’aeroporto. Entro la fine del 2021 il progetto assicurerà una capacità di 20.000 passeggeri al giorno, riducendo contemporaneamente il traffico su gomma e i tempi di percorrenza.

Webuild e NRW, partner del Consorzio, realizzeranno tre stazioni, due tunnel da 8 km (per i quali sono state appositamente progettate due TBM), tre uscite di emergenza e parcheggi.

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(including the excavation phase) in areas where an increase of cooling power was necessary to avoid the formation of possible defects.

All data was shared within a daily report as well as on a dedicated “web monitoring system” implemented to give all key personnel the opportunity to check on any smart-device the soil temperature development at any time.

A surface laser survey system was also implemented in order to monitor the heave at ground level where planes were continuously landing and taking off. Recorded heave was within a range of 3 mm and 8 mm significantly less than the 15mm which was the max allowable heave. Around the site there was a very good and positive attitude towards safety, during inspections positive feedback was recorded. Safety procedures were implemented during the project to maintain a safe working area with focus on each individual’s safety performance and the overall safety on site: daily pre-start with discussion of the site activities and hazard reports; monthly training for all the crew; site inspections.

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DRILLING Soilmec

The “Eagle” evolution!

After the first performance on site of the SR-35 EVO last year, Soilmec offer of hydraulic drilling rigs has grown with the launch of the new “entry-level” model: the SR-30 Eagle

by Ettore Zanatta

S

oilmec rigs made history in the world of smallsized drilling rigs, by inaugurating a new era with the R-312 back in 1995, when it made its debut with a winning formula that offered a generous Diesel engine combined with a powerful rotary head. The rotary featured a fast spin-off speed and an immediately recognizable design, both compact and agile, making the rig suitable for use in a wide range of small applications.

After the first performance on site of

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the SR-35 EVO last year, the Soilmec offer of hydraulic drilling rigs has grown with the launch of the new “entry-level” model: the SR-30 Eagle.

With an operating weight of 31,3 tons (69004 lb) with a 4x9 kelly bar, the SR-30 Eagle can be easily transported to other jobsites without having to disassemble the excavation equipment, thus allowing a very fast setup in the next location.

A heavy-duty undercarriage and a counterweight of 3250 kg (7165 lb) allow the SR-30 Eagle to feature an agile turret with a tail swing radius of 3335 mm

(131.3 in) and to use at the same time the latest generation Soilmec Segmental Mast, designed to easily switch to the LHR and CFA configurations, hence offering great construction compactness and excellent torsional strength.

This solution enables an outstanding technological performance. In its LDP configuration, it is possible to install up to 5x9 self-mounting Kelly bar or not self-mounting 10.5-m-long bars (34.5 ft) with five elements at an excavation depth of 47.5m (155.8 ft). The LHR configuration has a minimum height of

The renovation of the latter includes customizations and many excavation automatisms to simplify and optimize the management of the excavation phase by the operator

7.4 m (24.3 ft) and can move 5x4 kelly bars, while the CFA configuration offers a mast extension for a maximum drilling depth of 22 m (72.2 ft).

The strength of the mast has made it possible to install a rotary with a maximum torque of 131 kNm (96619 lbft), capable of optimizing torque and rotation speed during excavation thanks to the automatic control of motor displacement. The rotary is provided with a new hydraulic block that has been redesigned for more efficient hydraulic performance to reduce consumption. To better support the rotary performance, the turret has been equipped with the latest generation StageV/Tier4f Diesel engine equipped with low-idle to improve fuel efficiency and decrease noise pollution. The 4.5-liter fourcylinders Cummins engine can deliver a maximum power of 149 kW (200 HP).

The hydraulic system, rationalized and pre-assembled on skid, together with the electrical circuit allow taking full advantage of the space available and facilitating both maintenance and troubleshooting operations.

The SR-30 Eagle is a truly modern, safe and technological rig thanks to a lot of standard equipment, such as the camera system with monitor in the cabin, the radio control for loading/ unloading operations and the new DMS ON BOARD. The renovation of the latter includes customizations

and many excavation automatisms to simplify and optimize the management of the excavation phase by the operator.

Among these, it is worth mentioning the automatic return to the centre hole, the anti-slack rope system and the load cell on the main winch for the kelly bar version as well as the automatic auger lifting and the autorotary and auto-drilling functions for the CFA configuration, which are all available upon request. The rig also comes with small but useful solutions, such as the high-pressure washer kit,

The SR-30 Eagle is a truly modern, safe and technological rig thanks to a lot of standard equipment, such as the camera system with monitor in the cabin, the radio control for loading/unloading operations and the new DMS ON BOARD

the compressor kit and the tool shelf, aimed at making daily work on site easier.

The new SR-30 Eagle embodies performance, technology and attention to details, making it a benchmark rig for the market of small-diameter drilling works. It is perfect to carry out works in residential areas and confined spaces and it is always ready to be moved to the next job site in a very short time.

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ITALIAN ABSTRACT

LA NUOVA PERFORATRICE SOILMEC SR-30 EAGLE Dopo il debutto in cantiere lo scorso anno della SR-35 EVO la gamma di perforatrici idrauliche di Soilmec si arricchisce con il nuovo modello SR-30 Eagle. Con un peso operativo di 27 t completa di asta kelly 4x9, questa nuova perforatrice può essere facilmente trasportata in un altro cantiere senza dover smontare le attrezzature di scavo, consentendo una rapida messa in opera nel sito successivo. Un robusto sottocarro e la zavorra da 3.250 kg le consentono di avere una torretta agile, con un raggio di coda di 3.335 mm, e di utilizzare il Segmental Mast di ultima generazione Soilmec, pensato per passare alle versioni LHR e CFA in modo semplice, con grande compattezza costruttiva e un’elevata resistenza alla torsione. Nella versione LDP è possibile installare aste di lunghezza 10,5 m con cinque elementi, per una profondità di scavo di 48 m. La versione LHR ha un ingombro minimo in altezza di 7,4 m e permette di movimentare aste kelly 5x4. Per la versione CFA è disponibile un’estensione antenna per una profondità massima di perforazione di 22 m.

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DRILLING Casagrande

New flagship in operation in UK The B470XP-2 is the new multifunction hydraulic piling rig designed to drill Bored Piles diameter 3500 mm max. up to 110 m drilling depth or up to 40 m CFA drilling depth and 1500 mm diameter

by Ettore Zanatta

T

he B470XP-2 is the new multifunction rig designed

by It a l i a n c o mp a ny Casagrande (Fontanafredda – Pordenone) to drill Bored Piles diameter 3500 mm max. up to 110 m drilling depth or up to 40 m CFA drilling depth and 1500 mm diameter. Extreme performances in cased CFA Double Head mode with 32 m CFA and to 24 m cased depth.

The latest techniques A powerful 450kW diesel engine complying with the latest EU Stage V emission regulations, drives all the working functions of the approx. 170 t rig. For higher power demanding operations, a 563kW engine is available as option. Due to the high torque of the rotary head of up to 470 kNm, the HD kelly bars and a powerful winch, the B470XP-2 can rapidly drill deep and large piles in hard soils. The crowd winch will drive casings deep into the ground with extreme accuracy having a line pull of 690 kN and rotary head stroke of 26 m. The HT front attachment mast 20 ONSITEUNDERGROUND - september 2021

support and the heavy-duty mast ensure strength of the structure for drilling deep and large piles in hard soils. Oversize tracks and modular counterweight give excellent stability and reduced ground pressure with reduced swing radius.

The rig is suitable for conversion in other piling modes as displacement piles, as well as diaphragm wall equipment with heavy duty hydraulic suspended grab for excavation to 80 m or Hydromill for more than 100 m excavation capability.

The new superstructure has been designed with hydraulic openings for quick and easy access during inspections and maintenance. Optional Stairs, platforms and railings provide excellent and safe accessibility to the engines, hydraulic and electronic systems and winches for inspection and maintenance.

The rig has been designed to make

assembly/disassembly and transport operations easy and safe thanks to the remote control and modular design of the machine. In double head mode, the two rotary heads are independent to increase the drilling depth capability and to allow better flow of drilled soil from auger. The lower rotary head with 420 kNm max torque and up 20 rpm rotation speed and the crowd winch 690 kN extraction/crowd force drive up to 1000 m diameter casing to 24 m depth. The H47 upper rotary head in DH mode can drill to 32,5 m CFA depth.

Added productivity The Smart Power Management (SPM) is an intelligent engine power management system that improves performances and productivity of the machinery. The SPM system monitors

the power flows drawn from the engine and allocates the maximum available power to the function required by the operator, ensuring the maximum power available. The cabin has been redesigned with improved ergonomics for comfort and soundproofing, both inside and out. The fan speed is related to the oil temperature in the smart oil heat exchangers, thus reducing fuel consumption and the overall noise level of the cooling system.

The new XP-2 series hydraulic and electronic systems can directly control the performance of the hydraulic pumps to achieve efficient, precise, and rapid execution of all operations.

The powerful diesel engine uses a highly efficient coupler to transmit the required power to the latest generation of hydraulic pumps, whilst ensuring The Casagrande B470 XP-2 is a multifunction machine designed to drill boreholes, to insert and extract casings, to power a casing oscillator, for piling by the continuous flight auger method and ready for conversion in diaphragm wall equipment

september 2021 - ONSITEUNDERGROUND 21

DRILLING

Casagrande’s new series of XP-2 hydraulic piling rigs are designed and built using the latest state-of the-art techniques

reduced pollutant emissions and minimal fuel consumption.

The hydraulic system layout, combined with specific chosen components has optimized efficiency leading to reduced load losses and fuel consumption.

The XP-2 control system offers several

The B470 XP-2 is designed to satisfy the severe European Union standards on safety and is manufactured to comply with the ISO 9001 requirements on quality

advantages for the operator including: monitoring of all working functions and parameters - diagnostics of the working systems to ensure constant monitoring of the sensor and component status - easy conversion to any drilling arrangement using the control system: there is no need

ITALIAN ABSTRACT

LA NUOVA “AMMIRAGLIA” IN AZIONE NEL REGNO UNITO La serie XP-2 di Casagrande è concepita secondo le più moderne tecniche della progettazione meccanica e comprende macchine mirate a soddisfare le esigenze delle imprese che operano nel campo della geotecnica. La B470 XP-2 è una macchina multifunzione progettata per l’esecuzione di pali con l’infissione di tubi di rivestimento, l’utilizzo di morsa giracolonna, lo scavo di pali con il metodo CFA elica continua ed è realizzata per essere rapidamente predisposta alla conversione in attrezzatura per la realizzazione di diaframmi. Grazie all’elevata coppia della rotary di 470 kNm, alle aste rinforzate e al potente argano principale, la B470 XP-2 permette una rapida esecuzione di perforazioni profonde e di grande diametro anche in terreni impegnativi. L’argano pulldown da 660 kN e la corsa di 26 m della rotary facilitano l’impiego di tubi colonna.

22 ONSITEUNDERGROUND - september 2021

for manual intervention when changing drilling settings - customization of the working parameters - remote rig assistance, diagnostics, monitoring of the working parameters.

In the XP-2 series offers the new CFM and CDR systems developed specifically for Casagrande range of foundation equipment. The CFM “Casagrande FleetMaster” is the new online platform that allows remote control from any device. With simple access to the dedicated web page, you can monitor the activity, the location of the machine, the active alarms, and the historian, all the significant data recorded as well as use and maintenance manuals and hydraulic and electrical diagrams.

The CDR “Casagrande Data Recording” is the system for recording and monitoring working parameters and drilling data. The monitor in the cabin displays the working parameters and stores the data according to the drilling technology. The data are available for download and post processing.

■

NEWS TSURUMI

Pump to replace the shovel

If you have to move loose material such as sand, mud and silt, you can safely leave the shovel behind: a Tsurumi pump with a jetting collar takes over the job. The Germanybased manufacturer now offers this optional accessory. A dewatering pump equipped with it “liquefies” the sediment so that it can be pumped.

No manual intervention is required, not even supervision. For this purpose, the jetting collar is mounted at the bottom of the pump. It functions as a ring pipe from which water is forced into the immediate suction area of the pump. Whether the material is dry or thickened: if it is mixed with sufficient water, a flowable mixture is created. With a pump like the KRS2, even mixtures with grain sizes up to 30 mm can be moved without resistance. Tsurumi has designed this unit for the toughest applications. It moves up to 4.300 litres of mixture per minute.

The process prevents clogging of the pump, which cannot be ruled out in borderline operating conditions. Deposits at the intake opening are practically impossible.

This also reduces the risk of overloading the

pump electrically and thermally. Wear and tear, and thus the risk of mechanical failure, is also significantly lower with abrasive media. Operation in basins works best, as excess flushing water is retained. A predestined area of application is

therefore sedimentation basins, sewage treatment plants and large tanks. If no pure water is available for flushing, industrial water can also be used.

It is supplied by a second pump or by connection to a water pipe. According to Tsurumi, users only need a

TM

few minutes of installation time with standard tools.

DRILLING Bauer Spezialtiefbau GmbH

The new BAUERdigital portal Digitalization in specialist foundation engineering at Bauer has steadily advanced over the last few years. A new innovative platform was created to streamline processes and day-to-day operation at the site

by Pietro Gabrielli

24 ONSITEUNDERGROUND - september 2021

I

nnovat ive appro aches and ideas – such as the b-project data management software – have increasingly automated the collection, processing, and analysis of data and progressively digitalized collaboration between all project members. The challenge: the expenditure could often not be aligned with the benefit of these new digitalization approaches when it

A new innovative platform called BAUERdigital portal was created to streamline processes and day-to-day operation at the site

Available both as a desktop application and as an app on a smartphone or tablet, the digital construction diary allows information to be recorded digitally directly on the construction site

came to small specialist foundation engineering projects. A relatively short execution period at the site was matched by comparatively high implementation costs for the digital tools.

To make the benefits of digitalization more attractive for small specialist foundation engineering projects of Bauer Spezialtiefbau GmbH, a new innovative platform called BAUERdigital portal was created to streamline processes and day-to-day operation at the site.

Project’s details “The roll out of Microsoft Teams within the Bauer Group means that each new site will have its own separate area and can be centrally and autonomously overseen by the Project Manager,” according to Torsten Henssler, project manager for Digital Construction at Bauer Spezialtiefbau. The advantage of the system is obvious, rights can be managed directly without the need for

the IT department to get involved.

The site manager appoints administrators directly and assigns user rights.

In addition to general information such as project name, order number, address, and coordinates, additional weather information and the location via Google Maps are also available.

The centerpiece of the BAUERdigital portal is made up of various application tiles that provide access to different digital tools. These applications make it possible to digitally generate reports that previously had to be painstakingly written by hand, to collect, process and analyze data, and to digitally display processes. There are currently six applications available as standard: The digital construction diary, the fielddata platform, the workflow for the site supply process, the digital delivery note Neptune, the Web BGM, and the Bauer specialist foundation engineering product catalog. september 2021 - ONSITEUNDERGROUND 25

DRILLING drilling times, tool changes, idle times, etc. is also possible.

Bauer Spezialtiefbau GmbH uses the digital web platform of fielddata.io GmbH for the documentation of smaller and medium size sites

Digital construction diary The digital construction diar y ap p l i c at i o n r e p l a c e s t h e s i t e documentation maintained by the site manager or the foremen, often tediously handwritten or maintained in Excel format. Available as a desktop application and also as a smartphone or tablet app, this information can now be captured directly on the site in digital format. It records personnel and equipment as well as working hours, quality information, work completed, and notes on delivered construction materials as well as images for documentation purposes. The major advantage: all digital construction diaries of a site are stored and compiled in an automated process – rendering manual compilation by the site manager obsolete. The information gathered is output in PDF format and can be retrieved by all participants at any time.

Fielddata Bauer Spezialtiefbau GmbH uses the digital web platform of fielddata. io GmbH for the documentation of smaller and medium size sites. With this application, data on “activity, “quality”, and “performance” can be recorded digitally and analyzed. In addition to information on the performance of the machines in use, drilling reports – socalled B reports – can be generated via the fielddata web platform. The relevant machine data and production data can then be linked and analyzed to create these reports. fielddata also provides analytics on operating hours, finished construction elements, fuel consumption, and an overall evaluation of the site production. Drilling rig operators can also record production steps including their duration and thereby furnish a detailed documentation of the construction progress. Detailed documentation of

ITALIAN ABSTRACT

LA PIATTAFORMA INNOVATIVA “BAUERDIGITAL” Approcci e idee innovativi, come i software di gestione “b-project”, stanno automatizzando sempre di più la raccolta, l’elaborazione e l’analisi dei dati in cantiere e stanno progressivamente “digitalizzando” la comunicazione tra tutti i membri attivi in un determinato progetto. La sfida attuale? I costi spesso non potevano essere allineati al vantaggio che questi nuovi approcci di digitalizzazione apportavano quando si trattava di “piccoli” progetti di ingegneria nelle fondazioni specialistiche. Per rendere più vantaggiosa la digitalizzazione anche nei progetti di ingegneria delle fondazioni specialistiche di tali dimensioni Bauer Spezialtiefbau GmbH ha creato una nuova piattaforma innovativa chiamata BAUERdigital, un portale che consente di semplificare i processi e le operazioni quotidiane in cantiere, a beneficio della produttività e dell’efficienza.

26 ONSITEUNDERGROUND - september 2021

Site supply process and Neptune Workflow integration of the site supply process into the new BAUERdigital portal makes it possible to directly request equipment for the relevant site.

With a workflow in the background, not only the actual equipment but also the relevant accessories can be requested, and the transport to the site can be organized centrally. The Neptune application is an integrated SAP add-on.

This tool was used to implement the digital delivery note.

WEB-BGM The WEB-BGM portal of the sister company BAUER Maschinen GmbH provides an overview of all currently running machines. In addition to the provision of the technical data for the respective machines, information on work assignments – where and when – and drilling methods are also provided.

Product catalog The product catalog application provides an overview of all currently available digital products of Bauer Spezialtiefbau GmbH. These are divided into four project phases, i.e. “tender phase”, “work preparation”, “execution”, and “review” and are presented with a brief description and a contact person for further questions. The aim is to provide an optimum overview of all available digital tools and applications of Bauer Spezialtiefbau. All applications provided in the BAUERdigital portal facilitate site processes without blocking them with additional expenditure and measures.

Small sites in particular therefore have the option to benefit from digitalization through their active use of these features.

Initially, the rollout of the BAUERdigital portal is planned for February to May for pilot projects in Germany to obtain direct feedback from practice. On the basis of this knowledge, all branch offices in Germany will get relevant training so that all smaller and medium sized construction projects can be processed via the BAUERdigital portal in future. ■

NEWS HERRENKNECHT

Advance record at the Brenner Base Tunnel The miners in the Brenner Base Tunnel are pushing ahead rapidly with the major rail project. On Wednesday, March 31, 2021, they achieved a new record while excavating the main tubes in South Tyrol: 860 meters of tunnel bored and lined in one month.

On the Italian construction lot “Mauls 2-3” of the Brenner Base Tunnel, three Herrenknecht tunnel boring machines (TBMs) are boring from south to north. They are excavating the two main tubes as well as an exploratory and later service tunnel 12 meters below. In March 2021, a new record was set by one of these three machines: the Double Shield TBM (Ø 10.65 meters) named “Virginia” covered 860 meters in one month. The contracting joint venture BTC S.c.a.r.l. (Astaldi S.p.A., Ghella

S.p.A., P.A.C. S.p.A. and Cogeis S.p.A.) thus achieved a peak advance rate at the Mauls jobsite.

For March 2021, the Brenner Base Tunnel project owner, AustrianItalian BBT SE, announced an average daily advance rate of 27.7 meters for “Virginia”.The daily best performance was 36.75 meters.

Dr. Matthias Flora, Sales and Project Manager at Herrenknecht, congratulated the team on the jobsite: “Our customer BTC’s crews are absolute top professionals

in their field. Congratulations and our utmost respect for this achievement!”. By early April 2021, the two machines in the Brenner main tunnels had already covered over 50% of the total distance toward their lot boundary. In stable geologies, Double Shield TBMs are predestined for good tunnelling performance. As the TBM bores, the excavated tunnel is concurrently lined with concrete segments. At a total length of 64 kilometers, the Brenner Base Tunnel being built under the direction of Austrian-Italian BBT SE will be the longest underground rail link in the world. It crosses beneath the Alps between Innsbruck in Austria and Franzensfeste (Fortezza) in South Tyrol/Italy as a particularly efficient flat trajectory, that is, with very low gradients.

YEARS 1981-2021

ANNIVERSARY

WAKE UP! GET BACK TO REALITY D re a m s a re n o t re e l , i t c a n b e re a l .

Giornate Italiane del Sollevamento e dei Trasporti Eccezionali

7-9 October 2021 Pad 1 Stand E2

Management system certified in accordance with the requirements of ISO 9001 - ISO 14001 - OHSAS 18001

19-23 October 2021 Pad 15 Stand C35

DEMAC S.R.L. | MAGENTA (MI) - ITALY | +39 02 9784488 | INFO@DEMAC.IT | WWW.DEMAC.IT

DRILLING Comacchio

News from the CH Line There is an increased anticipation for new rigs from Comacchio that will be displayed at Geofluid 2021 and in particular for the novelties of the CH line that will be presented at Piacenza. One of them, the CH 320, was introduced into the global market at the end of 2020, but has never been displayed at an in-presence event so far due to the pandemic.

The second one, the CH 150, is a new rig model that will make its debut during the fair

by Stefano Vitali

T

he CH 150 was created to meet the growing demand for compact piling machines, installed on excavator base carriers, covering a wide range of needs in foundation construction and beyond. The major advantage of this type of machines is the compact lightweight design, offering an unbeatable ease of transport and set-up, and the great versatility, based on the use of a wide choice of pile construction methodologies. In a market that increasingly requires the ability to operate in small and limited access spaces, on jobsites that cannot accommodate “conventional” piling machines, the CH 150 offers the 28 ONSITEUNDERGROUND - september 2021

possibility to perform a wide range of tasks achieving performances that are in line with those offered by larger machines.

The concept The concept is based on the use of an excavator base carrier (in the 8-10 tons weight class), equipped with a modular drilling mast and a multipurpose rotary head. To reduce size, the ballast of the excavator is kept within the footprint of the tracks. The undercarriage is expandable to facilitate transport and allow access to restricted areas.

With 2320 mm in width and 3075 mm in length, the CH 150 has an operating and transport weight of 15000 kg and is

With 2320 mm in width and 3075 mm in length, the CH 150 has an operating and transport weight of 15000 kg and is currently the smallest model in the CH series of Comacchio piling machines

currently the smallest model in the CH series of Comacchio piling machines. The CH 150 can be used for the construction of cased and uncased bored piles with Kelly system, reaching up to 1000 mm pile diameter. Thanks to a simple conversion kit, the machine can be transformed to execute CFA piles. However, the field of use of the CH 150 includes innovative applications that go beyond foundation and ground improvement projects, such as water well construction, thus opening new development scenarios for this product line.

The mast of the CH 150 is equipped with a cylinder crowd system offering 60 kN pull down/up force. The machine accommodates a main winch providing 65 kN line pull and an auxiliary winch with 27 kN line pull. The mast is mounted on a boom on the side of the cab, designed following the concept used for large excavators to give the machine greater strength and higher rigidity. The long reach of the boom, combined with the mast rotation capabilities, ensure that the CH 150 can reach a wide variety of positions, covering a large work area and reaching over obstacles.

The stability of the machine even with maximum boom reach (3600 mm), is guaranteed by the possibility to extend the undercarriage to reach 2920 mm in width. This allows to safely operate the CH 150 even on construction sites that have difficult uneven terrain. The CH 150 can be also supplied in “low headroom” configuration, designed to be used inside buildings and in low overhead clearance situations.

The modular length of the mast allows the use of kelly bars of up to 9 elements and 3.5 m in length, with a diameter of up to 419 mm and the possibility of installing different diameters on request, with minimal modifications on the machine. The rotary head equipping the machine has a compact and lightweight design and can transmit up to 43 kNm nominal torque. In kelly configuration, the CH 150 can be used for bored piles construction using dry excavation method and reaching a maximum depth of 27 m. In CFA configuration, the machine offers 170 kN extraction force and can be used to construct piles

up to 750 mm in diameter. Thanks to the use of a special extension, the maximum CFA pile depth can reach over 11 m. In addition to the construction of large diameter piles with kelly and CFA systems, the machine can be set up for micropiles installation.

The use of excavator base carriers The CH 150 is equipped with the CCS software (Comacchio Control System), allowing for real-time monitoring of operating parameters and the production process via a convenient touch screen display

The concept of the new Comacchio CH 150 is based on the use of an excavator base carrier (in the 8-10 tons weight class) equipped with a modular drilling mast and a multipurpose rotary head

that have been optimized to operate in confined spaces guarantees great ease of use and manoeuvrability in any construction site. The highly ergonomic cabin design, featuring a fully adjustable workstation equipped with proportional electro-hydraulic servo-assisted controls, has been upgraded by Comacchio with state-ofthe-art control systems based on the use of sensor technology. The use of these advanced electrohydraulic controls, supported by CAN-BUS technology, offers wide customization possibilities of the controls and the diagnostics, which significantly simplifies operations. The advanced in-cab controls integrated in the joysticks allow the operator to manage all tramming, set-up and drilling functions in an extremely simple and precise way. Like all machines of the CH series, the CH 150 is equipped with the CCS software (Comacchio Control System), allowing for real-time monitoring of operating parameters and the production process via a convenient touch screen display.

Comacchio has also brought the most modern technologies into the excavator’s hydraulic system, optimizing it for this type of use in order to ensure maximum productivity with greater energy efficiency.

The electronic control of the diesel engine by the CCS system allows the hydraulic system to obtain the maximum available power at any time, thus maximizing productivity. The cooling of the hydraulic system has been enhanced to cope with the intensive use that is typical of a drilling machine, even in the most demanding environmental conditions.

■

ITALIAN ABSTRACT

NOVITÀ DALLA SERIE “CH” DI COMACCHIO La nuova CH 150 è stata creata per soddisfare la crescente domanda di macchine di palificazione compatte, installate su supporti per escavatori, che coprono un’ampia gamma di esigenze nella costruzione di fondazioni (ma non solo). Il principale vantaggio di questa tipologia di macchine è il design compatto e leggero, che offre un’elevata facilità di trasporto e installazione, nonché la versatilità, basata sull’uso di un’ampia scelta di metodologie di costruzione dei pali. In un mercato che richiede sempre più la capacità di operare in spazi ristretti e ad accesso limitato, la CH 150 offre la possibilità di svolgere un’ampia gamma di interventi ottenendo prestazioni in linea con quelle offerte da macchine più grandi.

september 2021 - ONSITEUNDERGROUND 29

DRILLING Liebherr

Digitalization in deep foundation work The positioning system LIPOS supports continuous flight auger drilling

by Pietro Gabrielli

30 ONSITEUNDERGROUND - september 2021

E

very building stands on a solid foundation that bears the whole weight. However, when the ground below is too soft or unstable, qualified deep foundation specialists come into play in order to provide the required ground bearing capacity. With the LIPOS system, Liebherr equips the

deep foundation specialists with a tool that simplifies the task in various ways.

The Burgenland Hospital Association, KRAGES, is building a general hospital in Oberwart, Austria. The new building, in direct vicinity to the existing hospital, shall guarantee excellent medical, nursing and therapeutic care in the region. In order to avoid subsequent

settlement and damage to the new building, the available land requires substantial foundation work before it can support a whole hospital.

The company Züblin Spezialtiefbau Ges.m.b.H. was contracted to install 1,310 piles in an area of 23.000 m² for the foundation of the complete new building. All piles have a diameter of 630 mm and are being installed using the CFA (continuous flight auger) method. The maximum depth of the foundation piles is 16 m. Initially, it was assumed that a construction period of approximately 4 months would be required to complete more than 1000 piles. To complete the task, Züblin Spezialtiefbau is using a Liebherr drilling rig type LB 28, which has been equipped with the positioning system LIPOS for the first time. The LB 28 is supported on site by a Liebherr concrete

Test measurements can be carried out quickly and easily using the Rover Rod

pump type THS 110, which ensures that the delivered concrete is immediately pumped to the required location.

Once the complete building ground was exactly measured and the precise position of each single pile was

The LB 28 and the Liebherr concrete pump type THS 110 from Züblin Spezialtiefbau Ges.m.b.H. on the jobsite in Oberwart

september 2021 - ONSITEUNDERGROUND 31

DRILLING

The exact position of the Liebherr machine is constantly displayed on the additional LIPOS monitor in the cab

The LIPOS antennae are mounted directly on the leader and allow for centimetre precision in positioning

identified, the gathered data could be transferred as a digital drilling plan to the LIPOS positioning system in the Liebherr machine in no time. Jobsite data and pile lists for work to be carried out are transferred to the machine when the drilling list is uploaded.

The operator sees his position with centimetre precision at all times thanks

to an additional monitor in the cabin.

The LB 28 can be manoeuvred with ease to each of the 1,310 drilling points without the need of any iron stakes or colour markings for orientation.

The operator no longer has to watch out for ground markings or the concrete hose. He can concentrate on important things, is more flexible and

ITALIAN ABSTRACT

DIGITALIZZAZIONE NELLE FONDAZIONI PROFONDE Ogni edificio poggia su solide fondamenta che ne sopportano l’intero peso. Tuttavia, quando il terreno sottostante è troppo morbido o instabile, entrano in gioco specialisti qualificati in fondazioni profonde per fornire la capacità portante richiesta. Con il sistema LIPOS, Liebherr fornisce agli specialisti delle fondazioni profonde uno strumento che semplifica il compito in molti modi.

Un esempio? L’associazione ospedaliera del Burgenland, KRAGES, sta costruendo un ospedale generale a Oberwart, in Austria. Il nuovo edificio, nelle immediate vicinanze dell’ospedale esistente, garantirà un’eccellente assistenza medica, infermieristica e terapeutica nella regione. Per evitare successivi assestamenti e danni al nuovo edificio il terreno disponibile necessita di consistenti opere di fondazione prima di poter sostenere un’intera struttura. L’impresa Züblin Spezialtiefbau Ges.mbH è stata incaricata di installare 1.310 pali in un’area di 23.000 m² per la fondazione dell’intero nuovo edificio. Tutti i pali hanno un diametro di 630 mm e vengono installati con il metodo CFA. La profondità massima dei pali di fondazione è di 16 m. La perforatrice Liebherr è stata equipaggiata con il sistema LIPOS ed è pronta per sostenere tutte le esigenze della nuova era digitale.

32 ONSITEUNDERGROUND - september 2021

independent, and therefore, quicker in handling the drilling rig. Furthermore, the system simplifies the positioning of jobsite equipment. The concrete pump, the reinforcements, as well as other tools and material can be optimally positioned around the drilling rig.

An above-average daily drilling performance is achieved using the LB 28 and the construction work could be completed earlier than planned, actually after only 3 months. One reason, in addition to the reliable Liebherr construction machine, is the extremely productive working method.

The LIPOS positioning system plays a decisive role here. Without this system the drilling points would have to be newly measured, drawn and marked at least three times a day. An enormous additional effort which is completely eliminated with the help of LIPOS. All jobsite personnel has a clear overview at all times of exactly where the piles are, which piles are already completed and which still have to be done. One thing is clear for the site manager Harald Fugger following his experience on the jobsite in Oberwart, “The LIPOS positioning system is ideally suited for completing jobsites, especially using the CFA method. It has proven itself well on the jobsite and makes working processes easier allowing continuous real time control and monitoring. Quality management is considerably improved through the automatic recording of the processes. The LIPOS system is basically self-explanatory for the operator and convinces through easy handling.” ■

TUNNELING Sennebogen

Two duty cycle cranes for RTE Special civil engineering company Spie Batignolles uses two Sennebogen 6140 E duty cycle cranes to remove high voltage power lines and put them underground

by Stefano Vitali

T

he Réseau de Transport d’Electricité (RTE) operates the French transmission network for electricity and is currently installing 4 underground power lines of 225,000 volts between the communes of Saint-Denis, Île Saint-Denis and Villeneuve la Garenne. By 2024, 15 km of overhead power lines and 27 pylons will be removed, making more than 80 hectares of land available for development and building. Later, the Olympic village for athletes will be built in Saint-Denis. For this purpose, a 2.5 km long underground tunnel will be drilled in Saint-Denis in 2021.

The first stage of this major project is the construction of boreholes that will allow the tunnel-boring machine to be lowered. With on-site support: two 140 t Sennebogen duty cycle cranes with XL hydro-milling machine and diaphragm wall grab. Thanks to the high load capacity of 24 t at a working radius of 20 m, heavy attachments can be operated in grab operation - certainly with guaranteed maximum stability thanks to the robust wide-track undercarriage.

34 ONSITEUNDERGROUND - september 2021

ITALIAN ABSTRACT

DUE GRU SENNEBOGEN 6140 E PER RTE Réseau de Transport d’Electricité (RTE) gestisce la rete di trasmissione dell’elettricità francese e sta attualmente installando quattro linee sotterranee da 225.000 V tra i comuni di Saint-Denis, Île Saint-Denis e Villeneuve la Garenne. Entro il 2024 saranno rimossi 15 km di linee elettriche aeree e 27 tralicci, rendendo disponibili oltre 80 ettari di terreno per lo sviluppo di altre tipologie di costruzioni.

Successivamente, a Saint-Denis sarà costruito il Villaggio olimpico per gli atleti.

A tal fine, nel 2021 a Saint-Denis sarà realizzato un tunnel sotterraneo da 2,5 km di lunghezza. La prima fase di questo grande progetto è la realizzazione di pozzi che consentiranno l’abbassamento della TBM che andrà a operare nel sito e ciò è reso possibile anche dall’utilizzo di due gru Sennebogen “Duty Cycle” da 140 t dotate di idrofresa XL e diaframma.

september 2021 - ONSITEUNDERGROUND 35

TUNNELING of Paris, as they supply around 800,000 households, including the train station Gare du Nord and Line 13 of the Paris Metro. To meet all these challenges, RTE has chosen a technical solution that is tailor-made and exceptional for an electricity distribution network operator: the construction of a 40 m deep tunnel to run the new lines. For the realization of this tunnel, RTE relies on the expertise of Arcadis as deputy project managing company and on the consortium of the companies Spie Batignolles Fondations, SETEC and SPAC and its representative Spie Batignolles Génie Civil.

The two Sennebogen 6140s from Spie Batignolles Fondations are equipped with XL hydro-milling machine and diaphragm wall grab

The maximum load capacity of the machines is 140 t. This major project is located in a highly urbanized area, bounded by several railroad and

waterway lines, where extensive work will take place until 2024. Also affected are power lines that are essential for the electricity supply of the northeast

In operation with the 6140 E At t he const r uc t ion site, Spie Batignolles Fondations is using its two Sennebogen 6140HD duty cycle cranes, which were recently delivered by sales and service partner SYGMAT. One of them is equipped with a powerful XL hydro-milling machine developed

by Spie Batignolles Fondations itself.

The 6140HD’s 708 kW engine and generously dimensioned hydraulic

A 613 E CRANE IN THE MINE Mining is one of the most traditional

suitable individual parts for transporting

Fully mounted, the modular telecrane

industries in Germany and the world.

it through the shaft to a depth of 180 –

proves to be a perfectly equipped tool

Also, at the Heilbronn rock-salt mine,

200 m. After that, it was reassembled on

for underground work thanks to the extra

salt has been extracted from salt layers

site together with the service technicians

compact yet three-part 14.6 m telescopic

up to 50 meters thick for more than 125

of the responsible dealer Schwab GmbH

boom, individual software adaptations

years. In addition to the extraction of

Baumaschinen & Baugeräte.

and the electrical and hydraulic packa-

raw materials, however, waste disposal is also an important business area of the mine. Waste materials are treated safely and maintenance-free and then recycled or disposed of. For a long time now, the miners have been supported by powerful machines and the latest technologies - also from Sennebogen.

Recently, they welcomed a new 613 E telescopic mobile crane in their fleet, which, thanks to its compactness and flexibility, is perfect for demanding underground operations. In order to reach its underground destination, the 16 t mobile crane therefore first had to be prepared accordingly. At the manufacturer’s the 613 E was dismantled into

36 ONSITEUNDERGROUND - september 2021

The 140 t duty cycle cranes are used to construct the entrance and exit shafts for the tunnel-boring machine

ges particularly designed for the salt

ne is now primarily used as a stacking

mine. The overall height of the machi-

vehicle for moving big bags of waste

ne, including the FOPS protective roof

materials weighing up to 2 tons, so

grating on the cab, is only 3.28 m, so

that they can be handled and dispo-

that the crane fits easily into the hollow

sed of in a long-term safe and envi-

spaces. The 16 t telescopic mobile cra-

ronmentally friendly manner.

pumps drive this impressive attachment.

The second Sennebogen duty cyle crane is equipped with a powerful diaphragm wall grab. Its 350 kN free-fall winches are adapted to the size of the grab and the massive cylindrical walls to be built for this shaft.

Currently, the construction of the entrance and exit shafts for the tunnelboring machine is taking place. The entrance shaft is located near Volta street in Saint-Denis. In 2021 the 2.5 km long tunnel will be drilled by the tunnel-boring machine so that in 2022 the new power lines can be installed and connected. This is followed by the dismantling of the pylons and overhead lines from 2023 to the end of 2024. The approximately 80 hectares of land that can be developed by these underground construction works will be used to accommodate new urbanized areas in the North of Paris.

■ september 2021 - ONSITEUNDERGROUND 37

TUNNELING Robbins

OFTA process in China

38 ONSITEUNDERGROUND - september 2021

China’s largest Robbins Crossover TBM was launched in late March 2021 to bore the 2.5 km (1.6 mi) long Pazhou Line Lot PZH-1 of the Pearl River Delta Intercity Railway Project

by Pietro Gabrielli

T

he largest ever Crossover (XRE) TBM in China launched in late March 2021 in Guangzhou for contractors Sichuan Jinshi Heavy Equipment Leasing Co., Ltd and CREC Bureau 2. Onsite First Time Assembly (OFTA) was utilized to build the 9.16 m (30 ft) diameter Robbins TBM, taking just five months from the start of assembly to machine launch. The hybrid machine is boring the 2.5 km (1.6 mi) long Pazhou Line Lot PZH-

1 of the Pearl River Delta Intercity Railway Project, which will offer better commutes for Guangzhou residents traveling to and from University City.

The machine will encounter various ground types during its bore, from moderately to strongly weathered argillaceous shales and sandstone to mixed face conditions. Much of the rock is fractured, while the quartz content is as high as 50 percent. “Not only are there poor ground conditions such as soft to hard uneven, fractured zones and full-

face hard rock, but these sections appear to alternate frequently, which is the biggest challenge of the project. It will be a test of performance and tunneling efficiency for the machine,” said Yongsheng Qi, Project Manager for Robbins China.

The tunnel is also expected to cross under rivers and other bodies of water with a cover of 20 to 31 m (65 to 100 ft).

The ground strata connects to the river and is highly permeable, resulting in expected water pressures above 7 bar.

The project’s success lies in stabilizing the water pressure at the face while ensuring acceptable advance rates and construction safety.

TBM features The Crossover TBM features both hard rock and EPB modes and is optimized for the rapidly changing ground found on the project. An adaptable cutterhead

China’s largest Robbins Crossover TBM launched in late March 2021 to bore the 2.5 km (1.6 mi) long Pazhou Line Lot PZH-1 of the Pearl River Delta Intercity Railway Project. The 9.16 m (30 ft) diameter Robbins Crossover (XRE) TBM was built using Onsite First Time Assembly (OFTA)—a process that took just five months from the start of assembly to machine launch september 2021 - ONSITEUNDERGROUND 39

TUNNELING MEGA-SIZED CROSSOVER MACHINE RAMPS UP IN TURKEY A Robbins 13.77 m (45.18 ft) diameter Crossover XRE TBM launched recently in spring 2021 in Eşme, Turkey. The large machine is boring the 3.05 km (1.90 mi) Eşme-Salihli RailwayTunnel through mixed conditions including sandstone, gravelstone, claystone, and siltstone. Contractor Kolin Construction expects some occasional groundwater and weak rock between 5 to 9 MPa (720 to 1,300 psi) UCS, with the potential for a gassy environment. The titanic TBM was launched after more than seven years in storage, and following a few upgrades to systems to ensure they meet the newest safety and efficiency standards. “I am very happy that the TBM has been launched. Up to now, the machine has bored nearly 500 m (1,600 ft) in gneiss and mudstone. This is an opportunity for Robbins to prove that large diameter TBMs can bore in such tunnels, even in

The machine is optimized for rapidly changing conditions with two-speed gear reducers known as the Robbins Torque-Shift system for efficient tunneling in hard, mixed, and soft ground

very complex geology and difficult ground conditions,” said Yunus Alpagut of ATES, Robbins’ Turkish subsidiary. Alpagut went on to explain why the project is so important: “Recently, there have been large diameter, non-Robbins machines that have failed at projects such as the high-speed railway in Bilecik, so this is very important to show the Turkish tunneling industry that large machines are up to the challenge.”

design and two-speed gear reducers known as the Robbins Torque-Shift system enable efficient tunneling in hard, mixed, and soft ground.

An adaptable screw conveyor can be mounted in the center or bottom of the mixing chamber depending on the mode. To combat high water pressures the machine is fitted with high pressure seals and can statically hold up to 30 bar. The XRE TBM began its excavation in EPB mode and will shift to hard rock mode to continue excavation after 1.5 km (0.9 mi) has been bored.

The unique project is one of several 40 ONSITEUNDERGROUND - september 2021

mixed ground operations using Robbins Crossover TBMs in China. Two 6.91 m (22.6 ft) diameter XRE machines are currently boring sections of the Chongqing Metro Phase 2 in ground conditions ranging from weathered mixed granite to weathered pegmatite and adamellite. The project is under the same contractors as the Pearl River Delta bore. “At the Chongqing Metro project, we won the trust of the contractor with the performance of the Crossover machines; to date the highest monthly advance rate in Chongqing is 365 m (1,197 ft). This is one of the main reasons the contractor again selected a Robbins Crossover TBM for the Pearl River Delta project,” observed Qi. With rates at Chongqing Metro as a precedent, the Pearl River Delta tunnel is scheduled to be completed by the end of 2021 and put into operation in 2023.

■

ITALIAN ABSTRACT

UNA TMB ROBBINS IN AZIONE A GUANGZHOU La più grande TBM Crossover (XRE) mai utilizzata in Cina è stata fornita alla fine di marzo 2021 a Guangzhou per mano degli appaltatori Sichuan Jinshi Heavy Equipment Leasing Co., Ltd e CREC Bureau 2. Nella fattispecie, è stato utilizzato il sistema Onsite FirstTime Assembly (OFTA) per costruire gli oltre 9 m di diametro con la TBM Robbins, facendo trascorrere solo cinque mesi dall’inizio dell’assemblaggio all’avvio della macchina. LA TBM sta perforando il lotto PZH-1 della linea Pazhou lungo 2,5 km nell’ambito del progetto ferroviario interurbano del delta del fiume Pearl, che garantirà un miglioramento negli spostamenti ai residenti di Guangzhou che viaggiano da e verso la città universitaria.

NEWS KELLEY E.E.

Partnership with Roxard Industries Kelley Engineered Equipment and Roxard Industries formed an alliance in North and South America. This new partnership combins forces to meet the growing demand for rolling disc cutters, soft ground tools and cutter rebuild services for tunneling and mining projects in North and South America.

Roxard Industries is an OEM manufacturer of high quality, long lasting consumables, and custom products for tunneling and mining applications in soft ground, hard rock, and mixed face conditions. In addition to hard parts and spares, Roxard also offers disc cutter rebuilds, TBM cutterhead refurbishment and custom manufacturing services. Kelley Engineered Equipment specializes in the design and manufacture of custom tunneling equipment, lifting systems, mucking systems, pipe carriers, custom tunneling shields, custom attachments, conveyors, equipment modifications, personnel access systems and professional engineering services. Both companies pride themselves on their reputation for high quality and record of on time delivery - On time, every time.

Roxard Industries and Kelley Engineered Equipment have entered into this agreement for the supply of Tunneling cutters and consumables in North and South America. Under this agreement, they will provide with complete cutterhead consumables and services, ensuring: rapid delivery and quick turnaround of custom solution, local sales and service with spare parts inventoried in the USA and disc cutter rebuild service in American workshop of at the jobsite.

Leister Technologies Italia Srl Via T.A.Edison, 11 | 20090 Segrate (Mi) Tel.: 02-2137647 | info@leister.it

www.leistershop.it

GEOSTAR G7 Potenza e controllo nell’ingegneria sotterranea

La saldatrice automatica GEOSTAR G7 è utilizzata per saldare geomembrane nella costruzione di discariche o in tutte le opere di ingegneria sotterranea.

Grazie al sistema LQS si possono registrare e monitorare tutti i dati sulla saldatura.

www.leister.com

We know how.

TUNNELING Sandvik

New machines, new capabilities The DT923i is a new automated tunneling jumbo delivers high drilling power, safety and operational savings.

Equipped with new SB110i booms, this drill rig provides exceptional side coverage, features for fully-automated face drilling, boom control systems and comprehensive tools for drill planning, reporting and analyses

by Ettore Zanatta 42 ONSITEUNDERGROUND - september 2021

S

andvik Mining and Rock Solutions has launched the new Sandvik DT923i jumbo, its latest development drill rig for high power face drilling in tunnel and cavern excavations. Together with the new RD5 series high frequency rock drills and rock tools designed for high speed drilling, it delivers uncompromised accuracy and productivity.

An automated tunneling jumbo The new Sandvik DT923i is an automated iseries tunneling jumbo with two electrohydraulic booms providing the highest levels of performance and reliability. The computer controlled rig’s automatic drilling functions and operator controlled boom positioning make it ideal for face drilling. As well as incorporating some of Sandvik’s

latest developments in information technology solutions, the new rig uses Sandvik’s new RD5 series high frequency rock drills. It has fast and automatic rod handling, an ergonomic cab and a powerful yet economic carrier, making it a comprehensive high speed drilling solution. Designed to maximize operator safety and ergonomics, Sandvik DT923i also has high parts commonality with other Sandvik drill rigs. The rig’s new SB110i uses Sandvik’s patent pending stiff square shape boom technology, optimized with a front wrist structure that effectively provides up to 62 percent more side coverage whilst using a new fully proportional boom control for accurate and fast manual boom handling, delivering operational savings when tunneling. The rig also features an optional boom collision prevention and avoidance package.

A new software The DT923i comes equipped with some of the latest developments in information technology based face drilling automation: Sandvik has launched an updated version of iSURE, its purpose developed excavation process control underground rock excavation software for providing instrumented face drilling rigs with the necessary information for optimized drilling and blasting. iSURE works seamlessly with Sandvik’s iseries drill rigs, providing an accurate analysis functionality to improve the work cycle and process.

The iSURE (Intelligent Sandvik Underground Rock Excavation) software is a world renowned computer program for tunneling construction and mining drill and blast process control. It helps produce data needed for optimizing the drilling and blasting cycle, capitalizing the accuracy of Sandvik’s advanced iseries rigs, being designed to be used according to the specific and diverse needs of the user and the specific application efficiently. iSURE 8.0 version The iSURE 8.0 added a template based drill and blast plan generation

Sandvik DT923i comes equipped with some of the latest developments in information technology based face drilling automation

tool that takes in to account rock blastability, tunnel profile quality target and explosives used, however not forgetting designer capability to easily edit and tune the result based on the feedback of the drill and blast process. As before, iSURE focuses on blasting design at round’s bottom, as that is the point where blasting is most critical. The iSURE enables drill rig usage and drilling process efficiency to be maximized, assessed and measured

on a round by round basis. Counters of rig’s production capability, data of how well drilling was done versus the plan, realized face shape of the previous round, measure while drilling (MWD) data, achieved blasting pullout, presenting scanned tunnel profile and data from geological interpretation are all available, providing valuable feedback that helps to fine tune the rig’s behavior, while also acting as a learning tool for operators.

New Sandvik DT923i tunneling jumbo improves accuracy and productivity

september 2021 - ONSITEUNDERGROUND 43

TUNNELING

The new Sandvik DT923i is an automated iseries tunneling jumbo with two electrohydraulic booms providing the highest levels of performance and reliability

New extensive features Sandvik’s avowed aim is to provide drill and blast professionals with an updated version of iSURE each year. This is being done to reflect the constant changes that tunnelers face each day, as well as reflect Sandvik’s close and integrative relationship with its customers. As such, iSURE 8.1 now includes an inbuilt threeday training program to cover steps from simple concepts to the more advanced cases. A key development sees iSURE 8.1 having a toolset for specifically

covering ‘advanced metrics’. This helps the user increase knowledge and reveal points of improvement in face drilling rigs usage and in tunnel excavation drill and blast process via producing high level KPIs from collected rounds and respective design data. These consist of production, realized schedule and heuristics analysis of the data addressing the feedback received regarding version iSURE 8.0. They are targeted to improve excavation (face drilling) production capability, plan future activities such as new projects

ITALIAN ABSTRACT

NUOVE MACCHINE, NUOVE OPPORTUNITÀ Il carro di perforazione Jumbo ad alta prestazione Sandvik DT923i è progettato per eseguire i lavori di avanzamento in gallerie e cunicoli. La perforatrice, dotata di martello perforatore ad alta frequenza della serie RD5 e di utensili concepiti appositamente per eseguire perforazioni ad alta velocità, offre elevata precisione e produttività. La DT923i è una perforatrice automatizzata della serie “i” di Sandvik, dotata di due bracci elettroidraulici in grado di offrire un elevato grado di rendimento e affidabilità. La perforatrice è computerizzata, provvista di funzioni automatizzate, con posizionamento del braccio gestito dall’operatore, ed è ideale per le fasi di avanzamento in galleria. La DT923i contempla alcune delle funzioni più all’avanguardia nell’ambito della tecnologia informatica - come il sistema iSURE (Intelligent Sandvik Underground Rock Excavation) - e impiega i martelli perforatori ad alta frequenza della serie RD5 di Sandvik Mining and Rock Solutions. Dispone inoltre di un sistema di prolungamento rapido e automatizzato delle aste di perforazione, di una cabina ergonomica e di un veicolo portante performante.

44 ONSITEUNDERGROUND - september 2021

and to raise awareness when problems or difficulties occur. The metrics have been designed for both mining and tunneling applications.

Empowered drill and blast The new and existing features found with iSURE 8.1 are designed to improve the entire drill and blast process through data collection. It will also hint if any rig adjustment is required, or if rig misuse is suspected. It shows the change in rock mass drillability, drill steel consumption, face shape after blasting and scaling, any operator deviation from the plan whilst drilling, and based on scanner data, the realized profile and production volume is shown. All that and more are available directly at the designer’s fingertips, resulting in improved production and productive feedback that can be assessed and built upon, empowering the entire drill and blast process. The iSURE 8.1 is not the final development of this leading solution from Sandvik. New improvements and developments are planned based on further sharing of knowledge and experience with customers and drill and blast professionals globally. Currently iSURE is used with Sandvik’s iseries face drilling rigs, the original Construction iseries and newer Bedrockstyle iseries, TCAD+ instrument and bolting instrument.

■

TUNNELING Epiroc

Next generation in underground mining With protected hydraulics, sensors and cables, Epiroc’s new Boomer M20 is designed and built to minimize unplanned stops and maximize uptime and performance in highly demanding operations

by Ettore Zanatta

46 ONSITEUNDERGROUND - september 2021

A

cha l l e ng i ng p ar t of underground work is the everyday wear and tear on hydraulic hoses. Falling rocks and debris and the continuous wear against tunnel floor and walls means constant hose repairs.

The Boomer M20’s heavy duty hose-less boom design minimizes unplanned stops for hose repairs, keeps the rig up and running even in the toughest conditions.

“The Boomer M20 has been developed in close collaboration with key customers and is the result of extensive research and real-world testing. This is the perfect choice for mining houses and contractors that wants to out-drill the competition through innovation”, says Niklas Berggren, Global Product Manager Face Drilling Equipment at Epiroc.

The Boomer M20’s heavy duty hose-less boom design minimizes unplanned stops for hose repairs, keeps the rig up and running even in the toughest conditions

september 2021 - ONSITEUNDERGROUND 47

TUNNELING in mind, thanks to several features the rig secures a safe working environment for operators. “Safety has been with us since day one. It’s our top priority and we have made great efforts in improving safety for operators with this rig,” Niklas Berggren says. Through teleremote capabilities, operators can drill from a safe distance away from hazardous areas at the tunnel face and keep production going also over shift changes.

Thanks to the multi-functional joysticks operators can keep their eyes on the task at all times. The unique cabin is designed to give optimum visibility and thanks to noise and vibration dampening materials, the noise level is kept as low as just 65 decibels. The safe bolting platforms is another great advantage that avoids any operation under an unsupported rock.

Epiroc continues the charge towards electrification in underground mining and the new Boomer M20 comes with a battery-electric driveline option

Reliability and quality High precision and performance are ensured thanks to on-board automation features, tele-remote capabilities and digital drill plans which give higher reliability and quality of the full drill cycle. By utilizing High Performance Development, the Boomer M20 allows the operator to adjust and download drill plans directly at the face which

eliminates the need for adjustments on the surface. “With digital drill plan handling, drill rounds will be longer, more precise and give far less overbreak. We have seen total cost savings of up to 25% and up to 40% productivity increase”, says Niklas Berggren.

Safer work environment The Boomer M20 is designed with safety

ITALIAN ABSTRACT

UN NUOVO BOOMER PER IL SETTORE MINERARIO Boomer M20 è il primo carro di perforazione da galleria al mondo con idraulica protetta. Con idraulica, elettronica e sensori protetti, infatti, il nuovo Boomer M20 di Epiroc è progettato per ridurre al minimo gli interventi di manutenzione non programmati e per massimizzare i tempi di attività e le prestazioni. Il design del braccio del Boomer M20 con l’idraulica posta all’interno riduce al minimo i fermi macchina per la sostituzione dei tubi idraulici, mantenendo la perforatrice in funzione anche nelle condizioni più difficili. “Il Boomer M20 è stato sviluppato in stretta collaborazione con i principali clienti ed è il risultato di un’ampia ricerca e di test in ambiente reale. È la scelta ideale per le miniere e per i contractor che vogliono superare la concorrenza grazie all’innovazione”, afferma Niklas Berggren, Global Product Manager Face Drilling Equipment di Epiroc. Il Boomer M20 è stato progettato pensando anche alla sicurezza e all’elettrificazione, infatti può essere fornito con alimentazione elettrica a batteria.

48 ONSITEUNDERGROUND - september 2021

Battery driveline option Epiroc continues the charge towards electrification in underground mining and the new Boomer M20 comes with a battery-electric driveline option.

A battery powered Boomer M20 brings additional savings on health, maintenance, ventilation and cooling.

“With the on-board charger, the operator does not need to plan for charging, as it automatically takes place while connected to the grid for drilling. Thanks to the high capacity battery, Boomer M20 has a fantastic driving range, and there is nothing to disturb the drift cycle”, says Niklas Berggren.

Mining from a new perspective To really highlight the fantastic innovation, a spectacular campaign video has been produced, with a scenic backdrop that will take your breath away. The Boomer M20 is balancing on its innovative, robust booms, on a mountain top. Breathtaking without a doubt. Epiroc’s President and CEO, Helena Hedblom, is fronting the new innovation in the campaign video: “We are in this for the thrill of solving the real problem. For the adventure and energy found in new perspectives. The Boomer M20 is another great example of how we make a difference through innovation”. ■

EQUIPMENT Tecniwell

Electrical innovation The Piacenza-based manufacturer - which boasts a leading position in the field of special equipment for soil consolidation and, particularly, jet-grouting applications - has recently embarked on the process of diversifying its production and has launched a new line of electric pumps on the market

by Stefano Vitali

T

ecniwell, Italian company based in Podenzano (PC), was founded in 1987 with a special focus on the production of equipment for soil consolidation and, mainly, jetgrouting, a field in which the company manufactures High Pressure Triplex Pumps (400 to 550 bar average range) with flow rates up to 900 l/min. Today, after over 30 years of activity, Tecniwell ranks as a global market leader in the 50 ONSITEUNDERGROUND - september 2021

design and manufacture of products intended for this “landmark” sector in the company’s history and is also a key player in the production of various types of mixing plants, multipurpose drilling rigs, fluid pumping solutions for the Oil&Gas industry (motor pumps with flow rates over 1,000-1,500 l/min and pressures up to 350 bar), for directional drilling, water and geothermal deep well drilling (delivery rates over 2,000 l/min and pressures up to 100 bar). Since

its establishment the company has delivered more than 4,000 units, with a wide range of features and performance levels, which are in daily use on the most challenging soil consolidation and/or oil industry sites across all continents, from Europe to Africa, America, Asia and Oceania.

New line with electric motor drive Tecniwell has recently launched a new

This innovation maximizes torque uniformity (a distinctive feature of these motors) and allows unprecedented versatility of use, integrating and further consolidating the enhanced performance and reliability of these pumps. The final result was extremely satisfactory and led to the creation of a product featuring ultra-silent operation and low environmental impact, thus successfully responding to the increasing need to reduce noise pollution and emissions.

A product range steadily expanding Tecniwell uses top quality steels and heat treatments for the production of the main mechanical components of the motor pumps. Equipment design and assembly - which take place at the two facilities in Podenzano and Piacenza, covering a total area of approx. 4,000 m2, with a workforce of over 50 people - are also based on criteria of simplicity and rationality. By virtue of the construction features, this equipment ensures high levels of performance in

MOTOR PUMP NO. 1000 During our visit to the production facility of Podenzano, High Pressure Triplex Pump Model TW 800, which is Tecniwell’s No. 1000 pump, was nearing completion. Recently delivered to a customer in the United States, this equipment - the manufacturer’s core product – stands out for all the performance and reliability features that are peculiar to the production of the Piacenza-based Tecniwell has launched a new line of electric pumps with a view to complementing its product range, consolidating the company’s leadership in the sector and reaffirming a strong commitment to environmental sustainability

company. Motor pump TW 800 No. 1000 is fitted with an 800 HP Scania engine, which allows the pump to run at an operating pressure of 460 bar with a delivery rate of 800l/min.

line of pumps, kick-starting an ‘’electrical innovation’’ with a view to extending and complementing its product range, consolidating the company’s leadership in the sector and, in parallel, reaffirming a strong commitment to environmental sustainability. On this occasion, the Emilian company has designed and implemented an innovative mechanical gearbox/electric motor drive system controlled by an inverter powering a traditional pumping unit. september 2021 - ONSITEUNDERGROUND 51

EQUIPMENT

Tecniwell uses top quality steels and heat treatments for the production of the main mechanical components of the motor pumps; equipment design and assembly are also based on criteria of simplicity and rationality

(containerized plants, in particular, are equipped with a load-bearing structure capable of supporting the load generated by the stacking of TW horizontal cement silos). The company also manufactures equipment for grouting projects and a range of low/medium pressure pumps driven by electric or diesel engines with power rating from 3 to 55 kW. Tecniwell has furthermore developed pumping systems (triplex pumps and horizontal

“

TECNIWELL HAS PRESENTED A NEW LINE OF PUMPS, KICK-STARTING A PROCESS OF ‘ELECTRICAL INNOVATION’

ITALIAN ABSTRACT

INNOVAZIONE ELETTRICA Tecniwell ha presentato al mercato una nuova linea di pompe dando il via all’“innovazione elettrica”, con l’intento di ampliare e completare la serie dei suoi prodotti, di consolidare la sua leadership nel settore e di confermare il suo impegno nella sostenibilità ambientale. L’azienda emiliana ha progettato e realizzato un innovativo accoppiamento cambio meccanico/motore elettrico regolato da un inverter che aziona un tradizionale gruppo pompante. Un’innovazione che sfrutta l’uniformità di coppia (peculiarità di questi motori) e permette una flessibilità d’uso mai raggiunta prima, completando e consolidando la superiore produttività e affidabilità delle sue pompe. Il risultato finale ha portato allo sviluppo di un prodotto caratterizzato da un’estrema silenziosità e un basso impatto ambientale, rispondendo così con grande efficacia alle crescenti esigenze di riduzione dell’inquinamento acustico e dell’abbattimento delle emissioni. Nel frattempo l’azienda piacentina ha completato e consegnato la motopompa TW 800, la n. 1.000 di casa Tecniwell.

52 ONSITEUNDERGROUND - september 2021

injectors) with outstanding performance as to delivery rate and pressure for use in oil, water and geothermal well drilling.

Many national and international oil companies praise the high quality, safety and performance standards of Tecniwell’s equipment, which made the company one of the most reliable suppliers in this field, in terms of quality and suitability of the technical solutions adopted. High-pressure

“

terms of reliability and durability. In brief, Tecniwell can now offer a wide range of solutions for use in multiple fields of applications. Let’s mention, first of all, jet-grouting equipment, rods and tooling: design and production of highpressure motor pumps comply with high standards of safety, productivity and reliability; high-quality steels and heat treatments are used for powerends and fluid-ends; drive systems can be internal combustion or electric, with mechanical gearboxes and clutches or with torque converters. Mixing plants for back-filling (tunnelling) can be fully synchronized with the TBM Control Room and are designed to meet output requirements from 5 to 200 m 3/h

triplex / quintuplex pumps for the oil drilling sector are often complemented by pumping water filtration, dilution and treatment units, by units for mixing, dosing and injection of chemical additives and by filtration units. The TW product range includes multifunctional hydraulic drill rigs designed for optimal jetting execution, with diesel or electric motors with output of 110 KW (150 HP) and 245 KW (325 HP). In addition to all this, Tecniwell is also committed to the creation of “customized” products: based on its extensive knowhow, the company studies, designs and manufactures special equipment intended to solve and alleviate peculiar on-site problems whether above or below ground.

■

CASING SIP&T

To work safe and fast!

As a result of a constant innovation, the robust and universal Automatic Casing Driver Adapter designed and patented

by SIP&T can be easily fitted to all drill-rigs and no further adjustments are necessary. It does not only ensure safe work, but leads to enormous timesaving when drilling cased boreholes

by Stefano Vitali 54 ONSITEUNDERGROUND - september 2021

T

he Automatic Casing Drive Adaptor made by the SIP&T represents an interesting locking system for casings that can be used on all piling rigs and can increase the safety and productivity in the execution of cased piles, by avoiding any damages and loss of time caused by the manual locking phase.

It is easy to use because its functioning is completely mechanic; the automatic driver will be locked to the casing column whenever the casings are going to be moved in/outside the borehole.

In that way the imperative “safety first” is respected, and also damages on the casings are excluded avoiding downtime and saving repair costs. Its affordability, customization, immediate deployment, easy maintainability and emergency system, guarantee a very high return on investment.

Why use the Auto CDA During cased drilling operations (using casings) it is often necessary that some workers on site operate in high positions. Before starting the drilling operation, the casing elements must be fixed into the ground; for this purpose, the elements are connected by threaded bolts in a safe manner, in order to create the whole column.

The same column must be bolted to the rig rotary head through a casing drive adaptor. When the drilling hole is completed, casings must be removed from the ground and then dismantled element after element. Generally, to connect the casing column to the driver, the locking pins are manually fixed, as result the worker is forced to use some stratagems such as a ladder, a wheel loader - used as a “work platform” - or a harness.

These solutions, even widespread, are not safe. The ladder could slide or slip on the muddy ground (during drilling there are no neat and clean ground surface); the worker could fall down from the ladder (because of their dirty boots); from an unstable position on the ladder, the operator must carry out their work with great physical effort; even the wheel loader operator could do an unintentional wrong movement, so as to endanger the life of the worker; the harnesses could

fail and therefore cause the worker to fall down. The use of these devices are not only risky for the personnel safety but highly unproductive, since the whole workers team - and the piling rig operator - can’t work until the casing column is completely connected to casing drive adaptor (in turn connected to the rotary head) or vice versa until the column is completely disassembled.

To overcome all these problems SIP&T decided to go to the origin of the problem and develop a device that would represent the definitive solution: the automatic casing drive adaptor (called Auto CDA).

What it is and how it works The system has been designed and built internally and entirely by the company located in Baronissi. It is applied to the casing pipes that SIP&T itself manufactures and is compatible

with all the casings produced by other companies. It is an automatic casing connector system that can be used with any type of piling rig and its greatest advantage is the ability to increase both safety and productivity in foundation works, eliminating both the related dangers and the huge amount of time necessary for the jointing of the casing pipes that until now was often performed manually. The casings are made of high quality steel and are proposed for the construction of foundation works in soils that require the covering of the hole, intended to be drilled, which otherwise could collapse. The Auto CDA performs by a mechanical locking/unlocking system of the two male/female joints generally positioned at the extreme of two casing pipes, which must be coupled or used, as said earlier, on any model of drilling machine, also of large torque.

The Auto CDA D.880 mm in top down position attached to a rotary with 240 kNm max torque

september 2021 - ONSITEUNDERGROUND 55

CASING

The operator is able to dis/connect the casing column to the Auto CDA without any other personnel help, so they can directly manage the work from the piling rig cabin

The system is directly controllable from the rig cabin and all the manual operations carried out so far by the site personnel can become a distant memory, with undisputed advantages both for the safety and for the casing arrangements and the piling rig itself.

ITALIAN ABSTRACT

LAVORARE IN RAPIDITÀ E SICUREZZA! Come risultato di una costante innovazione, il robusto e universale trascinatore automatico per tubi rivestimenti progettato e brevettato da SIP&T può essere facilmente montato su tutte le perforatrici e non necessita di ulteriori regolazioni. Lo strumento non solo garantisce una condizione di lavoro sicura, ma garantisce un enorme risparmio di tempo durante la perforazione di pali rivestiti. È facile da usare perché il funzionamento è completamente meccanico; il trascinatore automatico verrà bloccato alla colonna rivestimento ogni volta che i tubi verranno collocati all’interno o all’esterno del palo trivellato. In tal modo viene rispettato l’imperativo “sicurezza prima di tutto”. Inoltre, si escludono danni ai tubi evitando tempi di fermo e risparmiando sui costi di riparazione.

La sua convenienza di prezzo, personalizzazione, uso agevole e intuitivo, facilità di manutenzione, unitamente a un sistema di emergenza, garantiscono un ritorno sull’investimento molto elevato.

56 ONSITEUNDERGROUND - september 2021

A Must-Have The connection system described represents an innovation in the cased piling construction. It is widely used in job sites all over the world, its feedback is extremely positive and we can state that nowadays it is recognized as a must-have tool. The application can make a significant contribution to improving safety in special deep foundations and, above all, in drilled piles. This particular locking system increases productivity as the various elements of the casing column can be assembled and disassembled faster than mechanic standard operations.

Furthermore, in presence of very long casings sections, the automatic driver is the main faster solution (the connection of long elements is not possible with the use of a simple ladder, a wheel loader or a harness). Lastly, the cost savings are evident, the personnel that can be used elsewhere on the site. The remote and management control is a great example of technical innovation that increases safety and productivity in special foundations.

■

NEWS BAUER SPEZIALTIEFBAU GMBH

Electricity from hydropower Bauer Engineering India Private Limited, a subsidiary of Bauer Spezialtiefbau GmbH, was tasked by Jaiprakash Associates Limited with execution of specialist foundation engineering and geotechnical work for the Teesta VI Hydro Electric project. The project developer is M/s. Lanco Teesta Hydro Power Limited, a wholly-owned subsidiary of the National Hydro Power Corporation of India. The project will be realized in the town of Singtam on the Teesta River. This river, which is more than 300 km long, rises from the Pahunri Glacier at an altitude of more than 7,000 m in the eastern Himalayas before flowing through the Indian states of Sikkim and West Bengal until it joins the Jamuna River at Fulchhari in Bangladesh.

Scope of works executed by BAUER Engineering India Private Limited include construction of an anchored pile wall, consisting of around 10,000 running meters of piles with a diameter of 800 mm, as well as around 60,000 running meters of anchors. The anchored pile wall will enable a 40 m deep excavation for the intake structure on the right bank. Along the upstream cofferdam 4.700 m² of grout curtain will be constructed using the jet grouting technique. In two individual stages on the upstream side of the barrage 4,600 m² of diaphragm wall will be built, using a trench cutter through the bouldary alluvium after pre-treatment. “Due to the special location of the Teesta River, it is proving challenging to both harness hydropower and also protect local residents against flooding,” says Harish Agarwal, Senior Vice President of Jaiprakash Associates Limited. Another challenge poses the limited space on site due to the relatively narrow valley and steep slopes as well as working in close proximity to an existing barrage. Construction works also will be executed through substantial bouldary strata and under erratic flooding pattern in the river. The work executed by Bauer started in April this year and is expected to be completed by fall 2024.

NOLEGGIO VENDITA ASSISTENZA NOLEGGIO VENDITA RIPARAZIONE DI GRU CINGOLATE ASSISTENZA GRU CINGOLATE RIPARAZIONE DI CINGOLATE ATTREZZATURE PERGRU FONDAZIONI SPECIALI GRU CINGOLATE Disponiamo di un parco macchine usato sicuro e garantito disponibile alla vendita e al noleggio.

ATTREZZATURE PER FONDAZIONI SPECIALI Disponiamo di un parco macchine usato sicuro e garantito disponibile alla vendita e al noleggio.

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COMPONENTS MP Filtri

ESD in hydraulic filters The study covered by this article stems from the need to understand and solve the problem of electrostatic discharges within hydraulic filters, resulting from the accumulation of electrical charge caused by the passage of oil inside them

by Emanuele Villa and Alessandro Negri

T

here are several problems of an electrostatic nature that arise in systems and industrial environments: in machinery and on floors, but also in the air and on persons. In the system under examination these phenomena can damage the filter elements, the oils or other components of the circuits, as well as cause fire hazards if you are

58 ONSITEUNDERGROUND - september 2021

in environments where flammable materials are present. This paper presents the results of an experimental study This paper presents the results of an experimental study in order to understand the physical phenomena that intervene in the observed processes and, where possible, to generate a qualitative comparison between empirical and modelling results.

Electrostatic theory The accumulation of charge on the filters occurs due to triboelectric effects, which take place when two bodies with different electronegativity come into contact (or are in friction).

The term “electronegativity” refers to the intensity of the attraction of a nucleus on the surrounding electrons.

For composite materials, this will depend on the electronegativity

Lower

Glass Syntetic ester oil ELECTRONEGATIVITY

Cellulose

RELATIVE SIGN AS A RESULT OF TRIBOLELECTRIC EFFECTS

Mineral oil Higher

FIG. 1 - Triboelectric scale for material of interest FIG. 3 = Electrostatic double layer (da STLE annual meeting 2016, W. Needleman)

FIG. 2 - Triboelectric effect by contact

of their constituent elements. The Fig. 1 shows the triboelectric scale (which provides information on the relative electronegativity) for the materials under examination: cellulose, glass, oils (similar to hydrocarbon derivatives). In the triboelectric effect, the body with greater electronegativity snatches electrons from the other, generating an accumulation of net negative charge on itself, charging the other by the same amount, but with opposite sign. In liquid-solid systems, contact is sufficient to generate this type of effect (Fig. 2). At the microscopic level, a double layer, is formed, consisting of an accumulation of surface charges (Helmholtz layer) on the filter material and a diffuse layer in the oil volume, whose charge distribution is exponential (Fig. 3). If the fluid is moving at a certain flow rate (Fig. 4), the flow carries away the charges in the liquid and causes an accumulation of net charge in the system, which gives rise to high potentials (up to tens of kV). The dissipation of the charge can occur through conduction or electrostatic discharge processes. The former are various, but it is useful to focus on the main dissipation mechanism in fluids: charge relaxation, represented in Fig. 5.

This occurs when the pipes or tanks in which the liquid passes or is contained are conductive (and connected to earth); through convective motions, attracted by the zero earth potential, the charged particles tend to approach the walls, where they release the accumulated charge. In solid insulating components such as plastics, however, only conduction currents are generated which, by dissipating the charge, prevent the accumulation of potential from diverging. Rather, the voltage is expected to reach a maximum value when the accumulated charge eaquals that dissipated. The charge accumulated in the system, in addition to being dissipated by conduction, sometimes gives rise to discharge phenomena. An electrostatic discharge is the passage of electrons through an insulating medium, the result of which is to bridge the potential difference between two areas of a body or between two distinct bodies,

FIG. 4 - Formation of net charge accumulation (from STLE Annual Meeting 2016, W. Needleman) TUBING

OIL

relaxation

TUBING

FIG. 5 - Charge relaxation in the pipes

generating an instantaneous current of very high intensity.

This is a process that gives rise to an emission of light due to the ionization of the molecules of the passing medium, which are sometimes damaged. This process takes place in situations where the electric field exceeds the dielectric strength (expressed in kV/mm) of the material (this system can be assimilated to a capacitor whose plate reaches its maximum capacity).

Experimental tests The experimental apparatus used consists of a test bench containing a hydraulic circuit in which a filter is inserted that can retain the solid contaminant and prevent this from damaging the machinery or the oil itself. The main components of a filter are head, filter element and container.

The filter elements used in this study are composed of a filter body, formed by the pleating of one or more layers (called media), which surround a perforated metal tube (spiral tube) and are glued together with two components called the base and the bead core. In Fig. 6 you can see the exploded view of a filter. The three aspects presented previously were investigated during the tests: accumulation of electric charge, conduction phenomena, electrostatic september 2021 - ONSITEUNDERGROUND 59

COMPONENTS 1. Head 2. Bead cores 3. Spiral tube 4. Filter body 5. Base 6. Container

FIG. 6 - Exploded view of a filter

discharges. The first occurs in the dielectrics present in the system: filter materials, oil, insulating pipes. As already mentioned, the origin lies in the triboelectric phenomena, which occur following the passage of the oil through the very fine pores (of the order of ten microns in diameter) of the insulating filter materials, namely cellulose or fibreglass.

Effects of discharges Discharge phenomena are difficult to investigate when they occur, due to the short duration and variability. It is easier to observe the effects on the bodies crossed: filter and oil. For the second, it appears difficult to identify and analyse the damaged molecules, analyses were carried out on the filter elements, which can be removed from the circuit and analysed in detail after use. In particular, it was considered interesting to analyse the effects of electrostatic discharges on standard elements subjected to a 30-minute test at a range at which discharges

Voltmeter that measures the filter potential 60 ONSITEUNDERGROUND - september 2021

are frequent and intense. The discharges occur inside different components of the filter: in the bead core, in the base and through the cellulose of the filter layer.

Significant damage to the filter material has been observed on the cellulose elements, both with the naked eye and using an optical microscope (Fig. 7), while the plastic components show no major damage except in the intersection between the spiral tube and the metal head. Therefore, it is assumed that the discharges occur between the filter body and the internal support metal tube, from which the electric charge then passes to the metal head through a further discharge.

As for the glass fibre filters, significant damage is observed only at the level of the bead and of the glue that joins it to the rest of the filter. The burns are visible on the surface and also extend inside the material (Fig. 8), compromising its mechanical strength. Finding that the fracture line follows the lines of damage caused by discharges (discharges that

A charge collector integrated into the circuit

FIG. 7 – Image of a cellulose septum damaged by the discharge and microscopic detail of the affected area

FIG. 9 - Images of the epoxy network at various magnifications

Solutions A solution has been found to the problem of the accumulation

of charges in the filters: a sort of electrical circuit must be created inside the filters themselves, obtained by replacing some insulating components with similar conductive versions, so that the charges on the septum are free to move towards the head and be dissipated to the earth. We will define the filters thus composed as “dissipative”, as they do not avoid the occurrence of triboelectric effects but are able to dissipate the charge that accumulates, as can be seen from Graphs 1 and 2. The values for the dissipative elements are represented in blue, those not in red. Note how, under standard working conditions, the potential goes from tens of kV to zero, showing the effectiveness of our dissipative filters.

For the glass fibre models the currents (Graph 3) have higher values than those in cellulose, but for both the order of magnitude is μA. There is an improvement in using the dissipative elements, despite which, however, no net charge is observed in the oil. The triboelectric effects therefore appear to be minor using dissipative elements, but the oil charge effect due to the passage in the filter materials is not avoided. The trend of the measured current appears to be, similar to the potential, a rapid but not exponential growth. However, there is no damping of current growth at high flow rates, so that the (asymptotic) saturation trend observed for voltage is not repeated. It is believed that this

Potential (glass)

Potential (cellulose)

FIG. 8 - Detail of the bead core of a glass filter damaged by drains

damage the filter material do not occur, also because the glass fibre has a dielectric strength of about 200 kV/mm, much higher than those reached in the system). In addition, minor damage can be seen on the epoxy resin coating of the metal mesh, an element present in the body to hold the different layers together (Fig. 9). The hypothesis, in this case, is that the charge accumulated on the filtering material is collected by the epoxy network, in which a conduction current passes through the coating of epoxy resin (insulator) which causes damage to it. From the network, the charges are then dissipated reaching the metal head through electrostatic discharges. In fact, discharge signs can be observed in the glue that follow the profile of the network embedded in it.

Standard filter

Dissipative filter

Dissipative filter

Potential (kV)

Potential (kV)

Standard filter

Flow rate (l/min) Graph 1

Flow rate (l/min) Graph 2 september 2021 - ONSITEUNDERGROUND 61

COMPONENTS

Internal view of the R&D Laboratory of MP Filtri

Current (cellulose)

Current (nA)

Current (nA)

Current (glass fibre)

Standard filter

Flow rate (l/min)

Standard filter Dissipative filter

Flow rate (l/min)

Graph 3

Graph 4

does not happen since no phenomenon similar to the electrostatic discharge in the filters takes place in the oil, responsible for limiting the growth of the potential. However, there may

also be a limit for oil if the maximum ionisation of the molecules is reached.

For such analyses it will be necessary in the future to continue the tests on another experimental apparatus.

ITALIAN ABSTRACT

ESD NEI FILTRI OLEODINAMICI Lo studio oggetto di quest’articolo nasce dall’esigenza di comprendere e risolvere il problema delle scariche elettrostatiche all’interno di filtri oleodinamici, conseguente all’accumulo della carica elettrica causato dal passaggio dell’olio al loro interno. La soluzione? Il problema originario delle scariche elettrostatiche nei filtri viene evitato sostituendo alcune componenti isolanti con equivalenti conduttivi, che creano un circuito elettrico all’interno degli elementi filtranti, così che la carica elettrica generata dagli effetti triboelettrici possa dissiparsi passando per la testata metallica, collegata a terra.

62 ONSITEUNDERGROUND - september 2021

Conclusions The original problem of electrostatic discharges in the filter is avoided by replacing some insulating components with conductive equivalents. Create an electric circuit inside the filter elements, so that the electric charge generated by the triboelectric effects can dissipate passing through the metal head, connected to earth. The accumulation of charge in the oil cannot be avoided only by making the filters dissipative; these elements ensure the dissipation of the charge that accumulates on the filter, for which different countermeasures will have to be adopted. The built-in charge collector or another dissipater, if inserted in the pipes or in the tank, could be effective but not decisive. ■

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