WT0710

September 2007 Vol 1 Issue 1

The magazine for the tunnelling professional

September 2007 Vol 1 Issue 1

The magazine for the tunnelling professionalThe magazine for the tunnelling professionalThe magazine for the tunnelling professionalThe magazine for the tunnelling professionalThe magazine for the tunnelling professional

www.world-tunnelling.com

Mapping the Guadarrama Tunnels

Focus on Spain

Methods and trendsScaling

Building with recycled muck‘Green’ concrete

October 2007 Vol 1 Issue 2September 2007 Vol 1 Issue 1October 2007 Vol 1 Issue 2September 2007 Vol 1 Issue 1

CovIWT0710.indd 1 11/10/07 10:41:59

Earth Pressure BalanceSlurry Pressure BalanceHard RockPipe - JackingRolling Stock

BREAKTHROUGHSOLUTIONS

Lovat.indd 1 24/8/07 10:09:04

Making green happenTUNNELLING is as environmentally sustainable

as we choose to make it. Take a look at the recently-inaugurated Lötschberg Tunnel in

Switzerland – at the intermediate point of Mitholz, a huge effort on sustainable practices materialised. The result was the production of recycled aggregates from tunnel spoil to make economical and sustainable, high-quality concrete and shotcrete.

Over 800,000 m3 of concrete was produced from of concrete was produced from tunnel excavation tunnel excavation

material. Indeed, so material. Indeed, so successful was the successful was the operation that the operation that the entire site became entire site became self-suffi cient in self-suffi cient in aggregate production. aggregate production.

What is interesting is What is interesting is that everything was done that everything was done on site. No sooner had on site. No sooner had

the dust settled the dust settled from drilling from drilling and blasting and blasting then the then the whole whole

process of grading, crushing, production and quality testing began in earnest.

An aerial view of the site shows there was ample space for material processing – something that might not have been possible with an urban tunnel. Even so, at Lötschberg, contractor Satco Consortium and concrete-plant operator Mobilbaustoffe AG created a custom-built, concrete-production plant in an underground cavern. Clearly, this success story should be of interest not only to detractors who see large-bore tunnelling as irreconcilably non-sustainable, but also to contractors, consultants and clients.

At Lötschberg, it helped to have a client and contractor who appreciated sustainability issues, making the project the success it is. So, those, hopefully few, doubters who are still uncertain as to what large-bore tunnelling can achieve should read Herr Weiss’ abridged paper on pp 29-32. It makes interesting reading.

George Demetri, Editor

WEB ADDRESS www.world-tunnelling.com

Regulars1 Comment

3-8 Global news A round-up of the latest news and technology

9 Events

33 InnovationThe latest equipment releases and upgrades

Atlas Copco Rock Drills www.atlascopco.com/rock Atlas Copco Rock Drills www.atlascopco.com/rock Atlas Copco Rock Drills

7Atlas Copco Rock Drills

7Atlas Copco Rock Drills

Cifa www.cifa.com 9Continental Conveyors.co.uk www.continental-conveyor.co.uk Continental Conveyors.co.uk www.continental-conveyor.co.uk Continental Conveyors.co.uk

10Continental Conveyors.co.uk

10Continental Conveyors.co.uk

Equipos Mineros www.equiposmineros.com Equipos Mineros www.equiposmineros.com Equipos Mineros

11Equipos Mineros

11Equipos Mineros

Gemmo www.gemmogroup.it 3Geokon www.geokon.com 8Häny www.haeny.com Hänywww.haeny.com Häny

13Herrenknecht www.herrenknecht.com 2Jennmar www.jennmar.com 26Lovat www.lovat.com Cov IIMaschinen und Stahlbau Dresden www.msd-dresden.de 22Messe Berlin www.innotrans.com 15Meyco Equipment www.ugc.basf.com Meyco Equipment www.ugc.basf.com Meyco Equipment

19,21,23Meyco Equipment

19,21,23Meyco Equipment

Molenaar www.molenaar-beton.nl 27Putzmeister www.putzmeister.es/sprayedconcrete 31Robbins www.TheRobbinsCompany.com 35RocTest www.roctest.com 8Sandvik www.sandvik.com 5Shotcrete Technologies www.shotcretetechnologies.com Shotcrete Technologieswww.shotcretetechnologies.com Shotcrete Technologies

28Steam Engineering www.steamengineering.ca Steam Engineering www.steamengineering.ca Steam Engineering

30Steam Engineering

30Steam Engineering

VMT www.vmt-gmbh.de 4Washington Suburban Sanitary Commission www.wsscwater.com 14Washington Suburban Sanitary Commission

14Washington Suburban Sanitary Commission

Wirth www.wirth-europe.com 24Wyo-Ben www.wyoben.com Wyo-Ben www.wyoben.com Wyo-Ben

12Wyo-Ben

12Wyo-Ben

advertisersFRONT COVER

Four double-shield TBMs were used to bore the twin-tube, 28.3 km-long Guadarrama railway tunnel in Spain. Pictured is the

9.51 m-diameter Herrenknecht machinewww.herrenknecht.de

1COMMENT

[email protected] (Arch) BA(Hons), DipBldgCons (RICS)

Production [email protected] [email protected]@mining-journal.comAdvertising [email protected]

Advertising [email protected]+44 (0)20 7216 6086Advertising sales [email protected]+44 (0)20 7216 6053

ISSN 0026-5225World Tunnelling is published ten times annually by Mining Communications Ltd, Albert House, 1 Singer Street, London, EC2A 4BQ, UK© Mining Communications Ltd 2007A member of BPA WorldwideA member of the Periodical Publishers Association

CONTENTS

contacts

October 2007

20

11-15 Spain1: Continental Conveyor’s projects2: Mapping the Guadarrama Tunnels

16-17 SwedenMalmö’s Citytunnel is under way

18-19 India100 km of tunnels bring water to drought-ridden Andhra Pradesh

20 Sprayed concretePutzmeister keeps costs down for Austrian power station project

21-23 SandvikDrill and blast takes over from TBMs in Stage 3 of Himalayan scheme

25-27 ScalingOutlining the main methods of scaling, trends and today’s rigs

29-32 Concrete & shotcreteRecycled muck can produce green and economical building material

Features

01WT0710.indd 1 11/10/07 13:09:39

h e r r e n k n e c h t A G | u t i l i t y t u n n e l l i n G | t r A f f i c t u n n e l l i n G s w e d e n

Anzeige_englisch_Malmö/schweden_»world tunnelling«_et: 10.07_du: 25.9.07_200x275mm_4c_260907oc_fassung 02

PROJECT DATA

S-340, S-3412x EPB ShieldDiameter: 8,890mmDriving power: 2,400kWTunnel lengths:1x 4,623m, 1x 4,592mGeology: limestone

CONTRACTOR

MCG Malmö Citytunnel Group: Bilfinger Berger AG, Per Aarsleff A/S, E. Pihl & Søn A.S.

M A l M Ö | s w e d e n5

0.0

7 e

MAlMÖ: direct cOnnectiOn tO the Öresund.

In order to speed up the train traffic between Denmark and Sweden, the Malmö City Tun-nel is being built. Together with a new aboveground stretch, it provides a direct connection between the Swedish city’s main station and the Öresund Bridge.

Two identical EPB Shields from Herrenknecht are excavating two tunnels with a length of 4,623 and 4,592, respectively. The two machines each have a diameter of 8.89 meters and a driving power of 2,400 kilowatts. Enough power to cut through a layer of quartzous limestone up to a depth of 25 meters – and that at a remarkable speed. Thanks to top daily per formances of more than 30 meters, »Anna« (S-340) already completed its first section of a length of 2.7 kilometers after nine months on 21 August 2007. And its sister machine »Katrin« is only 150 meters away from its stage target. With continuously good tunnelling performances, the EPB Shields will reach the main station in summer and fall of 2008, respectively. This means that the City Tunnel can be opened on schedule in 2011.

Herrenknecht AGD-77963 SchwanauPhone + 49 7824 302-0 Fax + 49 7824 [email protected]

www.herrenknecht.com

158_eAz_Malmoe_WorldTunn_200x275_02_bp.indd 1 26.09.2007 11:58:14 Uhr

Robbins TBM will kick off Ceneri tunnel buildSwitzerland

�NEWS

SEE US AT SAIE - ITALYSEE US AT SAIE - ITALY24 - 28 OCTOBER 2007

Pav. 30 Stand A 25

TBM manufacturer Robbins has announced that a refurbished main-beam TBM will be the first of its machines to bore into the Ceneri Base Tunnel in Switzerland – one of the larger European tunnel projects in recent times. The 9.7 m-diameter TBM will be used to excavate a 2.4 m-long adit tunnel.

The announcement follows the recent signing of a contract between Robbins and Consorzio Monte Ceneri (CMC) JV, a consortium of CSC, Lugano, Frutiger SA, Thun, Rothpletz, Lienhard+Cie and Aarau.

Following its complete refurbishment in Milan, Italy, which will include increasing the diameter of the cutterhead from 7.6 m to 9.7 m, the TBM will be delivered to the Swiss job site where it will be the first on the

AlpTransit project to use larger diameter, 19 in cutters.

Previously, the machine was used successfully on the main headrace tunnel of the Kárahnjúkar Hydropower Project in Iceland.

Located in Switzerland’s Canton Ticino region, the Ceneri tunnel will form part of owner AlpTransit’s ambitious project to provide more efficient rail-freight routes via base tunnels through the Gotthard and Ceneri mountain ranges.

The project will comprise twin 15.4 km-long, north-south rail tunnels, so freight trains will need to only undergo minimal climbs, compared to the more usual long, steep gradients that characterise the Alps. It will also mean shorter passenger journey times between Zurich and Milan, while some routes, such as Lugano to

Bellinzona, will have their journey times slashed in half when the tunnel is fully operational.

Located at Sigirino, the adit tunnel junction will lie roughly halfway between the main rail tunnels. The geology in the area comprises schist, Swiss molasse and Ceneri orthogneiss with a UCS of 30-130 MPa (4,300-18,800 psi). TBM boring is expected to be good, with no squeezing ground or large water inflows anticipated.

New probe drills, being designed in Robbins’ US locations, will be used to verify ground conditions ahead of the TBM. Temporary tunnel supports, including rock bolts, ring beams and shotcrete will be used, depending on the geology. Excavated material will be temporarily stored at a lot on site for later preparation as rock aggregate for concrete.

Using the latest disc-cutter design, the Robbins machine will bore through geology similar to that found in the Gotthard Base Tunnel, which used 17 in back-loading disc cutters. Larger diameter,19 in back-loading disc cutters, pioneered at the Kárahnjúkar Hydroelectric Project, offer a higher cutter load and longer cutter life than the 17 in design, resulting in fewer cutter changes.

Stockholm to stage tunnel safety symposium 2008

Italy

SToCkholM, Sweden, will be the next venue for the International Symposium on Tunnel Safety and Security (ISTSS) on March 12-14, 2008. The venue will be Foresta, situated at the entrance to the island of lidingö, near the capital.

This third gathering reflects the continuing support for the event and growing, global concerns for improving tunnel safety and security.

The symposium began in Sweden in 2003 as The Interna-tional Symposium on Catastrophic Tunnel Fires and attracted over

200 delegates, prompting a broadening of ISTSS’ scope.

keynote papers will cover active and passive fire protection, firefighting, security, emerging research and case studies.

Deadlines for submission of paper abstracts lapsed on 1 June and those who have submitted them will be notified of accept-ance by November 1. Full papers must be received by January 1, 2008. English will be the official language of the conference.

Details: see Events, p9, or call +46 10 516 5219.

NEWS�

October 2007

03-04,06-09WT0710.indd 3 10/10/07 16:55:42

Herrenknecht invests $8m in its fi rst assembly plant in India

India

NEWS

Colle Urania tunnel begins

Italy

ACKNOWLEDGING India as a key future market for mechanised tunnelling, Germany-based TBM manufacturer Herrenknecht is investing US$8.15 million in an assembly plant in Chennai on the sub-continent’s southeast coast.

Herrenknecht India Pvt Ltd will be operational in spring 2008. The modern plant will be used for the assembly of tunnelling machines, as well as producing components and tools. It will feature a 3,000 m2

assembly hall, a production plant for cutter discs for excavating hard rock, and a storage warehouse for spare parts, all covering a total area of 40,000 m2.

India has a massive requirement for new tunnels and pipelines, and Herrenknecht is involved in a variety of schemes there.

For example, this winter, a 7.96 m-diameter Herrenknecht

double-shield TBM will begin excavating a 18.8 km-long water-supply tunnel near Hyderabad (Southern India). Herrenknecht is also supplying a lining-segment production facility (concrete

segments for lining the tunnel), as well as technical back-up.

This year has seen the company receive orders for eight EPB shields to bore 18 km of tunnel for New Delhi’s subway extension.

PROCEEDINGS are being initiated by the European Commission against Greece and Luxembourg for failing to carry out EU direct-ives on minimum safety require-ments in tunnels. The two member states will now have to go before the European Court of Justice.

Directive 2004/54 stipulates the

minimum safety requirements applicable to all tunnels of over 500 m on the trans-European road network. The directive is the distillation of lessons learnt from recent tragedies in Alpine tunnels.

EU members had until April 30, 2006 to transpose the directive into their national legislature, but

Greece and Luxembourg did not implement any measures.

Typical minimum requirements include escape routes, emergency exits, illumination, ventilation, monitoring and communication systems. Any necessary refurbish-ments are required to be completed by April 30, 2014.

CONSTRUCTION has started on the tunnel, part of the Ruzzo water tunnel expansion in Teramo, Italy. The joint venture responsible for the works – Società Italiana per Condotte d’Acqua and Orion – is using a Lovat RMP167SE Series 21701 TBM for the excavation.

Used successfully on previous projects in Tuscany, the TBM has been refurbished prior to starting work on this, its latest assignment. But, it will be tough work, as the site will be working three, eight-hour shifts, fi ve days a week.

With only a few weeks having elapsed since launch, production rates have averaged over 1 m/hr (135 m/week) with higher rates anticipated once all tunnel logistic systems are installed.

Geology along the 2 km-long tunnel alignment is character-ised by marl and argillite. Excavation is expected to take less than six months.

Breakthrough of the 6.45 m-diameter Herrenknecht EPB-Shield S-197, which was used at the New Delhi subway system

Greece and Luxembourg in the dockEU

NEWS4444444

October 2007

www.vmt-gmbh.de

03-04,06-09WT0710.indd 4 11/10/07 09:54:05

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Untitled-4 1 8.10.2007 15:05:48

NEWS

➜Jacobs’ acquisitionTunnel engineer Jacob Associates recently acquired selected assets and staff of geotechnical and rail tunnel specialist Milbor-Pita & Ass

IN BRIEF

�

October 2007

�NEWS

AustriA’s second-largest construction company, Alpine, has been awarded the $123 million contract to build the second Pfänder Tunnel tube in Austria by Asfinag.

As the lowest bidder, Alpine says it won the contract due to its “competence in tunnel construc-tion and optimum cost structure”.

Alpine’s bid team, which included Beton- und Monierbau, pitched against four other bidders.

The Pfänder contract is notable in that, for the first time, bidders were able to choose between TBM-boring or drill-and-blast to construct the western tube of the 6.5 km-long motorway tunnel. Alpine opted for TBM.

Construction is due to begin in October and is scheduled for

completion by summer 2012. Alpine has been involved in several high-profile projects in recent years, including the Gothard Base

Tunnel, Katschberg Tunnel and Athens Metro. Last year, Spanish construction group FCC acquired a majority stake in Alpine.

US-bASed Robbins recently completed the assembly of a 6.7 m-diameter main-bean TbM, which will be used to bore two sections of rail tunnel totalling 12.5 km on MTA’s east Side Access project in New York.

The project aims to ease commuter travel between Queens and Manhattan.

Comprising twin rail lines, crossing the east River through an existing submersed tube, the TbM will be used for the westbound Manhattan approach tunnel.

A further hard-rock TbM will be used to bore the eastbound tunnel.

Partial assembly of the Robbins TbM will take place at the bottom of a 23 m-deep portal shaft, located in the city centre, and it will be completed in an underground chamber on the Manhattan side after being transported about 1.8 km through the submersible tube. Having bored an initial heading, the TbM will be demobilised and retracted to excavate a second heading up to Grand Central Station.

Transportation will be easier through the varying tunnel cross-sections and smaller-diameter submersible tube due to the TbM’s expandable and retractable components, which allow it to adapt from 6.136 m to 6.906 m in diameter.

The tunnel alignment primarily crosses Manhattan schist with gneiss, from 80-200 MPa (11,600-29,000 psi) UCS, while support will vary between in-situ concrete lining, steel ribs, rock bolts and wire mesh.

Muck will be removed by continuous conveyors that transport the spoil to a storage site 366 m away. One of these will be 37 m long and is being designed as an enclosed box truss because it has to cross a major boulevard at 6 m above road level.

Completion of the tunnels is scheduled to take 18 months, while the completed east Side Access line should be up and running by 2013.

doing the devil’s work

US

COnSTruCTiOn has begun of a uS$272 million, twin-bore, 1.3 km tunnel through the mountain at Devil’s Slide, California.

When complete, it will provide an alternative route to the notorious, winding stretch of highway that hugs the mountainside above California’s Pacific coast, which has seen landslides, rockslides and countless closures since its 1937 opening.

Piercing through San Pedro mountain, the Devil’s Slide Tunnel will link Montara and Pacifica, as well as other coastal communities stretching along San Mateo county. When complete, it will be California’s longest highway tunnel and provide a safer, more permanent route for drivers.

Each bore will have a single traffic lane, a cycle lane, emergency walkways and jet-fan ventilation.

Although preliminary work on the project began in 2005, official digging only began on September 17 when 145 people attended a ceremony at the south portal.

Each tube will be 9.15 m wide and 6.70 m high. nATM will be the method of excavation, with Terex diggers and earth-moving equipment slowly progressing up the 2% gradient.

it is anticipated that a selection of granite, sandstone, shale and clay will be encountered along the tunnel alignment.

Two ATM 120 t roadheaders, manufactured by Sandvik Group’s Austrian subsidiary, Voest Alpine, will carry out much of the work. Contractor Kiewit Pacific will use two of the ATM 105 roadheaders, one for each tube. Where necessary, explosives will be used to displace hard rock.

Alpine scoops Pfänder contractAustria

The Gothard Base Tunnel at Faido, one of Alpine’s past projects

Manhattan transfer for retractable robbinsUS

�

Assembly of the 6.7 m-diameter Robbins TBM was completed on July 27

03-04,06-09WT0710.indd 6 10/10/07 16:56:23

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�NEWS

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NEWS�

Hindustan Construction Company (HCC) has won the US$180 million irrigation-tunnel work on the Pula Subbaiah Veli-gonda Project in Andhra Pradesh, India. HCC is lead partner (60% share) in a JV with Coastal Projects Pvt. The award was made by the Irrigation and CAD Department of the Andhra Pradesh government.

Envisaged in the contract are the investigation, design, execution and construction of an 18.8 km, 9.2 m (i.d.) tunnel that will form part of the water-conveyance system, linking the Srisailam Reservoir to Guntur-Kurnool road to join the Feeder canal. It is envisaged the project will take five years.

HCC is currently building the US$120 million, 11 km-long Banihal rail tunnel in Kashmir.

InnoTrans 2008, the Interna-tional Trade Fair for Transport Technology, which covers components, vehicles and systems, will be held in Berlin, Germany, on September 23-26, 2008. There will be a strong presence from the tunnelling industry.

For only the second time, a tunnel section will focus on construction products, materials, information and safety systems, R&D, and the full range of services for the tunnelling sector. Some of the market leaders in international tunnelling will also be present.

The section devoted to Tunnel Construction is organised in close co-operation with the German Research Association for Under-ground Transportation (STUVA), which enjoyed a successful debut at InnoTrans 2006.

‘Tunnel Construction’ is a platform that has been designed to foster business contacts between exhibitors and visitors engaged in tunnelling. It will be supplemented

by brief, compact discussion forums under the aegis of STUVA. Tunnelling participants will also benefit from interaction with other sectors that will be present, such as transport companies.

At InnoTrans, the International Tunnel Forum will be organised jointly by STUVA under the leader-ship of Prof Dr Alfred Haack and the International Tunnel Association (ITA).

Spread over two days, the compact, two-hour sessions will provide a discussion forum with leading experts on relevant tunnelling subjects.

The 2008 show looks set to be another success, given that more than three quarters of last year’s display area has already been booked. The trend for larger stands at InnoTrans also applies to the tunnelling sector. Located in Hall 5.2, it will be close to the railway infrastructure section which will be useful for visitors.

Further details are availabe at www.innotrans.com.

HCC awarded irrigation work

India

Innotrans 2008 shapes up for Berlin stage Germany

The Kirchenwald Tunnel, being built in the Swiss Alps

NEWS�

October 2007

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October 2007

2009

Nov 5-7: International Congress – Tunnels, Drivers of Change (AETOS) – Madrid, Spain. Details: Tel: +91 531 06 00. Fax: +91 531 05 41. E-mail: [email protected] 27-29: STUVA-TAGUNG’07 – Connections by Tunnel – Cologne, Germany. International conference on developments in underground construction.Organised by the German Research Association for Underground Transportation Facilities (STUVA). E-mail: [email protected]. Website: www.stuva.deNov 27-29: INTERtunnel 2007 – Pavilion 8 at Expocentr, Moscow. Technology and services for the construction and operation of tunnels and undergroundspaces in Russia. Details: Ulika Tosner, Mack Brooks Exhibitions. Tel: +44 (0) 1727 814 400. Fax: +44 (0) 1727 814 401. E-mail: [email protected] 11-15: CONEXPO-CONAGG 2008 – Las Vegas, US. North America’s largest major construction event with major international participation. Details: ShowManagement: Tel: +1 414-298-4144. E-mail: [email protected] 12-14: ISTSS 2008 – International Symposium on Catastrophic Tunnel Fires – 3rd International Symposium on Tunnel Safety and Security, Stockholm, Sweden Details: Margaret Simonson. Tel: +46 10 516 52 19. Website: www.sp.se/en/units/fi re/news/istss2008/sidor/default.aspx May 4-7: 13th Australian Tunnelling Conference, Melbourne. Organiser: Australian Tunnelling Society. Tel: (03) 9662 3166. Email: [email protected]: www.atstunnellingconference2008.com May 5-9: Samoter 2008 – Verona, Italy. Details: Verona Fiere, Viale dellavoro 8, 37135 Verona, Italy. Tel: +39 045 8298111. Fax: +39 0458298288. Website: www.samoter.itMay 20-22: Intertunnel 2008 – 8th International Tunnelling Exhibition – Turin, Italy. Details: [email protected] Website: www.intertunnel.comJun 7-11: North American Tunnelling (NAT) Conference – San Francisco, US. Advances in tunnel engineering. Website: www.smenet.org/meetings/nat/2008/callForPapers.cfmJun 23-25: 2nd Brazilian Congress of Tunnels and Underground Structures, Sao Paulo. Tel: +55 11 3871 3626. E-mail: [email protected] 17-18: IUT 2008 – 5th International Underground and Tunnel Fair. Website: www.iut.chSept 22-24: MINExpo International 2008 – Las Vegas, US. World’s largest exhibition of mining and associated equipment. Details: Tel: +1 630 434 7779. Fax: +1 630 4341216. E-mail: [email protected]. Website: www.minexpo.comSept 22-27: World Tunnel Congress and 34th ITA General Assembly – New Delhi, India. Tel: +91-11-2615984/26116567. E-mail: [email protected]. Website: www.cbip.orgSept 23-28: InnoTrans 2008 International Trade Fair for Transport Technology – Berlin, Includes International Tunnel Forum organised by ITA and STUVA. Tel: +49 (0)30 3038-2036. Fax: +49 (0)30 3038-2190. Website: www.innotrans-berlin.ru/english. E-Mail: [email protected] 22-24: Underground Infrastructure of Urban Areas 2008 – Organised by Wroclaw University of Technology, Poland. Details: [email protected] 23-28: World Tunnel Congress and 35th ITA General Assembly – Budapest, Hungary. Preliminary advice only. Website: www.ITA-Aites.orgJun 14-17: Rapid Excavation and Tunnelling Conference RETC 2009 – Las Vegas, Nevada, US. Details: Tel: +1 303 973 9550; Fax: +1 303 973 3845.E-mail: [email protected] Website: www.smenet.org available to visitors. Events highlighted in red are those where World Tunnelling will be available to visitors

03-04,06-09WT0710.indd 9 10/10/07 16:57:38

A World Leader in Conveyors and Conveyor Technology

Continental Conveyor LimitedWest Quay Road, Sunderland Enterprise Park, Sunderland, SR5 2TD. UK

Tel: +44 (0)191 516 5353 Fax: +44 (0)191 516 5399 E-mail: [email protected]

A CONTINENTAL GLOBAL GROUP COMPANY

October 2007

11PROJECT: Spain

Delivering the goodsContinental Conveyor was recently involved in two Spanish projects, with different operational criteriaBEING aware of the major tunnelling

objectives designed to improve Spanish infrastructure led to new opportunities

for Continental Conveyor (CC). In addition to Line 9 of the Barcelona Metro and two tunnels for Barcelona Airport, its work has encompassed a more diffi cult project: the 28.4 km-long Guadarrama tunnel on Spain’s new north-south high-speed rail link.

But, diffi cult projects are CC’s speciality, says Paul Bancroft. “We have the edge when the tunnel profi le is diffi cult as it allows us to use our experience in underground construction.”

Originally based in mining, CC sought new horizons when the sector began to slow down in the mid-1980s. In 1990-99, it completed major tunnelling projects in the US and Australia. But, its greatest success was in 2002 when it secured all three phases of the Channel Tunnel Rail Link.

GUADARRAMASpain’s topography, with internal and coastal rock masses in the north, northeast and south, has necessitated the construction of numerous base tunnels to speed up journey times between the interior and coastal regions. The Guadarrama Tunnel is on Spain’s Madrid-north and north-west high-speed line, about 70 km north of Madrid and near Segovia. CC supplied two conveyors of 13.4 km and 15 km long.

Begun in 2003, the 28.4 km-long tunnel comprises twin 8.5 m diameter tubes, about 30 m apart, each having a section of 52 m2. Split into north and south sections of roughly

equal length, the tunnels were bored using four double-shield TBMs – two boring from the north and two from the south – with both meeting at, or near, the mid-point. With excavation diameters of 9.5 m and a shield length of 15 m, the TBMs were equipped with 26.7 t capacity, 17 in disc cutters, which could be accessed from the machine chamber.

Boring through gneisses (62%), granitoides (26%), dykes (8%) and faults (4%), TBMs were chosen not only because they were faster, but also because the Guadarrama is in an environ-mental area, ruling out the use of explosives.

CC’s involvement was limited to the northern section of the Guadarrama contract, providing a conveyor in each tunnel. Bancroft claims the

installed one is probably the longest single-fl ight conveyor anywhere. Comprising 2x160 kW main drives and three separate boosters (each comprising two 160 kW main motors), the conveyor had a 900 mm-wide steel-mesh cored-rubber belt with a capacity of 1,150 t/hr.

Herrenknecht preferred a conveyor that was chain-hung from the roof, whereas a wall-mounted system was used in the Wirth tunnel. Both conveyors were operated on a 24-hour basis, but, as you might expect, some breakdowns occurred, requiring ongoing maintenance that was, as far as possible, carried out in parallel with TBM maintenance.

Monitoring the conveyor and maintenance was carried out by two of the client’s workforce, trained by CC to adjust and maintain the belt. This included inserting new lengths of belt as the bored length of tunnel increased; it also included vulcanisation of the newly-inserted belt loop; a process that can take up to eight hours. When this is necessary, the new storage loop, which can come in 300 m lengths and weigh up to 6-8 t a piece, is installed and inserted at the portal. Monitoring conveyor performance was achieved remotely.

However, as the TBM driver needs constant control and visibility of the muck-handling process, sophisticated control systems integrating TBM and conveyor are available. In this case, CC devised software that was customised for the project, which was completed in 2005.

BARCELONA METROPhase 1 of the UTE Line 9 contract, awarded in January 2002 and now complete, comprised a 10.9 m internal diameter, single-tube, 8.4 km-long, TBM-excavated tunnel. On a contract worth around US$2.8 million for CC, the fi rm supplied an 8.39 km-long conveyor, designed to negotiate curves as tight as 280 m in radius.

As the tunnel was completed in two phases,

the contract was in two parts. With the fi rst consignment delivery in July 2003, the 4.07 km-long, phase-one conveyor was 1,000 mm wide with a 1,120 kW rating. On phase two, the requirement was for a 8.39 km-long belt at 1,600 kW. In the event, this was achieved by using the belt from phase one and adding a 4.32 km extension.

With a 160 kW head drive at the portal and fi ve 160 kW boosters along its length, the 1 metre-wide, wall-mounted conveyor was adapted to go around corners. It was routed through the TBM back-up where a team of men inserted supporting brackets at roughly 2 m intervals into pre-formed holes in the tunnel segments.

Thanks to Paul Bancroft of CC

Schematic of booster confi guration

11WT0710.indd 11 10/10/07 16:04:32

The new, twin Guadarrama Tunnels cross the Central Range (Sistema Central) of the Iberian Peninsula, between Madrid and

Segovia, forming part of the new high-speed railway line in northwest Spain. They are 28.3 km long, with a maximum overburden of 900 m.

The tunnels have been constructed using four double-shield TBMs, all with an excavation diameter of 9.5 m. To predict ground conditions in detail ahead of the TBM face, a review of the geological features was carried out. This comprised detailed geological mapping, with a precise photo-geological study and systematic electrical resistivity tomography (ERT) profiles along the axis of both tunnels. Also, several geophysical investigation methods were applied to afford good knowledge of the rock mass.

In-situ geotechnical tests were also carried out, yielding ground-geomechanical parameters: Ë Surface tests, carried out from the South Portal, previous to the TBM; Ë Surface tests, carried out from the North Portal, previous to the TBM;

Ë La Umbría Fault, where various methods have been applied at the surface, in borehole, surface-to-borehole or borehole-to-borehole.

At the main faults, inclined boreholes were drilled to perform dilatometer and permeability

Mapping the Guadarrama TunnelsAdvanced geological mapping was used on the recently-completed tunnels. This paper (abridged), taken from the recent WTC in Prague, outlines the procedures

October 2007

12PROJECT: Spain

The tunnels have been excavated using four double-shield TBMs; all of them with an excavation diameterof 9,5m.

2 MAIN GEOLOGICAL FEATURES

The geological conditions consist of crystalline rocks,gneiss and granites crossed by several types of dykes.A main graben in the Lozoya valley where poor qual-ity sedimentary rocks from the Cretaceous, includingloose sands under water table, were crossed is themostproblematic section of both tunnels. Nevertheless sev-eral faults and dykes have also been detected in thesite characterization jobs, inside the crystalline bodieswith different mylonites and water conditions.In the Figure 2 a longitudinal geological section

of the tunnel is shown. It can be appreciated, the twomain faults encountered that have been intensivelyinvestigated in advance using geophysical methods.There two faults corresponds to Valparaiso and to

La Umbría fault areas.

3 METHODOLOGY USED FOR THEPREDITION OF GROUND CONDITIONSAHEAD THE TBM FACE

Since the beginning of the excavation, the majorimportance of having a prediction of the ground con-ditions ahead the TBM face has been demonstrated,in order to take the decision to advance in a single orin a double-shield way or if it is necessary to make aground improvement ahead the face of the tunnel.For this purspuse a review of the main geological

features has been done.This review has consisted of a detailed (1:1000

scaled) geological mapping with a precise photoge-ological study.

Figure 2. Geological profile of the tunnels of Guadarrama.

Following this geological mapping an intensivegeophysical survey of both tunnels was done. Thissurvey has consists in the following works:

– Geophysical methods applied from surface.– Geophysicalmethods applied between boreholes orbetween borehole and surface.

In Figure 3 it is shown a block-diagram showing therelationships between the different technologies used(Capote, 2005).As a prediction tool a systematic Electrical Resis-

tivity Tomography (ERT) profiling along the axis ofboth tunnels has been carried out.In the main faults and accidents further inclined

boreholes were drilled in order to perform dilatometerand permeability in situ tests, as well as to make somegeophysical logging.

Geological Supervisionof the tunnel face

Geological Mapping(1/2000 and1/5000)

Boreholes Fault zones La Umbria

Estimated GeologicalTunnel Profile

Definitive GeologicalTunnel Profile

Structural AnalysisMet. Rock→Sch.

Ing. Rock→Fabric.

Geophysical LoggingIn Situ Testinge

Further geophysicalprospection

FurtherIn Situ Tests

ProyectionsBoreholes

Fault traces

Geophysical MethodsERT between boreholes

Seismic TomographyOthers

Revision of the project Maps/Sections

Boreholes

Detailed GeologicalTunnel Profile

ContiniousERT

Figure 3. Methodologyused for the prediction of the groundconditions ahead the TBM face (modified from Capote,2005).

204

Geological profile of the tunnels

12-15WT0710.indd 12 10/10/07 17:48:16

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in-situ tests. With all this data, it was decided in advance whether the double shield would work in single or double mode. An expert system has been used to interpret the data coming from the TBM after crossing the expected faults, thereby providing feedback for the entire process.

GEOLOGICAL FEATURESThe geology comprises crystalline rock, gneiss and granite, crossed by several types of dykes. A main graben in the Lozoya Valley where poor-quality, sedimentary rocks from the Cretaceous was crossed – including loose sands beneath the water table – constitutes the most problematic section of both tunnels.

Nevertheless, several faults and dykes have also been detected in site-characterisation jobs inside the crystalline bodies with different mylonites and water conditions. The two main faults that were crossed have been intensively investigated in advance using geophysical methods.

THE PREDICTION OF GROUND CONDITIONS AHEAD OF TBM FACESince the beginning of the excavation, the importance of predicting ground conditions ahead of the TBM face was necessary in order to decide whether to use a single- or double-shield machine and whether it was necessary to make ground improvements ahead of the tunnel face.

Following detailed (1:1000 scale) geological mapping, an intensive, geophysical survey of both tunnels was undertaken, consisting of:ËGeophysical methods applied from the surface.ËGeophysical methods applied between boreholes, or between borehole and surface.

As a prediction tool, systematic electrical-resistivity tomography (ERT) profiling was carried out along the axis of both tunnels. In the main faults and unforeseen geological conditions,

inclined boreholes were drilled to carry out in-situ dilatometer and permeability tests, as well as undertaking geophysical logging. This method proved effective and very precise, down to an overburden of about 150 m. Special attention was paid to the La Umbría Fault, where several geophysical methods were applied. Here, most

Mapping the Guadarrama Tunnels

October 2007

13PROJECT: Spain

Ë

Definitive geologicaltunnel profile

Estimated geologicaltunnel profile

Detailed geologicaltunnel profile

Geophysical methodsERT between boreholes

Seismic tomography/others

ProjectionsBoreholes/Fault traces

Structural analysisMet. rock ]sch

Ing. rock ]fabric

Boreholes fault zonesLa Umbria

Geological mapping(1/2000 and 1/5000)

Revision of the projectMaps/sections

Boreholes

ContinuousERT

Geophysical loggingIn-situ testing

Further geophysicalprospecting

Further in-situ tests

Geological supervisionof the tunnel face

Flowchart for predicting ground conditions ahead of the TBM (Capote, 2005)

12-15WT0710.indd 13 10/10/07 16:13:37

of the geophysical and in-situ tests were used to predict the structural position of Cretaceous loose sands, as well as the position of the main gouge fault zones. Tectonised zones were found in the northern part of the valley.

ELECTRICAL RESISTIvITy TOMOGRAPHy (ERT)Electrical-resistivity tomography (ERT) for the detection of faults has been used before since faults usually give low values of resistivity due to the presence of clay minerals and a high water content. The method is based on measuring the potential difference between two electrodes and obtaining the resistance of the ground to current flow. After several trials, a unit electrode-spacing of 10 m was used for low overburden, obtaining a constant depth of investigation of about 60 m.

Two parallel profiles were taken along both axes of the tunnels. To define and classify the faults, a detailed interpretation process was used, comprising the following steps:Ë�The apparent resistivity pseudo-section

is measured.

Ë�Resistivity is calculated from resistance value.

Ë�An iterative inversion process is carried out, minimising error between the measure-ment and calculated values of resistivity. This is given by the value of RMS error expressed as a percentage.For the final interpreta-

tion, analysing the chargeability section has provided data for the prediction of water inflow into the tunnel. Since the

start of the excavation from the north portal, more than 11,980 ml of ERT profiles have been carried out, while the excavated length is 13,500 m for each tunnel (tunnels 3 and 4).

3D INTERPRETATION OF ERTIn the La Umbría fault, 4,600 m of ERT profiles from surfaces were undertaken, as well as five electrical-tomography borehole-borehole and six ERT borehole-surface profiles. This

allowed the creation of a complex, 3D interpretation of the fault.

SEISMIC CROSSHOLE TOMOGRAPHySeismic tomography is based on elastic wave propagation to arrive at a spatial distribution of

Equipment LogSchlumberger HALS-PEX-Laterolog-Plataform Express Logs HNGS – Espectometría Gamma Nuclear FMI-Fullbore Fm. Microimager DSI-Dipolo Shear Imager GR-Gamma RayMount Sopris Caliper Acoustic Televiewer Full wave sonic Temperature Gamma Ray Conductivity Resistivity SP

Geophysical logging used in boreholes

October 2007

14PROJECT: Spain

Ë

“Electrical sensitivity

tomography for the

detection of faults has been used before”

12-15WT0710.indd 14 10/10/07 16:13:38

velocities inside a volume of rock mass. Once data acquisition is complete, the velocities between all mesh nodes are calculated. In the La Umbria Fault, a seismic survey was carried out between boreholes, which considered:Ë�The distance between boreholes – the longer the distance, the lower

the accuracy.ËThe distance between geophones and shot points.ËAccuracy in determining the positions of transmitter and receptors.

IN-SITU TESTINGThe following techniques were used:ËGeophysical logging (see table).ËHidrofract tests.ËDilatometer tests.

These tests proved useful for the geotechnical classification of the site at the La Umbria fault, as well as for other tectonic features. The geo-physical logging and in-situ testing carried out inside the drilled boreholes has provided valuable information concerning:ËStructural data.Ë�Natural stress field (with a high ratio k0, between horizontal and

vertical stresses).Ë�Rock-mass deformability, especially in the Cretaceous sedimentary

rocks, including loose sands.

CONCLUSIONSThe geophysical surveys and in-situ tests have contributed to defining the geological and geomechanical profile of the Guadarrama tunnels. This method has provided advance knowledge of the construction difficulties that the four TBMs would face while excavating in the rock mass. The results of these measurements are as follows:Ë3,501 lm of seismic profiles.Ë24,870 lm of surface ERT.Ë�11,019 lm of geophysical

logging.Ë3,860 lm of VLF.

Ë5 ut ERT borehole-borehole.Ë6 ut ERT borehole-surfaceË18 ut seismic-tomography borehole-borehole.Ë25 ut dilatometric tests

In the gneiss and granites of the Guadarrama Tunnels, ERT has proven to be an efficient system for predicting faults and dykes ahead of the TBM. Using chargeability profiles has proved interesting for predicting water inflow conditions. Interpretation is very difficult when the strike of the resistivity anomaly is parallel to the axis of the tunnel.

Using the resistivity profile, it was decided in advance whether the TBM would operate in single- or double-shield mode. For an over-burden higher than 250 m, no geophysical survey was used as none of the tests carried out gave enough reliability and accuracy in interpretation.

At the Umbria Fault, electrical and seismic tomographies have contri-buted to defining the position of Cretaceous loose sands. In-situ tests also contributed, in conjunction with the geotechnical logging of drilled bore-holes and the last test for the mechanical characterisation of the rock mass.

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October 2007

15PROJECT: Spain

“Using the resistivity profile, it was decided in advance whether the TBM would

operate in single- or double-shield

mode”

12-15WT0710.indd 15 10/10/07 16:13:41

October 2007

16

Malmö central station is a terminal station and trains from the Öresund Crossing (between Copenhagen and

Malmö) travel round the south and east of Malmö and into the station. The Citytunnel will bring the link though Malmö with two suburban stations at Hyllie and Triangeln.

The official go ahead was not given until early 2005. This article marks the first of four break-throughs with the completion of the first 2.6 km tunnel drive to Triangeln station at the end of August 2007. The second tunnel breakthrough is planned for early October 2007 and the final two breakthroughs in the spring of 2008.

Nearly half of the tunnelling is now complete and is ahead of programme. However, the lime-stone will be more fractured in the latter stages of the two drives, so although the project team are hopeful of an early completion, the progress to the final breakthroughs is being planned conservatively.

GeoloGy and HydroGeoloGyThe natural geology along the route is generally moraine overlying limestone with some sediments of sand and gravel locally.

The limestone has three distinct layers. The upper layer, up to 8 m in thickness, is the Copen-hagen Limestone which is fractured and highly permeable. The middle layer, down to a depth of 50-60 m is the Bryozoan Limestone whose upper layers are fractured, but the main body of the limestone generally has a lower permeability. However, its permeability increases to the north of Triangeln station. The third layer is the Chalk.

There are two watertables, the upper varying between 1 and 7 m below the surface while the lower lying in the limestone at roughly sea level.

THe ProjecTThe Citytunnel is a 17 km-long new railway alignment and works are being constructed under around 30 contracts. Works are as follows:Ë�5 km of depressed route, at 4-7 m below

ground level from the existing Öresund link at Lemacken to north of Hylie station;

Ë�6 km of twin tunnel under Malmö;Ë�6 km of depressed route to connect the

Öresund link eastwards to Trelleborg, Ystad and Vintrie;

Ë�A sunken Hyllie station with four tracks and two island platforms;

Ë�An underground cavern station at Triangeln with a central platform; and

Ë�An underground station at Malmö Central with four tracks and two island platforms, with connections into the existing station.

Ë�Contract E101 – Malmö Central Station award-ed to the Swedish contractor NCC Construction Sverige AB (contract value US$182.77 million);

Ë�Contract E201 – Tunnels and Triangeln station awarded to The Malmö City Tunnel Group, a consortium of the German contractor Bilfinger Berger AG, and the Danish contractors Per Aarsleff A/S and E Pihl & Son A/S (contract value US$ 350.26 million).

The Swedish Prime Minister, Göran Persson, officially started the US$1.25 billion project on March 8 2005. Extensive site investigations and

environmental issues were discussed in the March 2004 issue of World Tunnelling.

Bored Tunnel WorksTunnel Boring MachinesThe Malmö City Tunnel Group (MCG) ordered two EPB TBMs from Herrenknecht in October 2005. The TBMs were manufactured at the firm’s works at Schwanau, in Germany, and were delivered to site in September and November 2006. The main details of the TBMs are given in the table (below).

Tunnel lininGsTunnels have an internal diameter of 7.9 m with a 1.8 m-wide lining, 350 mm-thick. The ring is made up of seven segments and a wedged key and has an EPDM gasket in the joints manufactured by Dätwyler, from Switzerland. The segments have rebar reinforcement and 1 kg of polypropylene fibres to improve their durability against fire. The segments are cast in a specially

Malmö’s excellent progressThe Citytunnel in Malmö, Sweden, is well under way and constitutes a complex array of tunnelling and associated works. Rodney Craig reports

Shield diameter 8.89 mShield length 9.5 mBackup length 130 mWeight of shield 700 tWeight of backup 550 tType of TBM EPBCutterhead power 2,400 kWCutterhead torque 11,785/12,627 kNmNumber of rams 14Total thrust 52,030 kNCutterhead speed Max 4.5 revs/minNumber of discs 55

TBM specifications

ProjecT: Sweden

The Herrenknecht TBMPhoto: Herrenknecht

Cut and cover adjacent to reception pit

16-17WT0710.indd 16 10/10/07 15:23:48

October 2007

17

Malmö’s excellent progressbuilt precasting yard on the site designed and manufactured by CBE Tunnels of France. The segments are pre-cured for three hours and then steam cured for seven and a half hours before demoulding. The daily production is ten rings.

Tunnel drivinGThe first TBM started on November 18, 2006 and completed the 2.7 km initial drive to Triangeln station on August 21 2007 at an overall average weekly rate of progress of 67 m/week and ahead of programme. The best daily progress was 32.4 m with the best progress on a 6-day week of 153 m. The TBM is now having a minor refurbishment and will start the remainder of its drive in October 2007, with an estimated completion of the drive in March 2008.

The second TBM started its drive in Febru-ary 2007 and on September 10 had completed 2.36 km of the drive to Traingeln station. The best six-day weekly progress is also 153 m. However with the recent change, in late August, to a 7-day week cycle the best weekly progress has increased to 185 m. The drive is expected to reach Triangeln station to complete the second breakthrough in the next few weeks. The best daily progress for the second drive has been 36 m.

The rate of progress for the remaining 2.1 km from Triangeln station to the reception shaft in Contract E101 is expected initially to remain high, but to reduce as the TBMs start to enter the wetter, more fractured ground in the north.

TrianGeln sTaTionThere was always great concern about the construction of the only bored tunnel station at Triangeln. The environmental court ruled that the ground water in the vicinity of the station must not be lowered by more than 0.3 m and a water re-charge system has been installed with 80% of the discharged water from the excavation being used in the recharge. The recharge system has worked well and there has been very little drawdown and well within the court figure. This has been helped by the more competent than expected limestone with fewer joints and a lower permeability.

The station has a 250 m-long cavern, 28 m-wide and 14.5 m-high with cut and cover boxes at each end for access escalators, lifts, staff quarters and equipment. Inside the cavern is a 14.5 m-wide central platform with a row of cen-tral columns. The station is 25 m below ground level with 10 m of cover to the limestone.

The cavern has been excavated in eight stages.

The first two stages were the top heading and bench for the central columns which were excavated with Voest Alpine road-headers from both ends. The base slab and large oval columns were then cast. The roadheaders then excavated the two large side heading with top headings, bench and invert, with ground support of lattice girders, rockbolts and shotcrete. The final linings will be cast following the dragging of the two TBMs through the cavern.

cross PassaGes and sHafTsCross passages are being provided at approxi-mately 340 m centres. There will be 13 cross pas-sages including one in the cut and cover tunnels. The first two cross passages in the bored tunnel are currently under construction. The ground be-tween the two tunnels was dewatered and grouted in advance. The openings for the cross passages extend over three rings. The load between the three rings and the adjacent rings is transferred through three square shear pins with dry pack concrete in each of the three segments above and below the opening. The segments forming the opening are then cut. There is no temporary support to the ring during the excavation for the cross passage. The 4.5 m internal diameter horse-shoe-shaped cross passages are lined with insitu reinforced concrete with a steel shutter of half the cross passage length.

souTHern cuT and coverThe 360 m-long cut-and-cover south of the bored tunnel was the first civil works to be constructed under the bored tunnel contract. The excavation was carried out within steel sheet piled walls, except for the headwall with the two eyes for the start of the bored tunnel which were concrete piled. The excavation was dewatered with water recharge wells outside the cofferdam.

A permanent dewatering system where 95% of the dewatering water is recharged in a sealed system operates at the open retained cut south of the cut-and-cover.

MalMö cenTral sTaTion The Malmö central station contract includes the reception shaft for the two TBMs. The shaft is part of the cut and cover west of the central station and will be handed over the bored tunnel contract for a period in March 2008 for the arrival

and dismantling of the two TBMs, after which it will be handed back to the station contractor for the completion of the cut-and-cover works.

The 700 m-long cut-and-cover to the central station has two tracks at the reception shaft, a 150 m-long crossing, and enters the station as four tracks. At the reception shaft the excavation has been carried out within diaphragm walls. The main length of cut-and-cover has been excavated within steel sheet piled walls and the works are now well advanced.

Traffic diversions and temporary closures have taken place to enable the cut-and-cover works to proceed. A sophisticated monitoring system for the dewatering and recharge is combined for the central station. The environmental court ruled that the water table outside the excavation must not be lowered by more than 0.3 m with a minimum of 80% of the dewatering water recharged. The system has worked well and has achieved these criteria.

Malmö central station is located to the north of the existing station and has two 11 m-wide island platforms, 320 m-long. The station is 8.5 m-10.0 m below ground level. The opportunity is being taken to modernise the central station and to achieve an exciting integrated system between new and old. The new bus station to the south of the existing station is already in use.

The excavation for the station is within a steel sheet piled cofferdam, except where it is close to existing buildings where diaphragm walls have been used. A sophisticated monitoring system is being used to monitor ground movements and adjacent structures.

ProGraMMeThe project is currently ahead of programme. The civil works – nearly 50% completed – are scheduled for completion in April 2009 and the link opened in 2011.

The editor is grateful to Citytunnel and technical manager Henrik Christensen for taking the author round the site and for illustrations and photo-graphs and for permission to publish the article. Thanks also to Herrenknecht for providing information on the project

ProjecT: Sweden

Shutter shown in cross passage

16-17WT0710.indd 17 10/10/07 15:23:55

An environmentally-sensitive water project in India includes the world’s longest ‘no intermediate access’ TBM-driven tunnel

TBM launch chamber and assembly area at the outlet portal

The Srisailam reservoir – inlet portal area

www.ugc.basf.com

07

MEYCO Equipment Division of BASF Construction Chemicals Europe AGHegmattenstrasse 24, CH-8404 Winterthur Phone +41-58-958 27 00, Fax +41-58-958 37 07

What Carl Ethan Akely began in 1907…

19

MEYCO® Equipment

je länger – je besser100 years shotcrete

October 2007

18PROJECT: India

In the drought-prone region of India’s Andhra Pradesh state, a massive irrigation and water-transfer project is becoming a

reality. More than 100 km of tunnels will bring water from the Srisailam Reservoir on the Krishna River to 1,200 km2 of farmland and 516 villages.

The tunnels, which pass under sensitive environmental areas, including India’s largest tiger reserve, will require drill and blast, as well as tunnel boring. To accomplish the job, contractor Jaiprakash Associates Ltd (JAL) will use two 10 m-diameter Robbins double-shield TBMs, assembled on-site, to bore a 43.5 km-long tunnel.

WaTER fOR ThE PEOPlEThe Alimineti Madhava Reddy (AMR) Project will transfer surplus water from the Srisailam Reservoir to the plains of the Nalgonda District for the Andhra Pradesh Government. Two main tunnels (T1 and T2) will carry the water under gravity. At 43.5 km, T1 will be the world’s longest TBM-driven tunnel without intermediate access. The tunnel will receive water from a head regulator, currently being constructed on the foreshore of Srisailam Reservoir. Water will flow through T1, which will connect to T2 via a balancing reservoir on the Dindi River.

A number of balancing reservoirs will be built, using central masonry in overflow sections and rock-fill in non-overflow sections. JAL’s senior vice-president, Anil A Kamat, explains: “Balancing reservoirs are required to cross all the valleys and rivers along the system route. The reservoirs will also be used as storage facilities for overflow.”

Drill-and-blast work began on the 7.3 km-long T2 from the outlet side in August. The 8.7 m-diameter horseshoe-shaped tunnel will be lined with shotcrete and built within four years. Designing the technology to bore the tunnel required consideration of the geological conditions and long distance involved.

The two Robbins TBMs for T1 form part of the largest, single TBM order in history, signed

between Robbins and JAL in May 2006. The complete contract includes two TBMs, back-up systems, continuous conveyor systems, spare parts and personnel.

lOngER TunnElsGeological conditions in T1 consist of quartzite zones up to 450 MPa UCS, layered, and separated by shale and granite (160-190 MPa UCS). Four large faults along the route are thought to contain fractured ground

with minor water seepage, although the remainder of the tunnel is expected to be dry. Two double-shield machines were selected due to the geology and location of the tunnel – just 500 m beneath the Nagarjuna Sagar-Srisailam Tiger Reserve.

The machines will use back-loading 20 in-diameter cutters for more efficient excavation and longer cutter life. Specially-designed drive motors allow each machine to run at a higher than normal rpm, compensating for the low penetration rates expected in hard rock. In squeezing ground, each cutterhead is capable of vertical movement to allow for over-boring.

Each machine will install 300 mm-thick concrete segments, which will serve as a final liner to create the finished tunnel diameter of 9.2 m. As the TBMs bore, invert segments will be laid directly on to the excavated surface and concrete rings will be bolted on in a 6+1 arrangement. The segment rings are stablised through a combination of pea-gravel injection and grouting to fill the annulus outside the lining.

A probe drill on each of the machines will be used to verify the geology 30 m ahead of the

Boring a new world record

Boring a new world record

18-19WT0710.indd 18 10/10/07 15:42:30

TBM. The drill can rotate 360º and serve as a grout-consolidation drill. Water accumulating at the tunnel face will be pumped out by large, specially-designed, 40 kW dewatering pumps, located on the back-up. Weep holes bored into the concrete lining will help to relieve external groundwater pressure.

A newly-designed data-logging system on each machine monitors TBM performance. Real-time meters measure parameters, including cutterhead motor amperage and power, and gripper-cylinder pressure. Data can be generated in a graphic form to view trends over time.

“The data-logging system on these machines is more advanced than those previously used on our TBM projects,” says Dale Hobbs, a Robbins electrical engineer. “We will monitor a greater number of parameters and equipment perform-ance will be examined during each ring build.”

Robbins engineers designed the long tunnel’s muck removal system for optimal performance.

The entire continuous-conveyor system will be broken up into short flights, with multiple drive motors, with belt added inside the tunnel, as required. Two 914 mm-wide, steel

cable, belt-conveyor systems, each of 22.5 km in length, but split into two equal sections, will operate from either side of the tunnel as the TBMs bore. Muck will be recycled as rock-fill on many of the project’s balancing reservoirs.

On-siTE assEmBlyBoth machines are being assembled on site in a process scheduled to take around three months. Gantry cranes of 170 t capacity will hoist the machine components into the launch pit. The two machines, including cutterhead, gripper system, forward shield and telescopic shield, will be assembled in a concrete ‘cradle’ before being

advanced. The TBM will crawl forward by reacting against invert segment pieces, installed progressively up to the tunnel entrance.

Drilled-and-blasted disassembly chambers will be used for TBM removal, each of which

will include a poured concrete invert and installed 170 t gantry cranes. The entire project is expected to take about 60 months to finish and should be operational by December 2012.

The editor is grateful to the Robbins Company for its assistance in the preparation of this article

www.ugc.basf.com

07


What Carl Ethan Akely began in 1907…

19

MEYCO® Equipment


19PROJECT: India

“Data-logging on these machines is more

advanced than on our TBM projects”

Pre-assembly of the front shield before shipment to the jobsite for full TBM assembly

18-19WT0710.indd 19 10/10/07 15:42:35

As part of significantly expanding its capacity in the European electricity market, Austrian Vorarlberger Illwerke

AG is constructing the huge Kops 2 pumped-storage power station, which will have a turbine output of 450 MW. Work on the €30 million project began in September 2004, with commissioning scheduled for 2008.

A major part of the project involves the construction of a huge, underground cavern, housing an enormous machine hall. The extensive concreting required for it will be undertaken by one, stationary, BSA concrete pump and one stationary concrete-placing boom, operated alternatively on two, tubular columns. Work will continue around the clock on a three-shift basis.

Like the Kopswerk 1 power station in nearby Montafon, the new, pumped-storage power station uses water from Kopssee lake. The project involves the construction of Sections 1 and 2 (pressure tunnels, surge tank and pressure shaft), as well as Section 3 with its machine chamber and transformer hall, not to mention supporting and underwater systems.

Section 3 is being worked on by a consortium made up of Beton- und Monierbau Gesellschaft mbH (Innsbruck), Alpine Mayreder Bau GmbH (Salzburg/Wals) and Ed.Züblin AG Zweigniederlassung Tunnelbau (Stuttgart), under the project management of Jäger Bau GmbH (Schruns).

60 m-high hall from rockImpressive is hardly the word to describe the machine chamber. Located around 150 m deep inside the mountain, the 88 m-long, 60 m-high and 30 m-wide cavern forms an essential element of Kopswerk II. It is reached via an entrance tunnel from the Silvretta highway, between Gaschurn and Partene.

Blasting began in January 2006, with excavation proceeding in one crown section, with two wall headings and a core. Four layers of structural-steel lattice and a layer of shotcrete, measuring about 100 mm-thick per reinforcement, provided safety during excavation. Numerous pre-stressed strand anchors of up to 32 m-long helped to maintain long-term structural integrity.

Three reinforced, turbine, headrace tunnels from the high-pressure distribution pipe flow into the machine chamber, along with the driving water flow, which passes through the pressure tunnel and shaft from a fall height of 800 m, driving the turbines’ impeller blades.

Stationary boom can moveCast in-situ concrete is being used to form the six underground stories and assembly level. Over 39,000 m3 of concrete will be required to form the machine chamber. The floor and ceilings of the enormous rock hall are up to 4 m thick while the walls, up to 8 m high, are constructed in thicknesses ranging from 0.2-4 m.

Given the chamber’s enormous dimensions, two stationary, concrete booms would normally have been necessary to ensure a uniform distribution of concrete. However, having consulted Putzmeister engineers, the consortium decided to install one MX 28-4 stationary boom, operated alternatively by two tubular columns.

Defining features of the unballasted MX 28-4 stationary, concrete-placing boom include the flexible Z-fold system of the arm assembly, which can also be used to concrete individual base sections of the turbine head-race tunnels,

and the overall length of the two tubular columns from which the boom is operated. By placing several tubular columns on top of one another (in lengths of 4, 6 and 10 m) they can be adapted to the building progress and extend-ed to a maximum height of 40 m during the final stage of the Kops II chamber. Additional stability to the tubular columns is provided by two braces, at heights of about 18 m and 24 m, anchored into the corresponding intermediate ceilings.

The boom is supplied by a stationary, concrete pump, connected to the MX boom

and its two tubular columns via a 150 m-long delivery line (DN 125). The BSA 1408 E is driven by a 75 kW electrical motor and achieves a delivery rate of 79 m³/h or 71 bar concrete pressure in rod-side operation (full side is 53 m³/h or 106 bar). By using less equipment, concrete can be applied economically.

Austrian PM subsidiary Hans Eibinger (Söding) has trained four

operators to use the MX stationary boom and BSA concrete pump. Eibinger service

engineers had helped previously in the installation of the tubular columns and

setting up the concrete-placing boom.The neighbouring transformer chamber,

measuring 35 m-long, 16 m-wide and 20 m-high, is also an imposing piece of structural engineering. The placement of concrete for the foundations, wall-form work and ceilings was partly conducted with a truck-mounted concrete pump, BRF 24-4.09 H, whose ZR fold-boom had slip characteristics. Around 2,200 m³ of concrete was poured. The transformer chamber’s shell was completed in November 2006.

low water/cement valueThe standard formulation during construction was concrete of stiffness class C25/30, made on-site in its own dedicated mixing plant. Generally, a water/cement (w/c) value of as low as possible is used to limit the hydration heat for the solid components. In warmer seasons, the ratio of cement to fly ash is changed from 230 kg/90 kg to 200 kg/120 kg per m3.

The editor is grateful to Jürgen Kronenberg of Putzmeister AG for his assistance in the preparation of this article

chamber musicShotcreting on a huge scale is taking place cost-effectively in an Austrian power station

October 2007

20technology: Sprayed concrete

Shotcreting inside one of the headrace tunnels

20WT0710.indd 20 10/10/07 10:41:16

21EQUIPMENT: Sandvik

Ë

VillagerS toiling on the terraces, set against the spectacular backdrop of the Himalayan foothills of northern India,

may be oblivious to the frenzied tunnelling going on below them, which is churning out what is set to become one of India’s main hydroelectric projects.

Centred on the Sainj River, a tributary of the Beas River in Himachal Pradesh, the project is being built for India’s National Hydroelectric Power Corporation (NHPC) in conjunction with the Himachal Pradesh Government. The scheme is due to be completed in 2010.

Originally a three-stage project, the first had to be abandoned before it ever got off the ground due to environmental considerations. As a result, Stages 2 and 3 now represent the two halves of a giant scheme that will generate

electricity of 800 MW and 520 MW respectively for the North Indian electrical grid.

Tunnelling in the Himalayas can be a difficult process. Challenging rock conditions, instability in some areas, and logistical problems brought by seasonal rain and snowfall can make tunnelling a hard slog. Although drill and blast has been the usual method for constructing Indian tunnels, Stage 2, begun in the second half of 2002 and now nearing completion, has used two types of TBM: an open- and a double-shield machine. However, frequent failures at joints and rockfalls hampered progress and, as a result, the work has proved highly complex.

Stage 2 was the first time that a TBM was used in India to bore an inclined shaft, but it also demonstrated that when conditions become adverse without warning, the consequences may be more problematic for a TBM-driven tunnel than for one excavated by drill and blast.

Stage 3 of the Parbati Hydroelectric Project is

Himalayan challenge

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MEYCO® Equipment



Stage 3 portal

Drill and blast takes over from TBMs in Stage 3 of this ambitious Indian hydropower scheme

21-23WT0710.indd 21 10/10/07 15:36:13

Ë

October 2007


based at Kullu and located downstream from the Stage 2 powerhouse. It will use regulated discharge from Stage 2, along with inflow from the Sainj river and the Jiwa Nalla stream. A 43 m-high rockfill dam will receive water from the tailrace of Stage 2. After power generation in its own tailrace and powerhouse, Stage 3 carries the water back to the Sainj and, ultimately, the Beas rivers. Consequently, no major diversion of the river is needed. The rock being encountered in Stage 3 comprises mainly schistose quartzite, mica schist, dolomites and granite gneisses, with joint infillings of clay and fluvio-glacial material.

Stage 3 tunnelling work involves:Ë�A 7,875 m-long headrace tunnel of 7.25 m in

diameter. As of August 31, only 840 m had been completed. Poor strata, consisting of phyllites and quartzites, had been encoun-tered, causing loose fall and cavities.

Ë�A 2,713 m tailrace tunnel, of which 1,100 m has been excavated. Work is ahead of schedule.

Ë A 13 m-diameter, 114 m-high surge shaft; pilot hole drilled.

Ë Two pressure shafts, one of 375 m and the other 345 m, bifurcating into four 3 m-diameter penstocks.

Ë An underground powerhouse, 123 m long,

22 m wide and 44 m high, equipped with four 130 MW-capacity generating units. MAT has been excavated.

Early last year, NHPC awarded a contract worth US$107.6 million for Lot 1 of the project to a consortium, comprising Larsen & Toubro (L & T) and Patel Engineering, to build the diversion tunnel, rockfill dam and cut-off wall, desilting chambers, underground works and a 5.8 km length of the headrace tunnel.

Also awarded at the beginning of 2006 was the US$147 million Lot 2 contract, to the Jager-

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Gammon consortium, for the construction of the powerhouse and associated underground works, including part of the headrace tunnel, the surge shaft, pressure shaft and tailrace tunnel, including adits.

The conditions where most of the Stage 3 tunnelling is taking place have indicated that drill and blast would be more suitable than TBM boring. This, therefore, involves using a fleet of drilling and rock-bolting machines, with shot-crete and steel sets to stabilise the excavation, and telescopic folding shutters for the final lining. Drill and blast was also the obvious choice for the powerhouse excavation.

Nine underground drilling rigs and rock drills for drilling and bolting are helping to cut through Stage 3’s complex rock. Jager-Gammon is using four Sandvik Axera T08-290 rigs and an Axera T08S-290C, while L&T Patel has four Axera T08-290 rigs. Mahabirsingh Chauhan, Sandvik’s regional head of service engineering, said the Jager-Gammon JV had taken delivery of four Axera T08-290 jumbo rigs, equipped with two drilling booms and one basket boom. These can drill holes of up to 51 mm in diameter at a rate of 3 m per minute.

There is also an Axera T08S-290C rig with two drilling booms and one basket boom; the machine differs from the other four units in being equipped with TCAD (Tamrock Computer Added Drilling) and TPC electrical controls. Drilling is faster thanks to the high-power drifter, while the computer helps to give even greater precision to the tunnel profile. This unit is being used where timing is particularly sensitive, such as on Gammon’s part of the headrace tunnel.

56-MoNTH scHEdUlEGammon’s senior project manager, Rajendra Singh, said it is running to a 56-month schedule and its contract is due for completion in the second half of 2010. He said Gammon had completed around 8% of the excavation work at the end of April. “Up to this period, we had drilled approximately 221,000 drill metres, using mainly 45 mm-hole diameters on the face drilling and 38 mm-hole diameters for the rockbolt drilling,” said Mr Singh.

Since the date of commissioning, Sandvik has assigned three engineers to care for all five machines around the clock, having so far achieved availability of over 90%. According to Rajendra Singh, the tailrace tunnel is progres-sively ahead of schedule, adding that, on the main access tunnel, the 1:10 slope had been a challenge for the drill-and-blast method. He explained: “Because of the high gradient and excessive seepage of water, the biggest challenge was to drill and charge the bottom hole, but we’ve been happy with the progress.”

The Axera TCAD is being used on the 7.25 m-diameter horseshoe-shaped headrace tunnel that

“Stage 2 was the

first time a TBM was used in India to bore an inclined shaft”

Concreting the dam

21-23WT0710.indd 22 10/10/07 15:36:21

Intake concreting


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is being progressed with full-face excavation. “We are drilling 90-100 holes of 45 mm in diameter and a depth of 4 m per cycle, using a V-cut drilling pattern,” said Mr Rajendra. “Tunnelling work is being assessed in excavation cycles, with drilling, blasting, excavation and support constituting one cycle. Working on a 24-hour basis, tunnelling is progressing at the rate of approximately three cycles every two days on average, with an average 3.2-3.5 m advance being achieved per cycle.”

The L&T-Patel consortium is using four Axera T08-290 jumbo drill rigs, equipped with two drilling booms and one basket boom, and high-power HLX 5 hydraulic rock drills. Again, the full-time presence of an engineer on site has helped to achieve 90% equipment availability.

“We are on schedule, even though the rock conditions are very poor,” said L&T-Patel project manager SK Upadhyay. “Outside the tunnelling works, we also have instability to face when trucking the spoil down to the disposal areas because rock falls and mud slides along the haul road can often disrupt the works.”

Both contractors are using Sandvik 45 mm drill bits for face drilling and R28 38 mm bits for rock bolting, and both use spherical buttons. In

addition, both grind their drill bits every 300 drill metres, with three to four grindings achieved for each bit, and an average of 600 drill metres per bit. L&T has a mobile grinding unit that travels between the machines and collects the bits, and grinds them on-site ready for refitting, while Gammon has a stationary grinder inside its main workshop.

The drill rods for Gammon are R38-R32 and 4.3 m in length for the face drilling, and the average life of these is 4,500-5,000 drill metres. For rock bolting, R38-R28 rods are being used, also 4.3 m in length, returning an average life of 3,000-3,500 drill metres.

L&T is using R38-R32 drill rods of 4.6 m long

for the face drilling, achieving an average life similar to Gammon. For rock bolting, L&T is using R38-R28 rods of 4.6 m long with an average life similar to Gammon. In each case, the drill depth is 4 m, achieved with 90-95 holes being drilled per cycle over 2.5 hours in total.

For the explosive, water-resistant Powergel is used. Cartridges are packaged in plastic film, which readily splits during tamping to maximise coupling and bulk strength within a blasthole. The high resistance of this type of explosive to dynamic desensitisation makes it suitable for use in tunnelling and shaft sinking in the Himalayas.

Machines and drilling tools were supplied by Sandvik Asia Ltd through its Indian HQ in Pune, and all spare parts are being supplied direct from Sandvik’s Asia-Pacific regional HQ in Singapore. There is also a permanent comple-ment of Sandvik engineers on the site, reporting to the Pune office, as part of the company’s policy of working directly with a customer, rather than as an outside supplier.

The Editor is grateful to Sandvik Mining and Construction for its assistance in the preparation of this article and to M.Madan of India’s National Hydroelectric Power Corporation for his input

21-23WT0710.indd 23 10/10/07 15:36:23

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Wirth.indd 1 10/10/07 11:48:41

October 2007

25

TUNNELLING is a truly global business, ranging from urban centres to the most inhospitable of regions. Scaling may be a

part of the tunneling process and involves remov-ing loose rock prior to the installation of ground support as part of the excavation cycle in hard rock or mixed ground. It is one area where a surprising amount of commonality exists for all tunnels. This does not mean, however, that in-novations are lacking and there are a number of potential crossovers between drifting in hard rock mining, and civil tunnelling.

One of the most important skills taught to any new underground worker is safely entering the workplace and making sure it is safe. Barring down is second nature to all good miners, and in-volves checking the ground by sounding it with a pinch bar and scaled to remove dangerously loose ground. Or seeking advice and possibly rock bolt-ing or otherwise supporting large loose ground that cannot or should not be brought down.

In many countries, having a suitable scaling bar at the face is a statutory requirement and all the various current practices for scaling cannot

replace this personal reading of the ground conditions.

Scaling is a prerequisite of most non-shielded, open-face tunnelling, whether hard rock or mixed ground. In many people’s minds it is often associ-ated with drill and blast tunneling, where scaling takes place as part of the activity cycle between mucking out and installation of ground support, or earlier after venting of blast fumes, depending on the mucking system employed.

The three main categories of scaling currently being used in tunnels are: hand scaling using a bar; mechanical scaling using an impact hammer to break and vibrate loose material; and mechani-cal scaling using picks to claw and drag loose down.

IMPACT SCALINGAtlas Copco complements its range of drill rigs for tunnelling applications with the Scaletec MC scaling rig. This state-of-the-art articulated rig features Atlas Copco’s Rig Control System, (RCS), to facilitate precise rig positioning and control, a 375 J impact energy hammer with dust suppres-

sion and automatic lubrication, and a specifi cally designed hydraulic boom, all mounted on one of the company’s M-series carriers that provides articulated steering and four wheel drive.

The Scaletec MC can scale a longitudinal profi le ranging in excess of eight metres above the roadway to nearly two metres below the roadway. For a fi ve metre high tunnel, it can cover nearly six metres either side from a single set-up.

Following service trials at Sweden’s Malmber-get mine, Atlas Copco upgraded its scaler with new features such as a new operator chair with built-in shock absorber, a shovel blade at the front used in place of jacks to stabilise the rig for operations, and relocation of the hydraulic hoses to provide better protection from rock fall.

Standard equipment on the scaler includes a FOPS-approved cabin to protect workers, cable reel and integrated diagnostics with logging. Optional extras include a high pressure rock cleaning device, air conditioning/heating and a CD changer.

Many projects may involve the less elaborate option of a rubber-tyred or tracked excavator

Scaling options in today’s tunnelsPatrick Hudd looks at the main methods of scaling and some of today’s scaling rigs and discusses some discernible trends

EQUIPMENT: Scaling

Atlas Copco’s Scaletec MC scaling rig features an SB300 hammer and boom mounted on an M-series carrier

Ë

25-27WT0710.indd 25 10/10/07 16:02:58

October 2007

26

fi tted with a hydraulic hammer. Sandvik’s Rammer range of hydraulic hammers are typical of the hammers usually chosen for such applications.

Of the Rammer offerings, tunnellers in the mar-ket for a potential scaling hammer will probably be interested in the mid-range, E-series. Among the selling points claimed by Sandvik for this line are power and reliability, ease of wear on the car-rier and operator, plus ease of maintenance.

The E 65 Tunnel hammer has a working weight of 1,345 kg and requires a carrier in the range of 18-26 tonnes. The hammer gives an impact rate of between 450-800 bpm.

A larger range includes the G-series hammers such as the G-90 Tunnel. Signifi cantly bigger, this weighs 3,120 kg operating and delivers a 300-480 bpm impact rate. The carrier requirements are suitably increased to 35-55 t and as such, the hammer is possibly positioned primarily for the excavation market, with scaling a secondary concern for the potential purchaser.

The tunnel variant of Rammers are said to be designed to match the requirements of a tunnelling application and include dustproof housings, water jets to reduce the dust caused by the operation and abiity for horizontal operation as standard.

In a similar vein to the Atlas Copco offering, Normet offers the Scamec 2000 family, which it hails as the “number 1 system for your tough scal-hails as the “number 1 system for your tough scal-ing” based upon the company‘s 40 years experi-ence in building carriers and mobile machinery.

However, this is a slightly hybrid machine, in that it offers both impact and pick-scaling. Normet said the impact hammer is dimensioned for loosening rock in non-systematically jointed rock conditions. Normally used on hard rock, the rock conditions. Normally used on hard rock, the hammer cradle includes a full range of movement hammer cradle includes a full range of movement for the impact tool, accurate targeting of the area to be scaled and fast hammering down of the rock. The double tooth pick arrangement that may alternatively be used permits effi cient barring down of rock that has a systematically bedded joint structure. Being most suitable for softer rock, Normet said the pick, “is also used for occasional up-keep and periodical scaling on hard rock surfaces”.

Citing ease of operation, Normet claims that as well as giving higher quality scaling and so reducing the risk of accidents, the Scalemec “also makes it less tempting to scale with mining machines not designed for this purpose, such as drilling jumbos and loaders”.

PICK SCALINGSandvik offered the Brøyt line of products follow-ing acquisition. These stalwarks of the tunnelling excavator shovel genre were so fast at loading trucks that idling time between loads could be used for scaling. The Brøyt 600s, for example, offered a quick hitch attachment that allowed for fast changes to a scaling pick that had a 10 m reach. With the standard bucket, scaling using the bucket teeth as picks was able to be carried out with up to 8 m reach.

The advantage of scraping rather than impact to remove loose material means that the surrounding rock is not loosened by the hammer which might

EQUIPMENT: Scaling

Multi-Scaler is for frost and rock ripping without fracturing the wall

Ë

25-27WT0710.indd 26 10/10/07 16:03:04

October 2007

27

otherwise lead to excessive scaling by unravelling. The shovels had enough power to clear the loose material in a single pass, leading to a very fast operation. A further saving is the amalgamation of the mucking and scaling units into a single piece of equipment.

Standard excavators can also be equipped for pick scaling by means of special attachments. These may be as simple as a pick or narrow bucket, or as complex as a hydraulically-driven cutter header for scaling and possibly more involved profi ling applications.

One interesting attachment under development in North America is the Multi-Scaler by Leading Edge Attachments Inc. It was originally developed under the “Shanks On An Arc” patented concept for utility contractors involving applying one tooth at a time on a constant radius for frost and rock ripping. Mining customers bought Multi-Scaler – a raked back version of the original ripper which, according to a Leading Edge Attachments spokesperson, is able to “scale a wall releasing all of the loose pieces without fracturing the wall”. The spokesperson added, “one mine mentioned that they could de-scale a 15.2 m-wide x 7.6 m wall, in preparation for blasting, in about an hour and fi fteen minutes, whereas it would have taken them 2 hours and 45 minutes previously with a hammer.”

The company claims the Multi-Scaler has shown it can scale ten times faster than a single pointed scaler pick and four times faster than a hydraulic hammer. Another advantage is the operating cost, which is said to be much less than a hydraulic hammer due to the absence of hydraulic components or any consumables other than the picks. Capital costs are said to be even more greatly reduced.

WATERJET SCALINGSeen as a viable alternative to both manual and mechanical scaling is the third method which uses

EQUIPMENT: Scaling

high pressure waterjets, a technique that has un-dergone considerable development and continues to be advanced by the North American mining community. Historically, water scaling had been seen as more of a surface preparation prior to the application of a thin membrane liner to improve cohesion to the rock.

Talking to mining industry insiders, World Tunnelling has learnt that many confi gurations of Tunnelling has learnt that many confi gurations of Tunnellingwater pressure and volume have and continue to be evaluated, but currently 2,200 psi and 70 gpm seems a working optimum. High pressure is needed to propagate through fi ssures, coupled with high volumes to fi ll the opening voids. In the words of one source, “we need weight behind it to get it down”.

Tests carried out at Kiruna in Sweden, found that shotcrete adhesion strength was increased by a factor of three for high pressure water jet scaled surfaces when compared to low pressure cleaned surfaces. World Tunnelling has been told that the World Tunnelling has been told that the World Tunnellingkey parameter is to decide what you want and if the ground conditions are amenable to water jet scaling. The intrinsic surface preparation for shotcrete or liner, coupled with the coverage, yield better results than a miner with a bar or mechanical scaling, but it does not preclude the

most effective solution being a combination of more than one method.

The danger is overscaling, or in some cases, effectively mining with the water jet as it can be so effective. The scaled ground should be characterised as a keystone arch, with wedged loose material holding itself in place until ground support can be installed. To counteract overscal-ing, one needs a good understanding of the rock mass rating, (RMR), and what ground is expected to come down, rather than over or under-applica-tion of the scaling.

Sources said that various mining houses are seeking to form a loose collaboration to assess the use of water jet scaling in as many varied condi-tions as possible in order to further refi ne the work carried out to date.

SUMMARYThere are many scaling options for today’s tunnel-ler and every manufacturer is keen to stress the merits of their own equipment. With news that mining companies are trying to come together to pool knowledge and expertise about water jet scaling, perhaps there is also scope for a knowl-edge transfer between the tunnelling and mining disciplines for like processes.

A boom-mounted hammer

demonstrates mechanical

scaling using localised

impacts to break and vibrate down

loose material

25-27WT0710.indd 27 10/10/07 16:03:22

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Shotcrete.indd 1 10/10/07 11:17:27

The northern section of the Lötschberg base tunnel (Mitholz construction site) was con-structed between 2000 and 2006 starting

from the intermediate point of Mitholz, which was reached through an access gallery.The tunnel was driven both to the north and to the south. The Mitholz site included the excavation of 23.5 km of single-track tunnel with cross sections of 61 to 64m2 and 1.6 km of connecting galleries.

Tunnelling was conducted from preliminarily constructed caverns that were accessible through the 1.5 km-long, 12% sloped access gallery. The entire excavated volume totalled 1.8 million m3. Tunnelling was conducted by consortium ARGE Satco, made up of contractors Strabag, Rothpletz, Lienhard+CIE AG, Walo Bertschinger AG, VINCI GP and Skanska International Civ. Eng. AG. Drill and blast with shotcrete support, rock bolting, waterproofing and an inner lining in the equipped ‘east tunnel’ were some of the methods used.

CONCRETE SPECIFICATIONSConcrete type and specifications were defined by the project engineering team. In order to fulfil the client’s requirements, Die ARGE Satco defined the following:�

Ë�Production (delivery performance, safety of supply and availability).

Ë�Workability (oven time to three hours, pumpa-bility of max. 100 bar pump pressure, low risk of variability).

Ë�Early compression strength, formwork removal resistance (work and tact).

ËTotal costs.

Additional constraints were established which, in some cases, decisively affected the concrete mix, production, working and quality. The most important included:Ë�Procedures regarding Alkali Aggregate Reaction

(AAR) resistance, when using AAR-reactive aggregates.

Ë�Effects upon supply safety of aggregates (material processing).Ë�Variations in aggregates in conjunc-

tion with the processing of excavated material.

CONCRETE PRODUCTIONMobilbaustoffe AG undertook

concrete and shotcrete production at Mitholz by

using a custom-built concrete production plant located in an underground cavern that included a

twin shaft mixer from

SIMEN (batch size 2.25 m3 ) with maximum hourly performance of 80 m3. Three 100 t capacity cement silos were available per mixer, as well as 14 aggregate silos, each with a volume of 80 m3.

Hagerbach Test Gallery conducted quality control testing of concrete produced in a mobile laboratory set-up near the concrete plant.

AGGREGATES FOR PRODUCTIONThe excavated material of the Lötschberg generated from drill and blast operations was assigned a recycling classification and processed accordingly. From the processed muck at the Mitholz site, enough aggregates were obtained to enable self-sufficiency of the site. Surplus material was passed on to third parties while missing grain sizes were bought according to need.

After each round of blasting, geologists classified the excavation material in accordance with its recycling class. In addition to the petrographic evaluation, the suitability of raw material K1 was verified by testing as deemed necessary.

From the K1 material, the material processor prepared the following aggregates for concrete:ËSand 0-4 mm, unwashed.ËSand 0-4 mm, washed.Ë4-8 mm, 8-16 mm, 16-22 mm.

Recycled muck makes tunnel concrete greenAggregates from tunnel spoil can produce economical and sustainable high-quality shotcrete. R Weiss of Hagerbach Test Gallery, explains how it was done at the recently opened Lötschberg Base Tunnel in Switzerland

Aerial view of the Mitholz site showing extensive materials management

Testing for sulphate resistance Ë

“It will serve as a valuable

basis upon which future

structures can be

designed”

October 2007

29TECHNOLOGY: Sprayed concrete

29-32WT0710.indd 29 10/10/07 15:50:00

The quality of prepared aggregate sizes was monitored and documented by the material proc-essor in accordance with a testing plan within the framework of production control. Independent of production tests by the processor, specimens were systematically taken from concrete plant silos by the contractor and their grain size determined.

AGGREGATE vARIATIONSWhen processing aggregates from tunnel excava-tion material, the uniformity of the material and its handling is critical, especially sand. During rock crushing, raw material behaves in different ways depending on the geology and moisture content of the excavated material. The effects were especially apparent in unwashed sand.

During the start phase at Mitholz, one sand delivered by the processor comprised both washed and unwashed sand. The large fines fraction >0.125 mm of about 16% and large variations affected the amount of water needed for the concrete mix and made concrete production more difficult. The high water content limited the early strength development of shotcrete to an unacceptable level and the w/c ratio was considerably higher than 0.50. After a phase with approximately 13% 0.125 mm, the delivery was

modified to the originally planned ratios of unwashed to washed sand so that vary-ing site requirements and shotcrete mixes could be better accounted for.

Handling unwashed crushed sand was a critical factor, as it was susceptible to decomposition and often settled at the bottom of the concrete plant silos, requir-ing great effort to re-loosen. Furthermore, during production, concrete production workers were constantly attending to water requirements and mix consistency.

Visible variations in the consistency of shotcrete mixes increased the risk of change to the mix through uncontrolled water addition into the mix. The result would be lower concrete quality.

ALkALI AGGREGATE REACTION (AAR) RESISTANCEAggregates to be used for concrete production (mainly silicic limestone) were classified as reactive to highly AAR-reactive (microbar values over 0.2%). With the limitation of both alkali and cement content in the concrete mix, the client made allowances for the AAR reactivity of aggregates,

For shotcrete, Portland composite cement CEM II/A-M 52.5 with 10% limestone filler and 8% microsilica was used. The cement content was limited to smaller maximum grain size 420 kg/m3, instead of the more usual (for Switzerland) 460 kg/m3 and this affected decisively the shotcrete’s workability and early-strength development. The fines content of the shotcrete was approximately 590 kg/m3, of which 170 kg/m3 was 100 % crushed aggregate.

In unstable areas, a mix with 520 kg/m3 cement for face support and support in the area L1 was therefore specified to ensure sufficient

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Shotcrete resultsË

October 2007


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In addition to the suitability of excavated material, sufficient supply of aggregates to site had to be ensured. Therefore, the mix design for concrete and shotcrete had to take the rate of material extraction into account as far as possible. In an initial phase in which much more shotcrete than cast concrete was required, an insufficient quan-tity of 4-8 mm grain size was available. Dur-ing this phase, around one-third of the 4-8 mm requirement was procured externally. To account for the lack of 4-8 mm aggregate,

its use within the mix design was limited as far as possible, particularly in mixes for cast concrete (mainly invert concrete). Shotcrete mixes however could not do without the 4-8 mm variety and the substitution of 0-4 mm sand, because the quantity of water in the mix was already high and further increases could not be tolerated.The petrographic composition, the aggregate form and size distribution of aggregates produced on site differed from externally procured aggregates. Concrete mixes were versatile enough to accommodate any resulting variations.

Ensuring supplyearly strength development. In cast concrete, Portland cement CEM I and fly ash in ratios from 70/30 to 80/20% were used. The testing of the mix’s resistance to AAR was conducted by the client with LCPC performance tests.

CONCRETETest methodsVerifying the strength classification was conducted in accordance with SIA 162 on cubes for cast concrete and SIA 198 on drill cores for shotcrete. The water penetration depth under pressure, tested in accordance with DIN 1048 and SN EN 12390–8, served to verify the impermeability. Sulphate resistance was tested in accordance with the Swiss standard SIA 262/1, Appendix D.

To test sulphate resistance, six 150 mm-long drill cores with diameters of 28±2 mm were taken from test cubes, shotcrete testing boxes, or directly from the structure. The cycle of drying and saturation can lead to the transport of significant quantities of sulphate into a test specimen. The sulphate reacts with the constituents of the specimen resulting in an increase in volume and destruction of the concrete matrix. For evaluation, changes in length and mass are determined.

SHOTCRETE The graph shows that the shotcrete fulfils the strength requirements of classification B35/25. The average value of 290 tests was 49.2 N/mm2, with a standard deviation of 9.8 N/mm2. In comparison with cast concrete, the values for shotcrete deviated more widely, which is characteristic for the material.

Over 66 tests for water penetration, the average was 21 mm. The amount of reserve to

the limiting value was good at three standard deviations (9.1 mm).

INvERT CONSTRUCTIONThe cube compressive strength reached an

average of 47.0 N/mm2 with a standard deviation of 5.4 N/mm2. The strength classification require-ments for B35/25 were fulfilled. Impermeability re-quirements were also fulfilled with a good amount of reserve, with an average water penetration of Ë


29-32WT0710.indd 31 10/10/07 15:50:04

19.4 mm and a standard deviation of 7.7 mm. For sections with sulphate concentrations over 250 mg/l, high sulphate resistance concrete was required. The ∆l(DS3)-values from Mitholz were on average 0.2‰ for 17 tests. As a reference value for concrete with high sulphate resistance, SIA 262/1 requires a series value ∆l(DS3) of 0.5‰.

INNER LINING “SOUTH-EAST”The demands on strength (B35/25) and impermeability (water penetration 50 mm) were met with an average compression strength of 54.5 N/mm2 (standard deviation 4.5 N/mm2) and an average water penetration of 17 mm (standard deviation 6 mm) with sufficient reserve. The mixes were tolerant of construction variability and therefore constituted little risk.

Strength requirements were increased significantly to B80/70 for about 20 sections in a zone where rock conditions were very unfavourable. The concrete mix was adapted. Instead of cement CEM I 42.5, cement CEM II/A-M 52.5 with 400 kg/m3 and a maximum grain size of 16 mm was used. Production quality control was intensified. This difficult phase could be realised with an impressive

compression strength, on average, of 80.8 N/mm2 with a very good standard deviation of 3.2 N/mm2. The average value of water penetration in this concrete was 9 mm.

CONCLUSIONS AND OUTLOOkThe Mitholz experience proved that high- quality concrete can be produced from aggregates processed from tunnel excavation material. The project will serve as a valuable basis upon which future structures can be designed. Engineering design work conducted in accordance with the

Swiss standard SIA 260 must incorporate suitably chosen construction materials to deal with hazards of structural members. For concrete, this means the design engineer must determine the exposition class of the concrete, and accordingly, any further necessary requirements and proce-dures. Because the expected service life of tunnels usually exceeds 50 years, a performance-based design process in accordance with SN EN 206–1 should be applied.

For the tremendous cooperation at Mitholz, thanks must go to ARGE Satco’s personnel, concrete producer Mobilbaustoffe, client representatives and material processors. Thanks also to the site supervision team which generously provided the test data used in this report.

The editor is grateful to R. Weiss of VSH-Hager-bach Test Gallery Ltd for allowing the reproduction of this abridged version of his original paper, ‘Concrete and shotcrete with crushed aggregates: experience from the AlpTransit construction site Mitholz’, taken from Underground Space – the 4th Dimension of Metropolises – Barták, Hrdina, Romancov & Zlámal (eds). 2007 Taylor & Francis Group, London, ISBN 978-0-415-40807-3

Testing fresh concrete at an on-site lab

Ë

October 2007


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October 2007

33TECHNOLOGY: Innovation

Roof bolter raises the barTHE Roof Master 1.4 Automatic Roof Bolter has been co-developed and manufactured. Mine Master Ltd (Poland), with the support of KGHM Polish Copper plc, designed and produced the special chassis required to ensure the bolter was able to operate in low and difficult terrain; JH Fletcher & Co (USA) developed the bolting module.

The roof bolter can install 1.2 m-long bolts in working heights as low as 1.6 m, achieved by using a patented drilling system where both starter and finisher drill steels are used to allow the correct depth of hole to be drilled. Pre-loaded into a ‘bolt magazine’, when installed the bolts are tensioned to the required torque by a computer-controlled system.

The operator is housed in a protected, fully-enclosed, air-conditioned compartment on the chassis of the vehicle. Full automation ensures maximum operator productivity, so that once the bolt magazine is loaded, and the bolter is in position to start drilling, the operator is able to drill and install a roof bolt simply by pushing a button. The operator monitors progress by observing the bolting module and/or watching a display module located in the cab. This module also provides the computing power to control the operations.

Very hard strata are claimed to be drilled effectively thanks to the high-thrust rotary drill-ing system. Both dry dust collection and wet flushing systems are available.

The drill boom allows the bolter to install bolts over a 5.0 m-wide straight line and also has the ability to angle bolt.

Diesel engine-powered, the permanent four-wheel-drive articulated carrier is able to handle the severest of mining conditions. All drilling and bolting operations are electrically-powered. Operational for some 18 months, the roof bolter is now a proven and reliable concept.

Alwag supports Koralm exploratoryALWAG is supplying reinforcement and support products to the Paierdorf exploratory tunnel in Austria. The project forms part of the preliminary work being carried out before the construction of the US$2.46 billion, 32.8 km-long Koralm Tunnel between Graz and Klagenfurt.

Products supplied include the AT-Casing System and the recently-developed AT-Power Set self-drilling Vacuum Tube Spiles. The latter are used both for reinforcement ahead of the tunnel face and handling of the groundwater through coupled vacuum pumps.

Alwag’s patented AT-Casing System is being used at the Paierdorf site as a pipe roof system in combination with the AT-automation unit for pipe roof drilling. Its benefits include fast, safe and efficient drilling of pipe roof umbrellas for reinforcement ahead of the tunnel face. An Alwag technical support team is available to provide on-site advice.

Extensive geological surveys were carried out in 1998 near the proposed Koralm tunnel; before work begins on the final tunnel, a total of 11 km of exploratory tunnels will have been built. To achieve the best possible survey, the exploratory programme was divided into four separate lots – one in the eastern area and three in the western area.

As part of the exploratory programme, the Paierdorf lot in Carinthia is being constructed in two stages: first an exploratory shaft with a depth of 125 m, followed by an exploratory tunnel to the east and to the west. Thus, the shaft was constructed to gain access to the future tunnel level. As of July 2005, construction of the 5.1 km-long exploratory tunnel has been continuing and should be completed in 2009. However, difficult and changing ground conditions are hampering progress. Groundwater inflow has also caused problems.

Beethoven’s brother?USED by miners, tunnellers, demolition special-ists and armies, the Beethoven Exploder has been at the heart of traditional wire-based shot-firing for many decades.

Now, the Beethoven SparkMaster incorpo-rates the latest technology and looks set to meet the needs of explosive engineers who prefer shocktube-based systems. Designed with the shot-firer in mind, reliability is paramount given that blasting often takes place miles from base.

At around 700 g, the portable, solid-state unit has a robust, highly-visible, red case. It comes with a stout, weather-proof carrying case which includes a pouch for spare ‘sparkers’. During inclement conditions, the unit can be operated without being removed from the case.

Instead of rechargeable batteries, which can fail, the SparkMaster’s charge is provided by a set of replaceable batteries with a life of some 500 firings.

An LED warns when the batteries need to be renewed. One of the new concepts applied to the unit is that the charge is delivered to the fir-

ing shocktube by an inexpensive, disposable, sin-gle-use ‘sparker’, to avoid ‘dud’ firings.

Designed with safety in mind, the Spark-Master utilises a three-colour LED system to indicate status.

Requiring two-handed op-eration, the mag-netic safety key is inserted with one hand while the other presses the firing button as soon as the green LED lights up. The sparker then in-jects a spark into the shocktube.

The special chassis for roof bolting in low and difficult conditions was co-developed by Mine Master and KGHM Polish Copper

Alwag products, such as the AT-Casing System, are being used as part of an exploratory project in the Paierdorf tunnel in Austria

The Beethoven SparkMaster is designed for use by explosive engineers in all weather conditions

33WT0710.indd 33 10/10/07 10:42:05

34SUPPLIES AND SERVICESSUPPLIES & SERVICES

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reamer etc.2: Vermeer D80x100, approx. 2000h, year 2000, 750l aplex

pump, 620m rods3: Vermeer D50x100, approx. 4000h, year 2000, 500l kerr

pump, 500m rods4: Huette HBR 206D, approx. 2200h, year 1998, 470m rods

“We have TCI Three cone bits for all Ditch Witch terrar machines for 760 €”

October 2007

34WT0710.indd 34 11/10/07 10:21:51

No TBM company in the world has more. Experience.

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If it can be imagined, Robbins

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Robbins.indd 1 10/10/07 11:32:14

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