194TheMasterbu||der -March2012 www.masterbu||der.co.|nTunne|Eng|neern|gTBMsTBMsinndiaThetunne|TBMswereear||er emp|oyedpr|mar||y |n thewater supp|ysectorand|ater|nhydro-e|ectr|c pro|ects. ATBMwasused|rst|n lnd|a |n 1984or excavat|ngatunne|od|ameter 3.5metersunder apro|ectortheBombay Water Supp|y Scheme.A|though TBMsmadean entry |n ear|y1980s, convent|ona|dr|||andb|ast methodsrema|n predom|nant|n lnd|a.Desp|te, theprogressratesach|eved |ths|zeab|e|nvestments env|sagedor |nrastructure Wsector lNP 5tr||||on |n roads,lNP 1.2tr||||on |n hydropower, lNP 1.8 m||||on |n water andseweragesystems andlNP 1tr||||on |n metrora||pro|ects |n the12th p|an, tunne|worksarego|ng tobe|nthespot||ght. Andw|th|ncreased ocuson deve|opmento wor|dc|ass tunne||nrastructure, theTunne|Bor|ng Mach|nes(TBM)|ndustry |sexpected tow|tnessa|oto act|v|ty |n thecom|ng years.w|th such trad|t|ona|methodsbe|ng extreme|y |ow7.5mto81.0monmonth|yaveragebas|sbasedon thes|zeotunne|andactors||kegeography, one o thema|n reasonsor notus|ngTBMs or such tunne||obswastheh|ghproh|b|t|vecostothe|mported equ|pmentandprocedures|nvo|ved|n|mporto themodern equ|pment. However, whatwasnotcons|dered wasthattunne||ngby dr|||andb|ast methods, part|cu|ar|y |n sot rocks, otenresu|ted|n over-breakso theorder oBhavaniBaIakrishnaBhavaniBaIakrishnaNodarn T8Ns:nab||ng tha haxtwava oI|nIrastructura 0rowth |n |nd|a195 www.masterbu||der.co.|nTheMasterbu||der -March2012Tunne|Eng|neern|gTBMs10-15%|ead|ngtot|meandcost overruns.However, w|th ocuson qua||ty and t|ghtschedu|es, useo TBMshas become|mperat|vetoach|evesae tunne|||ngwh||emax|m|z|ngtherateoadvance|n excavat|on. Th|sadvantage hassomewhatosettheh|gh cap|ta| cost|nvo|vedw|th th|sequ|pment.S|ncethen TBMshavebeen used|nhydroe|ectr|c pro|ects, roadsandwatersupp|y butthesemach|neshavebeen|ate|y |n the||me||ghtor the|r ro|e|n the parto thetunne|, severa|mechan|sms or shotcret|ng, rockbo|t|ng, precast ||n|ngsegmentsandstee|r|bssupport arepresent.Wh||emoreandmorepro|ects|nlnd|aaresw|tch|ngtoTBM techn|que over convent|ona|techn|que, tunne||ng |n H|ma|ayashasa|waysbeen ama|orcha||engetopro|ectp|anners. The exper|enceso TBM |n Du|hast|and Parabat|havenotbeen successu|and thecontractorshadtoa||backon dr||| andb|astmethods. TheH|ma|ayangeo|ogy |squ|tevary|ngw|th o|dsand metrora||pro|ectso severa|metro-po||ses|n lnd|a. ln act, theGovern-ment, recogn|z|ngthes|gn||canceothesemach|nes|n hydroe|ectr|c and roadpro|ects,hasprov|dedu|| exempt|on rombas|c customsdutyandadd|t|ona|duty o customs(CvD) on tunne|bor|ngmach|nesandparts andcomponentsthereo or use|n the assemb|y o Tunne|bor|ngmach|nes used|n hydroe|ectr|c andh|ghwaydeve|opmentpro|ects.TBMsoperate|na|| k|ndso geo|og|es compr|s|nghardrock, sotgroundand m|xed-acecond|t|onsw|thh|gh overburden andh|gh groundwaterpressures. Theapp||cat|on rangeosotgroundmach|nessuch asearthpressureba|ancesh|e|dsor s|urrysh|e|dshavea||owedacons|derab|e expans|on o theapp||cat|on areasosh|e|dtunne||ng|ead|ngto|ncreased econom|c eas|b|||ty o thesetunne||ng systems. Thecho|ceo as|ng|eordoub|esh|e|dedTBM dependson the typeo rockstrataandtheexcavat|onspeedrequ|redandtra|||ngsupport mechan|sms. Doub|esh|e|dedTBMs arenorma||y used|n unstab|erock strata, or whereah|gh rateo advance-ment|srequ|red. S|ng|esh|e|ded TBMs, wh|ch are|essexpens|ve, are moresu|tab|etohardrockstrata.Beh|ndthesh|e|d, |ns|dethe|n|shed P|ctureCourtesy: www.opg.com"The softground tunnelingmarketisexpanding-particularlyin ndia andChina- and we would like tomeetthe growingrequirementsofcustomers inthese countries."LokHomePres|dent, Pobb|nsWorkersemerg|ngasaTBM breaksthrough under thelnd|acap|ta|, New De|h|196TheMasterbu||der -March2012 www.masterbu||der.co.|n|argenumber o sma||andb|gau|ts,thrusts, shear-zones. Moreover, therocks o Sh|wa||ksandLesser H|ma|ayasare,|o|nted, sheared, rag||eandweak.Thesetogether makeH|ma|ayan rocks ad||cu|ttunne||ngmed|a.Exper|enceshavesuggestedthat TBM excavat|onneedsmet|cu|ous p|ann|ngandsevera|prob|emscan be avo|ded| athorough s|te|nvest|gat|on|sdone. A|mostevery aspecto a tunne||ngpro|ect|s|n|uencedby the geo|ogyothearea.lnadequate geo|og|ca||nvest|gat|onandpoor ant|c|pat|ono thenatureandmagn|tude o prob|emsresu|t|n de|aysandh|ghercosto construct|on. Facedw|th cost andt| meconstra| nts, deta| | ed |nvest|gat|onsareoten comprom|sed resu|t|ng|n |acko qua||ty construct|onr|dd|edw|th prob|emsandt|meand costoverruns|nthe|ongterm.Pr|or understand|ng, obta|ned|n a correctmanner, o thegeo|og|ca|and geotechn|ca|cond|t|onso thes|te|s undamenta|or thedeve|opmentoundergroundworks. Probeho|esand theuseo geophys|ca|exp|orat|ontechn|quescou|dbeusedtoascerta|nthepresenceo groundwater. Advanced geophys|ca|methods||ketomograph|cana|ys|sandradar, though expens|ve,can becosteect|ve|n the|onger runpart|cu|ar|y|nH|ma|ayas.Forward prob|ngromaTBM dr|ven p||ottunne| or ama|n tunne||snotan a|ternat|veto an adequatepre-|nvest|gat|on. p to now, too||tt|emoney has|n genera| been spent on pre||m|nary |nvest|gat|ons.lthas|n actbeen demonstratedthat money spenton such |nvest|gat|ons|s great|y compensatedby thesav|ngs made|n termso construct|on costandt|me.Thecho|ceo TBM |sanother|mportantaspectthatneedsacr|t|ca| ana|ys|satp|ann|ngstage.The se|ect|on o theTBM shou|dthen be basedon the|nterpretat|onso th|s geotechn|ca||nvest|gat|onreport. Expert& |ndependentadv|ceshou|d besoughton these|ect|on o thetype and TBM. Last|y, |t |s the men beh|nd the mach|nethatmatter. An exper|enced Hybr|dEarth PressureBa|anceMach|ne(EPBTBM)bu||tus|ngOns|teF|rstT|meAssemb|y (OFTA).Narmadava||ey, |ocated|n Centra|lnd|asMadhyaPradesh state, |sadrought-pronereg|on or e|ght monthsouto every year. TheS|eemanabadCarr|er Cana||sparto thelnd|an GovernmentsBarg| D|vers|on Pro|ect, wh|ch w|||sourcewater romtheNarmadaP|ver to|rr|gate250,000acres(100,000 hectares)o |and.Thema|or trans-va||ey cana|w|||stretch 194km(120m|)romtheex|st|ngBarg|Damon theNarmada P|ver toar|dareas. Oncecomp|ete, theBarg|D|vers|on Pro|ectw|||transer 152cub|c meters(40,000 ga||ons)o water per secondtoKatn|, Satna, Panna, andJaba|pur d|str|cts, |rr|gat|ngover 100,000 hectares(250,000acres)o |and.Thecontractor, a|o|ntventureo M/sPate|Eng|neer|ng, SEW, andCoasta|Pro|ectsL|m|ted(CPL),s|gnedacontractw|th Pobb|nsor thesupp|y o a10.0m(32.8t)d|ameter EPB, aswe||astheback-upsystem, cutt|ngtoo|s, sparesandcont|nuousconveyor system. CPL a|sooptedor Ons|teF|rstT|me Assemb|y (OFTA)o themach|neatthe|obs|te, |norder toexped|tethepro|ectschedu|e.Thehybr|dEPBwascomp|etedus|ngOns|teF|rstT|meAssemb|y (OFTA)|n MadhyaPradesh, lnd|a on March 14, 2011. Acomm|ss|on|ngceremony ce|ebratedthe|aunch o theTBM atthe12km(7.5m|) |ongS|eemanabadCarr|er Cana|.The|aunch ceremony a|somarkedthe|rstt|meOFTAhasbeen usedon ahybr|dEPB. ThePobb|ns-deve|opedmethoda||owedtheTBMtobe|n|t|a||y assemb|edon |ocat|on, rather than |n amanuactur|ng ac|||ty. Cr|t|ca|subsystems, such asthee|ectr|ca|andhydrau||c systems, weretestedbeorebe|ng sh|ppedtothe|obs|te. Oncecomp|eted, thetunne|w|||havead|ameter o 9.2mand|sexpectedtobe operat|ona||n2013.Aworker stand|ng|ns|deoneo thetunne|screatedby the14TBMsusedby lnd|atoovercomethe cha||engeso at|ghtschedu|eor thecommon wea|th games.Tunne|Eng|neern|gTBMs Tunne|Eng|neern|gTBMsteamw|th astrong|eader |sthewayorward.ln lnd|a, theTBM market|s|arge|ydom|natedby Pobb|ns, Herrenknecht,H|tach|Zosen andSELl. ln 2008,Herrenknechtput|ntooperat|on anassemb|y p|antor tunne|||ngsystems andserv|ce|n Chenna|cover|nganareao 40,000squaremeters. Coasta| Pro|ectsL|m|ted, aHyderabad-based tunne|eng|neer|ngcompany recent|yacqu|red26%stake|n lta||an based SELl.W|th|ncreasednumbero tunne||ngpro|ects|n lnd|aexpectedto be|mp|ementedus|ngTunne|Bor|ng Mach|nes(TBMs), Coasta|Pro|ects standstobene|trom|tsassoc|at|onw|th SELlas|ta|sodes|gnsandbu||ds hard rock and sot ground tunne| bor|ng mach|nesandaux|||ary equ|pment. ln2009,BEMLL| m| teds| gneda Memorandao Agreementw|th NFMTechno|og|esor themanuactureotunne|bor|ngmach|nes|n lnd|a. NFMTechno|og|es|sthesecond|argest manuacturer o TBM|n thewor|dw|th a g|oba|marketshareo 20%. Lastyear,H|tach|Zosen Corporat|on estab||shed an lnd|an subs|d|ary, H|tach|Zosenlnd|aPr|vateL|m|ted(HZlND)|n Gurgaon tohand|etheg|antlnd|anmarketH|tach|Zosen de||veredtwo s|urry-typesh|e|dtunne||ngmach|nes tolnd|aor the|rstt|meor the Banga|oreMetrosubway construct|onpro|ect|nBanga|ore, KarnatakaState.ProjectsPulaSubbaiahVeligondaProjectAPobb|nsDoub|eSh|e|dTBM |s water. TheDoub|eSh|e|dmach|ne ut|||zess|xty-seven 20-|nch d|ameterback-|oad|ngcutterstocombatthe tough groundcond|t|ons. Spec|a||ydes|gneddr|vemotorsa||owthe mach|netorun atah|gher than norma| PPM, compensat|ng or |owpenetrat|onrates|n thehardrock. ln squeez|ng ground, thecutterhead|sa|socapab|e overt|ca|movementa||ow|ngoroverbor|ng. Themach|nea|sohasa probedr|||wh|ch a||owsor ver||cat|ono geo|ogy 30m(98t)aheado the TBM. The dr||| |s capab|e o 360` rotat|onandcan a|ternat|ve|y serveasagrout conso||dat|on dr|||. Large 40 kW(54 hp) dewater|ngpumps|ocatedon the back-up systemhavebeen spec|a||ydes|gnedtopump any water awayromthetunne|ace. AstheTBMbores,|t erects 300mm(12|nch) th|ck concrete segments|na61arrangement, mak|ng the|na|tunne|d|ameter 9.2m(30t).Muckhau|agerequ|resoneo themost extens|veconveyor systemsever used |n lnd|a. Thecont|nuousstee|cab|e be|t, the|ongests|ng|e||ghteverprov|dedby Pobb|ns, w|||extend19.2 198TheMasterbu||der -March2012 www.masterbu||der.co.|nbor|ngtunne| No. 2o thePu|aSubba|ahve||gondapro|ector Coasta|Pro|ects Ltd. (CPL), o theCPL/ H|ndustanConstruct|on Company (HCC)Jv. The ve||gondatunne|no. 2|s|ocated|nsed|mentary rock on the western marg|no theCuddapahBas|n, whereanumbero au|tsando|dsmakeor comp|ex geo|ogy. Pock|nc|udesquartz|tew|th|nterbeddedsha|e(60%)andsha|e w|th||mestoneandphy|||te(40%) rang|ngrom90to225MPa(13,000to 33,000ps|)CS. Twoma|or au|tsare expecteda|ongw|th someground Typ|ca|10.0mcrosssect|on o adoub|esh|e|dedTBMSh|e|dedTBMsaregenera||y usedor racturedrocksw|th thehe|p o concretesegmentstosupport theunstab|etunne|wa||sbeh|ndthemach|ne. Doub|eSh|e|dTBMshavetwomodes, |n stab|eground they can gr|p aga|nstthetunne|wa||stoadvance. ln unstab|e, racturedground, thethrust|ssh|tedto thrustcy||ndersthatpush o aga|nstthetunne|segmentsbeh|ndthemach|ne. Th|skeepsthes|gn||cant thrustorcesrom|mpact|ngrag||etunne|wa||s. S|ng|eSh|e|dTBMsoperate|n thesameway, butare usedon|y |nracturedground, asthey canon|y pusho aga|nsttheconcretesegments.Tunne|Eng|neern|gTBMs Tunne|Eng|neern|gTBMs"Herrenknechtndia Private Limited inaugurated the extension ofits manufacturing unit (assemblyhall,warehouse and steelmanufacturing unit) in Chennai on December 14,2011.Asndiais one ofthe fastest-growing marketsin the Asia-Pacificregionwith very high demand, the factoryset-up hasbeen expanded by 2,000m for a new assemblyworkshop,830m for the warehouseand 840m for the steel manufacturing unit.n these facilities Herrenknechtwill assemble and/or produce TBMsup to 9 meters in diameter,aswell ascutting tools,project-specificjobsiteequipmentand will handle spare and wear part."FrankHurst,Manag|ngD|rectorHerrenknechtlnd|aPr|vateL|m|tedkm(11.9m|)andrequ|resour ma|ndr|vesandthreebooster dr|ves. The mach|newasassemb|ed|n |ustourmonthsus|ngOns|teF|rst T|meAssemb|y(OFTA). OFTA|saprocessthata||ows mach|necomponentstobe|n|t|a||yassemb|edatthe|obs|te, rather than |namanuactur|ngac|||ty,typ|ca||y prov|d|ngsav|ngs|n termso man-hoursandsh|pp|ngcosts.AhugeHerrenknechtHardPock Doub|eSh|e|d|sa|socurrent|y atwork on thepro|ect. The2,800kWTBM |s bor|ngthe18.8k||ometer-|ongtunne|at depthso asmuchas550meters.Alimineti Madhava Reddy(AMR)ProjectAt43.5km(27m|), theA||m|net| MadhavaPeddy (AMP)Pro|ectw|||be the|ongesttunne|w|thout|ntermed|ate access|n thewor|dwhen comp|ete|n2012. The tunne| w||| transer |oodwaterromtheKr|shnaP|ver toar|dreg|onsolnd|as Andhra Pradesh state, prov|d|ng 2|rr|gat|on to1,200km(400,000acres) o arm|andandc|ean dr|nk|ngwater to 516v|||ages. Contractor Ja|prakashAssoc|ates Ltd. (JAL) wontheSD$413m||||oneng|neer-procure-construct contract|n 2005romtheAndhra Pradesh governmenttoconstructa headregu|atorandtwotunne|s, |nc|ud|ngthema|n 43.5km(27m|) tunne|. On May 26, 2006, JAL awarded acomp|etecontractw|th ThePobb|ns Company or two10.0m(32.8t) d|ameter Doub|eSh|e|dTBMs, aswe|| as conveyor systems, back-upsystems,spareparts, personne|, andtechn|ca| support. The|rsto thetwomach|nes was|aunched|n March 2008ater anunprecedentedons|teassemb|y. Botho themach|nes were|n|t|a||y assemb|ed ons|teus|ngtheOns|teF|rstT|me Assemb|y (OFTA)process. Geo|og|ccond|t|onscons|sto quartz|tezones upto450MPa(65,000ps|) CS, |ayered andseparatedby sha|eor approx|-mate|y 50%o the|ength, w|th gran|te (160to190MPa/ 23,000to28,000ps| CS)or therema|n|ng50%. Bothmach|nes eature back-|oad|ng20-|nchd|ameter cuttersor |onger cutter ||e|ntheabras|vecond|t|ons. Other des|gnmod||cat|ons |nc|ude spec|a||y des|gned dr|vemotorstorun each mach|neata h|gher than norma|rpmor opt|ma| penetrat|onrates|nthehardrock.NewDelhi MetroExtensionProject10HerrenknechtTBMs(EPB Sh|e|ds, d|ameter 6,460-6,640mm) provedthemse|ves|nDe|h|.For examp|e, they underpassedama|orra||way routew|thoutany d|srupt|onsto tra|n tra|c. A|ongonetunne|sect|on,theTBM unexpected|y hadtomasterrockormat|ons, wh|ch meantthat Herrenknechthadtode||ver anewcutt|ngwhee|tothecustomer topass th|sau|t zoneandavo|daTBMrecovery.Twomach|nesstartedtunne|||ngon|y a ew metersaway romthelnd|aGate,oneo New De|h|s|andmarks, and cont|nuedbor|ngbeneaththegovernment 199 www.masterbu||der.co.|nTheMasterbu||der -March2012Workers|n thetunne|be|ow thecap|ta|, New De|h|, work|ngtowardthecomp|et|on o the2ndPhaseo the New De|h|MetroExtens|on Pro|ectOFTAassemb|y s|te. lttookamere4monthstocomp|etetheassemb|yTunne|Eng|neern|gTBMs Tunne|Eng|neern|gTBMsd|str|ctw|th |tsembass|esw|thout prob|ems. The10TBMssuccessu||ycomp|etedtunne|||ngw|th the|ast breakthrough occurr|ng|n October2009, wh|ch a||owstoopen thenewmetro||nestotra|c |n duet|mebeore theCommonwea|thGames.Phasello theNew De|h|Metro Extens|on Pro|ect|nvo|vedmu|t|p|esot groundtunne|stobeboredby Pobb|ns Earth PressureBa|anceMach|nes (EPBMs) between underground stat|ons excavated by cut and cover. The tunne|s rangedrom8.6 14.0m(28 46t) be|owthewater tab|e|n sandy s||t, s||ty sand andgrave|s. Both EPBcutterheads eatureda55%open|ngrat|otoa||ow a smooth |ow o muckandtoavo|d c|ogg|ng the cutterhead. The mach|nes usedsevera|typeso tungsten carb|de b|ts or bor|ng |n sot but abras|ve ground andshat-typescrew conveyorsto removewater-bear|ngmuck. Con-t|nuous|y erected ||n|ng a|ong the |engtho thetunne|cons|stedo re|norced concretesegments275mm(11|n) th|ck.SleemanabadCarrier TunnelTheS|eemanabadCarr|er Cana||s parto thelnd|an GovernmentsBarg| D|vers|on Pro|ect, wh|ch w||| source waterromtheNarmadaP|ver to|rr|gate 250,000acres(100,000hectares)o|and. Thecontractor, a|o|ntventureoM/sPate|Eng|neer|ng,SEWand Coasta|Pro|ectsL|m|ted(CPL), s|gned acontractw|th Pobb|nsor thesupp|yo a10.0m(32.8t)d|ameter EPB, as we||astheback-up system, cutt|ng too|s, sparesandcont|nuousconveyorsystem. CPL a|sooptedor Ons|teF|rst T|meAssemb|y (OFTA)o themach|ne atthe|obs|te, |n order toexped|tethe pro|ectschedu|e. ThePobb|nshybr|d mach|ne|sau||y unct|ona|hardrock S|ng|eSh|e|dandsotgroundEPB TBM, des|gnedor |ongsect|onso 180 MPa(26,000ps|)CS |o|ntedrockand marb|e, |nterspersedw|th c|ay and grave|. ln sect|onso sotground, the mach|ne runs as a standard, pressur|zed EPBw|th an abras|on-res|stant, shat-typescrew conveyor. Whenshort sect|onso rockor m|xedgroundare encountered, themach|necan berun|n non-pressur|zedEPBmode. ln |ongersect|onso rock, theTBM can be convertedtoahardrockS|ng|eSh|e|d setupby sw|tch|ngout thescrewconveyorw|th abe|tconveyor. Thehybr|dEPB wascomp|etedus|ngOns|teF|rstT|me Assemb|y (OFTA)|n MadhyaPradesh,lnd|aonMarch14, 2011.EastWestGasPipeline(TunnelLength:100m;Diameter:1524m)Thep|pe||ne|sp|annedtotranser30b||||on cub|c meterso gasromthe gas|e|dso lnd|aseast coast (Kak|nada,AndhraPradesh)tothere|ner|es |ocated|n thewest(Ahmedabad,Gu|arat). TwoHerrenknechtHardPock S|ng|eSh|e|dTBMswereuseds|nce 2006dur|ngtheconstruct|on o the p|pe||ne. Themach|nescrossedroads andra||way tracksa|ongthe|r tunne| route. W|th m|n|mumcoverso on|y 1.5 meters 60-|nch stee| p|pes were pushed through theundergroundus|ngthe p|pe |ack|ng method. The two mach|nes M-1118MandM-1120Mw|th hardrock cutterheadsande|ectr|c dr|veswere opt|ma||y equ|ppedor operat|ng|n the hardandpart|a||y br|tt|erockorma-t|ons. Thesystemor thetransportotheexcavatedmater|a|wasqu|ck|yoperat|ona|compr|s|ngbe|tconveyors,mucksk|psandw|nches.Ghatkopar HighLevel TunnelThepro|ectcompr|sesa2.6-km |ongtrench|esstunne|.Tunne|||ng cha||enges|nc|udemass|veand weatheredbasa|taswe||asthe groundwater |eve|a|ongthetunne| a||gnment. A Herrenknecht TBM2500XH,equ|ppedw|th 21d|scs, |sdep|oyedto crackthebasa|t. Theta||sea|o the 200TheMasterbu||der -March2012 www.masterbu||der.co.|n"We have exciting planstoexpand our investmentinndia to meetthe demand inndia'sboominginfrastructure market.KazuhiroFukumotoGenera|Manager, Saka|Factory, H|tach|ZosenPobb|ns|swork|ngw|th |eadlnd|aconstruct|on company Ja|prakash toensuresuccesso the|ongest,|argestd|ameter, hardrockTBM tunne||n lnd|ash|story andc|a|medby Pobb|nsasthe|ongest|n thewor|d w|thout|ntermed|ateaccesspo|nts.Tunne|Eng|neern|gTBMs Tunne|Eng|neern|gTBMsHerrenknechtHardPockTBM useddur|ngthe2006construct|on o theEast-Westgasp|pe||neTBMavo|dsgroundwater|ngress dur|ngr|ng|nsta||at|on. Water |ngress through thecutt|ngwhee|othe m|cromach|ne|spumpedout.Varavalli ReservoirTwoGr|pper TBMsw|th ad|ametero 3,000mmdrovesevera|reshwatertunne|s|nMumba|snortheastern suburbs. S|ncerockstrengthso up to 250MPahadtobemastereda|ongthe overa||9.7k||ometer-|ongtunne| sect|ons, twoHerrenknechtGr|pperTBMswereused. W|th d|ameterso 3.0 and2.8meters, they arethesma||est Gr|pper TBMsever des|gnedand manuacturedby Herrenknecht.BangaloreMetroTwo6.44d|ameter H|tach|ZosenS|urry Tunne|Bor|ngMach|ne(TBM) wereusedor th|stunne||ngpro|ect.Thetunne||nggeo|og|ca|pro||ewasa m|xtureo so||andbedrock, wh|chrequ|redaS|urry Typeo TBMmach|ne equ|ppedw|th 1200kWcutter head dr|vepower, aF|rstmach|neo th|stype |nlnd|a, tomeetsuchcha||enge.KishangangaHydroelectricProjectThetunne||nggeo|og|ca|pro||e wasam|xtureo basa|t, andes|te,gran|te/granod|or|te. SELl was |nvo|ved |n thesupp|y o anew Doub|eSh|e|d n|versa|TBM, back-up systemand aux|||aryequ|pment(ro|||ngstock, vent||at|on system, sparepartsetc.).Thepro|ect|nvo|vedexcavat|on o the HeadraceTunne|o 14,630mbydoub|esh|e|dTBM hav|ngbor|ng d|ameter o 6,10m, |nterna||n|shed d|ameter 5,20m. Tunne|||n|ngw|thconcretesegments.FutureOutlookTheTBM |ndustry |ssub|ecttoa cont|nuous|mprovementprocessw|ththeuturetrend|ngtowards|argertunne|pro||es, |ongtunne|dr|ves,tunne|satgreater depthsandw|th h|ghgroundwater pressures, wh|ch have|nthepastnotbeen ser|ous|y cons|dered eas|b|e. Demand|ngpro|ectrequ|re-mentsunder grue||ngcond|t|onsand |nnovat|ve|deaso contractorsand p|anners are dr|v|ng urther techno|og|ca| deve|opment|nTBMtechno|ogy. lmprovedsaety requ|rementsand comprehens|ver|skmanagementare a|sop|ay|ngan |ncreas|ng|y |mportant ro|eor a||part|es|nvo|ved|n thedes|gnandexecut|on o construct|on pro|ects w|th todays tunne|s are pass|ng beneathdense|y-popu|atedareas, mounta|n rangesor r|versandestuar|es.PictureSourcewww.robb|nstbm.com, AP / Keystone/ Batzar|n|www.skyscraper.ta|kwhat.comwww.herrenknecht.com202TheMasterbu||der -March2012 www.masterbu||der.co.|nTunne|Eng|neern|gTBMs Tunne|Eng|neern|gTBMs