土木工程毕业论文外文翻译盾构外文原文+中文翻译.docx

土木工程毕业论文外文翻译盾构外文原文+中文翻译.docx

《土木工程毕业论文外文翻译盾构外文原文+中文翻译.docx》由会员分享，可在线阅读，更多相关《土木工程毕业论文外文翻译盾构外文原文+中文翻译.docx（11页珍藏版）》请在冰豆网上搜索。

土木工程毕业论文外文翻译盾构外文原文+中文翻译

毕业设计（论文）外文文献翻译

院系：

土木工程与建筑系

年级专业：

姓名：

学号：

附件：

盾构

SHIELDS

指导老师评语：

指导教师签名：

年月日

SHIELDS

【Abstract】Atunnelshieldisastructuralsystem,usedduringthefaceexcavationprocess.Thepapermainlydiscussestheformandthestructureoftheshield.Propulsionfortheshieldisprovidedbyaseriesofhydraulicjacksinstalledinthetailoftheshieldandtheshieldiswidespreadusedintheundergroundenvironmentwherecannotbeinlongtimestable.Themainenemyoftheshieldisgroundpressure.Non-uniformgroundpressurecausedbythesteeringmayactontheskintendstoforcetheshieldofflineandgrade.Andworkingdecksinsidetheshieldenabletheminerstoexcavatetheface,drillandloadholes.

【Keywords】shieldhydraulicjacksgroundpressuresteeringworkingdecks

Atunnelshieldisastructuralsystem,normallyconstructedofsteel,usedduringthefaceexcavationprocess.Theshieldhasanoutsideconfigurationwhichmatchesthetunnel.Theshieldprovidesprotectionforthemenandequipmentandalsofurnishedinitialgroundsupportuntilstructuralsupportscanbeinstalledwithinthetailsectionoftheshield.Theshieldalsoprovidesareactionbaseforthebreast-boardsystemusedtocontrolfacemovement.Theshieldmayhaveeitheranopenorclosedbottom.Inaclosed-bottomshield,theshieldstructureandskinprovide360-degreegroundcontactandtheweightoftheshieldrestsupontheinvertsectionoftheshieldskin.Theopenshieldhasnobottomsectionandrequiressomeadditionalprovisionisapairofsidedriftsdriveninadvanceofshieldexcavation.Railsorskidtracksareinstalledwithinthesesidedriftstoprovidebearingsupportfortheshield.

Shieldlengthgenerallyvariesfrom1/2to3/4ofthetunneldiameter.Thefrontoftheshieldisgenerallyhoodedtosothatthetopoftheshieldprotrudesforwardfurtherthantheinvertportionwhichprovidesadditionalprotectionforthemenworkingatthefaceandalsoeasepressureonthebreast-boards.Thesteelskinoftheshieldmayvaryfrom1.3to10cminthickness,dependingontheexpectedgroundpressures.Thetypeofsteelusedintheshieldisthesubjectofmanyargumentswithinthetunnelingfraternity.SomeprefermildsteelintheA36categorybecauseofitsductilityandcaseofweldingintheundergroundenvironmentwhereprecisionworkisdifficult.Otherspreferahigh-strengthsteelsuchasT-1becauseofitshigherstrength/weightratio.Shieldweightmayrangefrom5to500tons.MostoftheheaviestshieldsarefoundintheformerSovierUnionbecauseoftheirpreferenceforcast-ironinbothstructuralandskinelements.

Propulsionfortheshieldisprovidedbyaseriesofhydraulicjacksinstalledinthetailoftheshieldthatthrustagainstthelaststeelsetthathasbeeninstalled.Thetotalrequiredthrustwillvarywithskinareaandgroundpressure.Severalshieldshavebeenconstructedwithtotalthrustcapabilitiesinexcessof10000tons.Hydraulicsystemsareusuallyself-contained,air-motorpowered,andmountedontheshield.Workingpressuresinthehydraulicsystemmayrangefrom20-70Mpa.Toresistthethrustoftheshieldjacks,ahorizontalstructuremember（collarbrace）mustbeinstalledoppositeeachjacklocationandbetweentheflangesofthesteelset.Inaddition,somestructuralprovisionmustbemadefortransferringthisthrustloadintothetunnelwalls.Withoutthisprovisionthethrustwillextendthroughthecollarbracestothetunnelportal.

AnEnglishman,MarcBrunel,iscreditedwithinventingtheshield.BrunelsupposedlygothisideabystudyingtheactionoftheTeredonavalis,ahighlydestructivewoodworm,whenhewasworkingattheChathamdockyard.In1818BrunelobtainedanEnglishpatentforhisrectangularshieldwhichwassubsequentlyusestoconstructthefirsttunnelundertheRiverThamesinLondon.In1869thefirstcircularshieldwasdevisedbyBarlowandGreatHeadinLondonandisreferredtoastheGreatHead-typeshield.Laterthatsameyear,BeachinNewYorkCityproducedsimilarshield.Thefirstuseofthecircularshieldcameduring1869whenBarlowandGreatHeademployedtheirdeviceintheconstructionofthe2.1indiameterTowerSubwayundertheRiverThames.Despitethenameofthetunnel,itwasusedonlyforpedestriantraffic.Beachalsoputhiscircularshieldtoworkin1869toconstructademonstrationprojectforaproposedNewYorkCitysubwaysystem.Theprojectconsistedofa2.4mdiametertunnel,90mlong,usedtoexperimentwithasubwaycarpropelledbyairpressure.

Herearesometunnelswhichwerebuiltbyshieldprinciple.

Soft-groundtunnelingSometunnelsaredrivenwhollyormostlythroughsoftmaterial.Inverysoftground,littleornoblastingisnecessarybecausethematerialiseasilyexcavated.

Atfirst,forepolingwastheonlymethodforbuildingtunnelsthroughverysoftground.Forepolesareheavyplanksabout1.5mlongandsharpenedtoapoint.Theywereinsertedoverthetophorizontalbarofthebracingatthefaceofthetunnel.Theforepolesweredrivenintothegroundofthefacewithanoutwardinclination.Afteralltheroofpolesweredrivenforabouthalfoftheirlength,atimberwaslaidacrosstheirexposedendstocounteranystrainontheouterends.Theforepolesthusprovidedanextensionofthetunnelsupport,andthefacewasextendedunderthem.Whentheendsoftheforepoleswerereached,newtimberingsupportwasadded,andtheforepolesweredrivenintothegroundforthenextadvanceofthetunneling.

Theuseofcompressedairsimplifiedworkinginsoftground.Anairlockwasbuilt,thoughwhichmenandequipmentpassed,andsufficientairpressurewasmaintainedatthetunnelfacetoholdthegroundfirmduringexcavationuntiltimberingorothersupportwaserected.

Anotherdevelopmentwastheuseofhydraulicallypoweredshieldsbehindwhichcast-ironorsteelplateswereplacedonthecircumferenceofthetunnels.Theseplatesprovidedsufficientsupportforthetunnelwhiletheworkproceeded,aswellasfullworkingspaceformeninthetunnel.

UnderwatertunnelingThemostdifficulttunnelingisthatundertakenatconsiderabledepthsbelowariverorotherbodyofwater.Insuchcases,waterseepsthroughporousmaterialorcrevices,subjectingtheworkinprogresstothepressureofthewaterabovethetunnelingpath.Whenthetunnelisdriventhroughstiffclay,theflowofwatermaybesmallenoughtoberemovedbypumping.Inmoreporousground,compressedairmustbeusedtoexcludewater.Theamountofairpressurethatisneededincreasesasthedepthofthetunnelincreasesbelowthesurface.

Acircularshieldhasprovedtobemostefficientinresistingthepressureofsoftground,somostshield-driventunnelsarecircular.Theshieldonceconsistedofsteelplatesandanglesupports,withaheavilybraceddiaphragmacrossitsface.Thediaphragmhadanumberofopeningswithdoorssothatworkerscouldexcavatematerialinfrontoftheshield.Inafurtherdevelopment,theshieldwasshovedforwardintothesiltymaterialofariverbed,therebysqueezingdisplacedmaterialthroughthedoorsandintothetunnel,fromwhichthemuckwasremoved.Thecylindricalshelloftheshieldmayextendseveralfeetinfrontofthediaphragmtoprovideacuttingedge.Arearsection,calledthetail,extendsforseveralfeetbehindthebodyoftheshieldtoprotectworkers.Inlargeshields,anerectorarmisusedintherearsideoftheshieldtoplacethemetalsupportsegmentsalongthecircumferenceofthetunnel.

Thepressureagainsttheforwardmotionofashieldmayexceed48.8Mpa.Hydraulicjacksareusedtoovercomethispressureandadvancetheshield,producingapressureofabout245Mpaontheoutsidesurfaceoftheshield.

Shieldscanbesteeredbyvaryingthethrustofthejacksfromleftsidetorightsideorfromtoptobottom,thusvaryingthetunneldirectionleftorrightorupordown.Thejacksshoveagainstthetunnelliningforeachforwardshove.Thecycleofoperationisforwardshove,line,muck,andthenanotherforwardshove.Theshieldusedabout1955onthethirdtubeoftheLincolnTunnelinNewYorkCitywas5.5mlongand9.6mindiameter.Itwasmovedabout81.2cmpershove,permittingthefabricationofa81.2cmsupportringbehindit.

Cast-ironsegmentscommonlyareusedinworkingbehindsuchashield.Theyareerectedandboltedtogetherinashorttimetoprovidestrengthandwatertightness.InthethirdtubeoftheLincolnTunneleachsegmentis2mlong,81.2cmwide,and35.5cmthick,andweighsabout1.5tons.Thesesectionsformaringof14segmentsthatarelinkedtogetherbybolts.Theboltsweretightenedbyhandandthenbymachine.Immediatelyaftertheywereinplace,thesectionsweresealedatthejointstoensurepermanentwatertightness.

Shieldsaremostcommonlyusedingroundconditionwhereadequatestand-uptimedoesnotexist.Theadvantageoftheshieldinthistypeofground,inadditiontotheprotectionaffordedmenandequipment,isthetimeavailabletoinstallsteelribs,linerplates,orprecastconcretesegmentsunderthetailsegmentoftheshieldbeforegroundpressureandmovementbecomeadversefactors.

Oneoftheprincipleproblemsassociatedwithshielduseissteering.Non-uniformgroundpressureactingontheskintendstoforcetheshieldofflineandgrade.Thisproblemisparticularlyacutewithclosedbottomshieldthatdonotrideonrailsorskidtracks.Steeringisaccomplishedbyvaryingthehydraulicpressureinindividualthrustjacks.Iftheshiedistryingtodive,additionalpressureontheinvertjackswillresistthistendency.Itisnotunusualtofindshieldwanderingsev