地下室设计深基坑中英文对照外文翻译文献

中英文对照外文翻译(文档含英文原文和中文翻译)DeepExcavationsABSTRACT：Allmajortopicsinthedesignofin-situretainingsystemsfordeepexcavationsinurbanareasareoutlined.Typeofwall,waterrelatedproblemsandwaterpressures,lateralearthpressures,typeofsupport,solutiontoearthretainingwalls,typesoffailure,internalandexternalstabilityproblems.KEYWORDS:deepexcavation;retainingwall;earthpressure;INTRODUCTIONNumbersofdeepexcavationpitsincitycentersareincreasingeveryyear.Buildings,streetssurroundingexcavationlocationsanddesignofverydeepbasementsmakeexcavationsformidableprojects.Thischapterhasbeenorganizedinsuchawaythatsubjectsrelatedtodeepexcavationprojectsaresummarizedinseveralsectionsintheorderofdesignroutine.Thesearetypesofin-situwalls,waterpressuresandwaterrelatedproblems.Earthpressuresincohesionlessandcohesivesoilsarepresentedintwodifferentcategories.Groundanchors,strutsandnailsassupportingelementsareexplained.Anchorsaregivenmoreemphasiscomparedtoothersduetowidespreaduseobservedintherecentyears.Stabilityofretainingsystemsarediscussedasinternalandexternalstability.Solutionofwallsforshears,moments,displacementsandsupportreactionsunderearthandwaterpressuresareobtainedmakinguseofdifferentmethodsofanalysis.Apilewallsupportedbyanchorsissolvedbythreemethodsandtheresultsarecompared.Typeofwallfailures,observedwallmovementsandinstrumentationofdeepexcavationprojectsaresummarized.TYPESOFEARTHRETAININGWALLS1.1IntroductionMorethanseveraltypesofin-situwallsareusedtosupportexcavations.Thecriteriafortheselectionoftypeofwallaresizeofexcavation,groundconditions,groundwaterlevel,verticalandhorizontaldisplacementsofadjacentgroundandlimitationsofvariousstructures,availabilityofconstruction,cost,speedofworkandothers.Oneofthemaindecisionsisthewater-tightnessofwall.Thefollowingtypesofin-situwallswillbesummarizedbelow;Bracedwalls,soldierpileandlaggingwallsSheet-pilingorsheetpilewallsPilewalls(contiguous,secant)DiaphragmwallsorslurrytrenchwallsReinforcedconcrete(cast-in-situorprefabricated)retainingwallsSoilnailwallsCofferdamsJet-groutanddeepmixedwallsTop-downconstructionPartialexcavationorislandmethod1.1.1BracedWallsExcavationproceedsstepbystepafterplacementofsoldierpilesorsocalledkingpostsaroundtheexcavationatabout2to3mintervals.ThesemaybesteelH,IorWFsections.Railsectionsandtimberarealsoused.Ateachlevelhorizontalwalingbeamsandsupportingelements(struts,anchors,nails)areconstructed.Soldierpilesaredrivenorcommonlyplacedinboredholesinurbanareas,andtimberlaggingisplacedbetweensoldierpilesduringtheexcavation.Variousdetailsofplacementoflaggingareavailable,however,precastunits,in-situconcreteorshotcretemayalsobeusedasalternativetotimber.Dependingongroundconditionsnolaggingmaybeprovidedinrelativelyshallowpits.Historicallybracedwallsarestrutsupported.Theyhadbeenusedextensivelybeforethegroundanchortechnologywasdevelopedin1970s.Soilswithsomecohesionandwithoutwatertableareusuallysuitableforthistypeofconstructionordewateringisaccompaniedifrequiredandallowed.Strutsupportiscommonlypreferredinnarrowexcavationsforpipelayingorsimilarworksbutalsousedindeepandlargeexcavations(SeeFig1.1).Groundanchorsupportisincreasinglyusedandpreferreduetoaccessforconstructionworksandmachinery.Walingbeamsmaybeusedoranchorsmaybeplaceddirectlyonsoldierpileswithoutanybeams.1.1.2Sheet-pilingorSheetPileWallsSheetpileisathinsteelsection(7-30mmthick)400-500mmwide.ItismanufacturedindifferentlengthsandshapeslikeU,Zandstraightlinesections(Fig.1.2).Thereareinterlockingwatertightgroovesatthesides,antheyaredrivenintosoilbyhammeringorvibrating.Theiruseisoftenrestrictedinurbanizedareasduetoenvironmentalproblemslikenoiseandvibrations.Newgenerationhammersgenerateminimumvibrationanddisturbance,andstaticpushingofsectionshavebeenrecentlypossible.Insoftgroundseveralsectionsmaybedrivenusingatemplate.Theproductendisawatertightsteelwallinsoil.Oneside(inner)ofwallisexcavatedstepbystepandsupportisgivenbystrutsoranchor.Walingbeams(walers)arefrequentlyused.Theyareusuallyconstructedinwaterbearingsoils.Steelsheetpilesarethemostcommonbutsometimesreinforcedconcreteprecastsheetpilesectionsarepreferredinsoftsoilsifdrivingdifficultiesarenotexpected.Steelpilesmayalsoencounterdrivingdifficultiesinverydense,stiffsoilsorinsoilswithboulders.Jettingmaybeaccompaniedduringtheprocesstoeasepenetration.Stepilesectionslsheetusedinsuchdifficultdrivingconditionsareselectedaccordingtothedrivingresistanceratherthanthedesignmomentsintheproject.Anotherfrequentlyfacedproblemistheflawsininterlockingduringdrivingwhichresultinleakagesunderwatertable.Sheetpilewallsarecommonlyusedfortemporarypurposesbutpermanentcasesarealsoabundant.Intemporaryworkssectionsareextractedaftertheirserviceisover,andtheyarereusedaftermaintenance.Thisprocessmaynotbesuitableindenseurbanenvironment.1.1.3PileWallsIn-situpileretainingwallsareverypopularduetotheiravailabilityandpracticability.Therearedifferenttypesofpilewalls(Fig.1.3).Incontiguous(intermittent)boredpileconstruction,spacingbetweenthepilesisgreatthanthediameterofpiles.Spacingisdecidedbasedontypeofsoilandlevelofdesignmomentsbutitshouldnotbetoolarge,otherwisepiecesoflumpsetc.dropandextraprecautionsareneeded.Cohesivesoilsorsoilshavingsomecohesionaresuitable.Nowatertableshouldbepresent.Acceptableamountofwateriscollectedatthebaseandpumpedout.Commondiametersare0.60,0.80,1.00m.Walingbeams(usuallycalled„breastingbeams)areTangentpileswithgroutinginbetweenareusedwhensecantpilingordiaphragmwallingequipmentisnotavailable(i.e.incaseswheregroundwaterexists).Poorworkmanshipcreatessignificantproblems.Secantboredpilewallsareformedbykeepingspacingofpileslessthandiameter(S<D).Itisawatertightwallandmaybemoreeconomicalcomparedtodiaphragmwallinsmalltomediumscaleexcavationsduetocostofsiteoperationsandbentoniteplant.Thereisalsoneedforplacefortheplant.Itmaybeconstructed“hardhard”aswellas“soft-hard”.“Soft”concretepilecontainslowcementcontentandsomebentonite.Primaryunreinforcedpilesareconstructedfirstandthenreinforcedsecondarypilesareformedbycuttingtheprimarypiles.Pileconstructionmethodsmayvaryindifferentcountriesforalltypeofpilewallslikefullcasingsupport,bentonitesupport,continuousflightauger(CFA)etc.mostlyreinforcedconcretebutsheetpilesectionsorsteelbeamsarealsoused.1.1.4DiaphragmWallsDiaphragmwallprovidesstructuralsupportandwatertightness.Itisaclassicaltechniqueformanydeepexcavationprojects,largecivilengineeringworks,undergroundcarparks,metropitsetc.especiallyunderwatertable.Thesereinforcedconcretediaphragm(continuous)wallsarealsocalledslurrytrenchwallsduetothereferencegiventotheconstructiontechniquewhereexcavationofwallismadepossiblebyfillingandkeepingthewallcavityfullwithbentonite-watermixtureduringexcavationtopreventcollapseoftheexcavatedverticalsurfaces.Wallthicknessvariesbetween0.50mand1.50m.Thewallisconstructedpanelbypanelinfulldepth.Panellengthsare2mto10m.Shortlengths(2-2.5m)areselectedinunstablesoilsorunderveryhighsurcharges.Nowadaysdepthofpanelswaterstopsexceeded100m,excavationdepthsexceeded50m.DifferentpanelshapesotherthantheconventionalstraightsectionlikeT,L,H,Y,+arepossiblusedtoformandforspecialpurposes.Panelexcavationismadebycableorkellysupportedbucketsandbyarecentdesigncalled„cutteror„hydrofraisewhichisapairofhydraulicallyoperatedrotatingdisksprovidedwithhardcuttingtools.Excavationinrockispossible.Slurrywalltechniqueisaspecializedtechniqueandapartfromthebucketortheframecarryingthecutterequipmentlikecrawlercrane,pumps,tanks,desandingequipment,airlifts,screens,cyclones,silos,mixers,extractorareneeded.Tremieconcreteisplacedintheslurrystartingfromthebottomafterlowreinforcementringcages.Jointbetweenthepanelsisasignificantdetailinwaterbearingsoilsandsteelpipe,H-beamorwaterstopsareused.1.1.5ReinforcedConcreteRetainingWallsExcavationinStagesItisacommontypeofstagedexcavationwallusuallysupportedbygroundanchors.Soilswithsomecohesionaresuitablebecauseeachstageisfirstexcavatedbforeformworkandconcreteplacement.Nowatertableorappreciableamountofwatershouldbepresent.Sometimesmicropilesupportisgivenifrequiredduetoexpectedcave-ins.1.1.6SoilNailWallsSimilartothemethodaboveexcavationismadestepbystep(1.5to2mhigh).Shotcreteiscommonforfacingandwiremeshisused.Softfacingisalsopossiblemakinguseofgeotextiles.Holeisdrilled,ordinarysteelbarsarelowered,andgroutisplacedwithoutanypressure.Soilshouldbesomewhatcohesiveandnowatertableorsignificantwaterflowshouldbepresent.1.1.7CofferdamsCofferdamisatemporaryearthretainingstructuretobeabletomakeexcavationforconstructionactivities.Itisusuallypreferredinthecoastalandseaenvironmentlikebridgepiersandabutmentsinrivers,lakesetc.,wharves,quaywalls,docks,breakwatersandotherstructuresforshoreprotection,largewaterfrontstructuressuchaspumphouses,subjectedtoheavyverticalandhorizontalloads.Sheetpilingiscommonlyusedinvariousformsotherthanconventionalwallslikecircularcellularbodiesordoublewallsconnectedinsideandfilledwithsand.Stabilityismaintainedbysheetingdrivendeeperthanbase,sandbodybetweensheetingandinsidetierods.Earthembankmentsandconcretebodiesarealsoused.Contiguous,tangent,secantpilesordiaphragmwallsareconstructedincircularshapes,andnointernalbracingoranchoringisusedtoformacofferdam.Reinforcedconcretewalingbeamssupportbyarching.Shaftsarealsomadewiththismethod.Largeexcavationsorprojectdetailsmayrequireadditionalateralsupport.1.1.8JetGroutandDeepMixedWallsRetainingwallsaremadebysingletotriplerowofjetgroutcolumnsordeepmixedcolumns.Thereisasoilmixedwall(SMW)techniquespeciallydevelopedforwallconstructionwhereHsectionsareusedforreinforcement.Singlereinforcingbarisplacedinthecentralholeopenedforjetgroutcolumns.Anchors,nailsorstrutsmaybeusedforsupport.1.1.9TopDownConstructionRetainingstructure(generallydiaphragmwall)isdesignedandconstructedaspermanentloadbearingwallsofbasement.Pilesorbarettesaresimilarlyplacedtocompletethestructuralframe.Topslabiscastatthegroundsurfacelevel,andexcavationismadeundertheslabbysmallersizedexcavatorsandcontinuedownforming basementslabsateachlevel.Therearespecialconnectiondetails.Topdownmethodispreferredinhighlypopulatedcitycenterswherehorizontalandverticaldisplacementsareverycritical,andanchorsandstrutsareverydifficulttouseduetocomplexundergroundfacilitiesandlifelinestructuresandsiteoperationsaredifficulttoperform.1.1.10PartialExcavationorIslandMethodItispossibletogivestrutsupporttoretainingwallsatalaterstageafterconstructingcentralsectionsofabuildinginlargesizeexcavations.Corethestructureisbuiltatthecentralpartmakingslopedexcavationsatperipheralareasandthenthecoreframeisusedtogivesupporttowalls(Figure1.9).Itmaybemorepracticalandconstructiontimemaybelesscomparedtoconventionalbracedsystem.Thismethodmaynotbesuitableinsoftandweaksoilsduetostablityanddeformationproblemsduringslopedexcavations.EARTHPRESSURESONIN-SITURETAININGWALLSIntroductionEarthpressuresonin-situretainingwallsareratherdifferentthanthoseonordinaryretainingwallsduetothesupportingelments.Freedisplacementofwallsarenotallowed.Typeofsupportaffectsthedistributiofnearthpressure.Strutloadsweremeasuredinstruttedexcavationsinmanycountriesinthepast,andrecommendationsweregiven.Groundanchortechnologyisrelativelynew,anddataoninstrumentedanchoredwallsfortotallatepressureandforwaterpressurearebeingaccumulated.Earthpressurediagramsonstruttedandanchoredwallsareexpectedtobesomewhatdifferentduetostiffersupportconditionsintheformer.Theoreticalapproacheswillalsobediscussed.EarthPressureDistributionsonWallsTerzaghiandPeck(1967)andPeck(1969)basedonloadmeasurementsonstrutsrecommendthepressuredistributionshowninFigure2.1forcohesionlesssoils.ItisauniformpressureandgivenbyEq.2.1; p=0.65KγH 2.1AtwhereKistheactiveearthpressurecoefficient,Histheheightofwall.Awatertightandwatertableispresent,buoyantunitweightshouldbewatertightandwatertableispresent,buoyantunitweightshouldbeusedunderwatertableandwaterpressureshouldbeadded.Sincebracedexcavationsweregenerallydewateredinthepastprojectstheunitweightintheexpressionwasdescribedaswetorbulk.IfwallTherectangulardiagramproposedinthefigureisnotanactualpressuredistributionbutanenvelopeobtainedbyplottingthemeasuredstrutloadsconvertedtopressuredistributionateachstageofexcavationincludingthefinaldepthcoveringalldistributions.Itisalsocalledapparentpressuredistribution.Itisregardedasaconservativeapproachbecausestrutloadscalculatedbysuchanenvelopearegenerallygreaterthanthemeasuredloads.Rectangularenvelopewithp=0.2γtHisalsorecommendedbyTwineandRoscoe(1996)basedonmorerecentfieldmeasurements.Similarlyuseofsubmergedunitweightbelowwatertableandadditionofwaterpressureisrecommended.Dataoncohesivesoilsareclassifiedforsofttomediumstiffclaysandstiffclay.Anchorornailsupportedwallsmayshowhigherlateraldisplacements,andstressincreasesattheupperlevelsofwallsmaybesomewhatlesscomparedtothedistributionsonstruttedwalls.However,therearenodocumentedcomparisons.Inthesolutionofanchoredwallsbyfiniteelement,boundaryelement,finitedifferencesoftwaresorsimplerspringmodelstheanalysesmayberepeatedwithoutassigningpre-tensionsinitiallylikeincaseofnailsupportedwallsandthenassignthecalculatedreactionsaspretensions.Therearealsorecommendationsonselectionofthetypeofdistributioninrelationtoheightofbracedwalls.Distributionsbasedonpressurecellrecordsarerecommendedforallheightsbutdistributionsbystrutloadmeasurementsarenotfoundsuitableforwallshigherthan15m,theymaybeusedforwallsof10–15mheightdependingonconditionsofthegroundandconstructionandrecommendedforheightslessthan10m.Anothercommoncaseisanalluvialprofilewhereclay,silt,sandlayersmixedindifferentproportionslieindifferentthicknesses.Ifadominantlayerispresentoneoftheabovedistributionsmaybeselected,otherwisetheoreticalapproachlikeCoulomb’searthpressureexpressionmaybefollowedmakinguseofeffectiveparameters,submergedunitweightsandaddedwaterpressure.Effectofdifferentsurchargeloadsonwallsmaybecalculatedbystressdistributionsinelasticmedium(e.g.NAVFAC1982).Fortheupperlimitofveryrigidwallsthedistributionsaredoubled.Widesurchargeloadsmayalsobeconvertedtoequivalentheightsofsoillayer.SUPPORTINGELEMENTSGroundAnchorsIntroductionGroundanchorisacommontypeofsupportingelementusedinthedesignandconstructionofin-situretainingwalls.Itisaninstallationthatiscapableoftransmittinganappliedtensileloadtoaloadbearingstratumwhichmaybeasoilorrock.Asummaryaboutgroundanchorswillbegiveninthissection.Types,capacity,design,constructionandqualitycontrolwillbereviewed.TypesandCapacityofAnchorsTemporaryanchorandpermanentanchorarethemaintypesandasthenamesimplytheformerisusedintemporaryworksandusuallyaperiodofmaximumtwoyearsareassignedasthedesignlife.Designlifeofapermanentanchoristhesameasthelifeofstructure.Corrosionprotectiondetailsandfactorsofsafetyarethemaindifferencesbetweenthetwotypes.Freelengthisafunctionofheightofthewall.Fixedlengthisselectedaccordingtotypeofsoilanditvariesbetween3mand10m.Fixedlengthisthetensileloadbearingpartofananchorinsoil.Therearedifferentmechanismsofstresstransferfromthefixedanchorzonetosurroundingground.Itisusuallyreferencedas„bondstressanddependsonsoiltypeandgroutingprocedure.Exceptingspecialconstructionsinfixedpartofanchorslikeunderreamsinstiffclays,jetgroutedbodiesorinflatedaluminumbags,mostcommontypeofconstructioniscement(andwater)groutwithsomeadditives.Verystiff,hardsoilsandromanchettecksmaybegroutedwithoutpressure.Manysoilsmaybegroutedbutgroutingpressure,watercementratio(w/c)andadditivesplaymajorroledependingonthepermeabilityandstiffnessofthesoil.Fixedlengthofanchorenlargesindiameterwithincreasinggroutpressure.Groutpermeatesorfracturesorpushesthesoilarounddependingontypeofsoil,groutandpressurelevel.Coarseandfinegrainedgranularsoils,alluvialsoilsandweakrocksaregenerallygroutedwithseveralbarsofpressurethroughcasingorusingpacker.Stiffcohesivesoilsandfinecohesionlesssoilsmaybegroutedathigherpressures(greaterthan15-20bars)toformhighlyfracturedlargerfixedendbodiestoobtainhighercapacities.Post-groutingtechniquesthroughtubeandmanchette(sleevetubing)ordouble/tripletubingareused.Mainpossibilitinesfailureofasingleanchorarefailureofground/groutinterface,tendonitselforgrout/tendoninterface.Capacityofanchorsincohesionlesssoilsdependsonaveragegrainsize(D50),uniformitycoefficient(CU),relativedensity(RD),diameterofdrillhole,methodofgroutinjection(primary/secondary)andgroutpressure.HigherD50,CU,RDandgroutpressuresultinhighercapacities.Fixedlengthsof4to8mareinuseand6mseemstobealowerlimitofrecommendationforfinetomediumsands,andthelowerlimitmaybelessforgravellysoils.Permeabilityandgroutcharacteristics(i.e.water-cementratio,pressure)arekeyfactorsforcapacities.Atlowerpressurelevels(lessthan1MPa)andhigherpressures(morethan2MPa)capacitiesfrom400/500to1400/1700kNareobservedinfinetomediumsandsanddensecoarsersandsandgravelsrespectively.Thiswiderangeisduetoenlargementofthedrillholeandmoregroutintrusionincoarsersoils.Calculationsbysoilmechanicsprinciplescannotexplainthesecapacities.Bestwayistoperformtestsondesignanchors.Loadcapacityofanchorsinclaysislowcomparedtosandyandgravellysoils.Fixedanchorlengthsindesignareusually7-8m.Applicationoflowgroutingpressure(lessthan1MPa)anduseofcasingtubesmaybebeneficialtothecapacity.Casingtubesalsopreventformationofremoldedsoftcohesivefilmonboreholesurfaceinlayeredsoilswhichreducescapacitysignificantly.Capacityofanchorscanbeincreasedinstifffissuredclaysusinghighpressuregroutingandpost-grouting.Highpressurecauseshydrofracturingand/orpenetrationofgroutintoexistingfissures.Usingbellsorunder-reamsinthefixedanchorzoneinstifferclays(cU>90kPa)alsoincreasescapacity.Tremiegroutedstraightshaftsinverystifforhardsoilsyieldsufficientcapacitiesimilartoanchorsinrock.Skinfriction(m)increaseswithdecreasingplasticityandincreasingconsistency((wL-w)/IP)mrangeisfrom50tomorethan400kPainstiffclays.Pressuregroutingisalsousedinrock.SkinfrictionorbondvaluesforvarietyofrockscanbefoundinBS(8081)andotherreferences.Groutisintensionlikethetendon,anditisassumedthatultimatebondstressbetweengroutandtendonisuniform.Forcleanstrandsanddeformedbarsalimitof2MPaisrecommended.Bondstrengthcanbesignificantlyaffectedbythesurfaceconditionofthetendon,particularlywhenlooseandlubricantmaterialsorlooserust,soil,paintarepresentattheinterface.Minimumgroutcompressivestrengthof30MPaisrecommendedpriortostressing.Atgrout/encapsulationinterfacemaximumultimatebondistaken3MPa.Encapsulationsareusuallyusedinpermanentanchorapplicationsagainstcorrosion,andsingleordouble(concentric)corrugatedplasticormetalductscoversingleormulti-unitendonsandgrouted.Detailsathead,freelength,sealbetweenfreeandfixedlengthsandfixedlengthvaryinmanydifferentpatenteddesigns(SeeforexampleFIP,1986).3.1.3PlanningofAnchorsFreelengthateachexcavationstageandfixedlengthareFixedselected.lengthincohesionlessandcohesivesoilshasbeendiscussedintheprevioussection.Itisusuallykeptconstantinaproject.Fixedlengthhastobeplacedoutsidetheactivewedgebehindwall.Itiscustomarytoaddanextratofreelength.Thisisespeciallyusefulinprojectsinstiffclayswheredeformationsatthebackofwallextendtodistancesthreetimesthedepthofexcavation.Minimumspacingofanchorsshouldbe1.5-2mandminimumdistanceof2-3mshouldbeprovidedbetweenthefixedlengths.Ananchordensityof3-8m2/anchorgenerallyobservedinprojectsdependsonfactorssuchaswaterpressure,typeofsoil,depthofexcavationetc.Ifcloselyspacedanchorsareusedeitheradjacentanchorsaredesignedatdifferentangleswiththehorizontallike10°and15°oridenticalrowsarenotused.Anglesbetween5°and25°withthehorizontalarenormallyselectedunlessfixedlengthsarelocatedindeepercompetentlayers.Twoanchorsmaybeplacedatthesameanchorheadatdifferentanglesifrequired.Itisconsideredagoodpracticetodesignpositionsoffixedlengthsinadisorderlymanner.Anotherrecommendationistokeepthewholefixedlengthinasinglelayerinlayeredsoilsifpossible.Distanceoffixedlengthtoanyadjacentfoundation/undergroundserviceisrecommended3mminimum.Spacingofanchorsiscontrolledbytypeofwall,andverticaldistancebetweenrowsisdeterminedbyatrialanderrorprocess(i.e.anchorcapacityvs.spacing,reactionforcesetc.).深基坑工程摘要 本文概述了城市中保留原址的深基础连续墙系统。对墙体，水的相关问题和挡土墙方案，土锚杆的类型和安装进行了阐述。关键词：深基坑，土压力，挡土墙，土锚杆、土锚杆安装综述随着城市中心的采用深基坑作为基础和采用深地下室设计的建筑物和数量逐年增加，使得深基坑工程的施工难度也明显增大。本章以与在原址上的深基坑工程有关的顺序分成几部分行文。对墙体，水压力和水有关的问题类型进行讨论。因为土压力特性在非粘性土和粘性土之间，体现出了两种完全不同的性质。所以锚固，支撑和土钉等支撑系统的出现就是顺理成章的了。近几年来，与其他的方式相比，锚固得到了广泛的使用和推广。挡土墙系统的稳定性可以分为内部和外部的稳定性。对于其受到的剪力、瞬间位移、支撑系统的反作用力、土压力和水压力导致了其使用的分析方法是与地上部分是不同的。也对支撑土钉墙的三种方法的结果进行了比较。 1．挡土墙的种类。 1.1介绍在实际工程应用中，许多不同类型的连续墙被用来做深基坑的支护系统。选用何种类型连续墙的标准是，基坑的尺寸、土质条件、地下水深度、各种不同结构的限制、可施工性、造价、施工速度与其他条件。其中，主要考虑的是墙体的水密性。以下是地下连续墙种类：支撑墙，排桩式地下连续墙板桩墙，井圈护壁墙桩墙地下连续墙阶段性基坑钢筋混凝土挡护墙土钉墙围堰深层喷射搅拌桩逆作法施工局部开挖或筑岛法1.1.1支撑墙当进行到基槽开挖并安放排桩式地下连续墙时，于基槽周围约2到3米间隔内，采用H型、I型钢板或者采用钢丝绑扎固定。并进行围挡。水平或者纵向支撑系统（撑杆，锚栓，钉）也同时进行修建。排桩式地下连续墙经常被广泛应用在城市某些地下存在大面积孔洞的地区，采用木质的排桩时，需要间隔放置在地下连续墙之间。可以采用多种方法安放绑扎的桩。比如采用预制，原址的混凝土或者是木桩进行安放。根据土质情况，可以在相对浅的基槽部分不采用钢筋绑扎。从历史的角度出发，支撑墙系统作为支持系统有久远的历史。在二十世纪七十年代锚固施工工艺出现之前，支撑墙系统广泛应用于各类工程，泥土混合粘性土在地下水位以上的施工在施工条件允许的情况下，经常采用支撑墙系统作为基槽开挖施工的支撑系统。支撑杆支架经常用在施工场地狭窄的管道铺设的基槽开挖或者其他的相类似的情况，同时也用在超深超大的基槽开挖的情况下。随着机械化的发展，土锚杆支撑系统的应用也越来越多。在没有梁结构的约束下，可以直接采用围筒式支护结构或者锚固。1.1.2板桩墙，井圈护壁墙板桩支架是一种薄截面（7-30毫米），400-500毫米直径的钢管支撑系统。可以根据不同的需要制作成U形或者Z型。钢管支架由防水的扣件人工连接安装。由于该施工工艺受到环境因素：如噪音，震动等原因在城市受到限制。随着静压工艺的出现，击锤产生的震动和泥土扰动相比之前的工艺是最小的。施工最后静，压桩在土壤中组成墙体，墙体内侧通过锚固和撑杆组成支撑系统，为开挖的基槽提供支撑。这种工艺经常在含水量高或者软土地区应用。钢管支架是最常使用的，但因其灌入深度与沉降控制较困难，故有时在软土中应用预应力钢管部件较困难。同时，钢板桩支架在密实的土壤、塑性低的土壤或者卵石土里安装困难。此时可采用泥浆喷射安装，通过湿润土壤以减少安装时穿透土层的难度。在类似安装困难的土壤中，钢管桩的安装方案应当由施工方根据实际情况采取办法，而不是在设计时即确定施工方案。另一个经常遇到的问题是在静压钢管施工过程中钢管的连接部分由于暴露在地下水部分导致连接部分漏水。管桩墙经常用于临时目的的支护结构，同时也大量应用于永久工程的项目。在作为临时支护的项目中，该施工方法所用的部件在工程完毕之后是可以回收的，工程的部件通过回收后，通过保养维护可以投入新的工程中，但是在城市密集的建筑中回收部件这一个方法是不明智的，会导致其他建筑物的沉降抑或者会破坏周围建筑物原本稳定的结构。1.1.3桩墙原址桩挡土墙在由于其施工造价经济性优越和可行性高，所以在工程中应用非常广泛。目前桩墙有许多种类。在连续（间歇）钻孔桩施工中，桩之间的间距应该小于桩直径。该间距应基于土壤的种类和设计的深度来确定，但是根据经验，间距不能很大，除了土壤种类和设计的间距外，为了预防大块土壤塌落，也需要其他的预防措施。该施工工艺可以适用于块土、粘结性高的土壤和地下水水位以上的工程，同时在一定范围内的地下水的工程也可以适用，但需要进行排水。该施工工艺桩的直径常见的为0.6米、0.8米和1.0米。横挡系统（常见称谓为“胸撑”）混合泥浆布置在当地下连续墙不适用的情况（换而言之，即地下水存在的情况下）。但是落后的施工工艺会产生很多的问题。钻孔桩墙用于那些空间排放小于直径（S<D）的地方。它本身是一种防水结构的墙。相对于地下连续墙，它在在小型或者中型膨润土基槽开挖的方案中造价明显降低。同样，它们都需要场地来放置施工机械，可以用“硬—硬”或者“软—硬”混凝土来制成。“软”混凝土桩就是一种用低强度混凝土混合粘性土制成。施工时第一段桩无钢筋，切断第一段桩桩头之后接入钢筋桩。桩的施工方法在各国都不同，但基本工序都需要套管支架，膨润土，连续旋翼式螺钻作为施工准备等。除了钢管桩墙之外，大部分的桩墙都需要混凝土作为加强的或者需要用钢肋加强。1.1.4地下连续墙地下连续墙提供了完整连续的支持和防水的功能。地下连续墙尤其在地下水位以下的大型深基坑工程如大型市政建筑，地下停车场等基础开挖的经典做法。因混凝土的性质使制成的地下结构拥有了防水和防坍塌的功能，所以连续墙也称为高强度槽壁。地下连续墙墙体的厚度介于0.5米到1.0米之间。由一道道连续的墙体构成。单个墙体长度由2米到10米不等。短墙体（2-2.5米）经常在不稳定的土壤部分使用。如今，连续墙最深的深度已经达到100米，基槽的开挖宽也度超过50米。不同的情况和使用环境决定了墙体形状的不同，如：T型、L型、H型、Y型和十字型。基槽的壁板通过缆绳、钻杆支撑的筒体或者最新设计的叫做“切割器”或者通过使用一双水力驱动的“水力铰刀”通过操作高强度的削盘工具进行挖掘。如果开挖的基槽在岩石地区也是可行的。泥浆护壁墙技术是一种特殊的区别于套筒或者其他工艺的一种方法。其需要履带起重机、泵、罐清砂装置、、升降机、框架切割装备、钻、搅拌机、风机等装备。开始施工时，把混凝土导管放置在底部，从底部向上浇筑。其中需要重点关注的是饱和水的土壤、钢管，H型梁。1.1.5阶段性基坑钢筋混凝土挡护墙这是一种常见的采用土锚杆固定的阶段性基槽开挖支护手段。因开挖后放入框架和混凝土而适用于无地下水或者施工在地下水平面以上的粘土地区在。该地区适用时，可以采取微型桩支撑以达到期望的防止井壁坍塌的情况。1.1.6土钉墙与上文的阶段性基坑钢筋混凝土挡护墙施工方法相似，需要逐步进行制作（1.5米到2米高）土钉喷网支护经常用喷射混凝土进行表面硬化。除此之外，也可以用松软的土工布进行表面覆盖。当孔洞做好之后，插入钢棒，覆盖上网者或土工织物，然后向其表面进行无压喷射。施工进行到时，土壤出现轻微粘性或者有明显的水流时即完成。1.7围堰围堰是一种临时保持土壤结构使基坑开挖顺利进行的施工活动。它经常使用于海岸或者海洋环境的工程中，例如湖中的桥墩、河堤道路、船坞、防波堤桥墩、或者其他需要进行短时间保护的大型水下结构工程泵站等为了承受巨大的垂直和水平荷载的基础。进行工程时，可使用多种方式，如内部填充沙土的圆形