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毕业设计文献翻译
本科毕业设计(论文)
外文翻译
题目
某大学科技楼结构设计及基坑支护
学院
建工学院
专 业
土木工程
班 级
学 号
学生姓名
指导教师
教务处制
外文资料来源及题目(原文附后)。
1.资料来源:
指导老师给题
2.题目:
DesignChartsforPilesSupportingEmbankmentsonSoftClay
3.作者:
H.G.Poulos,F.ASCE
译成中文后题目(译文附后)
软土地基上桩承式路堤的设计图表
指导教师审阅意见:
签名:
年月日
DesignChartsforPilesSupportingEmbankmentsonSoftClay
H.G.Poulos,F.ASCE
Abstract:
Thispaperdescribesthedevelopmentandapplicationofdesignchartsforpiledembankmentdesigns.Itoutlinesthecomputationalapproachadopted,thegeotechnicalprofilesused,andtheapplicationofthedesignprocedureusingthecharts.ThesoilprofileusedforthechartsisrepresentativeofaMalaysiansoftclayprofile,involvingamoreorlessnormallyconsolidatedsoil,withastrengthandstiffnessthatvarieslinearlywithdepth.SuchaprofileistypicalofthegroundconditionsinavarietyofcountriesintheSoutheastAsianregion.Thedesignchartsaddresstheissuesofpilecapacity,settlementduetoembankmentload,settlementduetoatemporarypilingconstructionplatform,andlateralresponseofpilesneartheedgeoftheembankment.Thechartsconsidervariationsingroundconditions,embankmentheight,pilelength,andpilespacing.Anillustrativeexampleisgiventodemonstratetheuseofthecharts.
CEDatabasesubjectheadings:
Embankments;Foundationdesign;Lateraldisplacement;Pilefoundations;Settlement;Soilsettlement;Clays;Softsoils.
Introduction
Piledembankmentsprovideapossiblesolutionfortheconstructionofroadsandtransportcorridorsoversoftsoils.Theyhavetheadvantageofbeingrelativelyrapidtoconstructanddonotrequiretheextendedtimeperiodsthatmanyconventionalformsofgroundimprovementdemand(e.g.,preloading).Piledembankmentshavebeenusedincreasinglyinanumberofregions,includingEurope,SoutheastAsia,andAustralasia.Avarietyofmethodsofdesignhavedeveloped,rangingfromrelativelysimplisticapproaches(forexample,BritishStandardsInstitution1995)torelativelysophisticatedmethodsinvolvingadvancednumericalanalysis(e.g.,RussellandPierpoint1997;Kemptonetal.1998;Hsi2001;HanandGabr2002;Wong2002).Themajorityofthesimplermethodsaddressonlythestabilityorultimatelimitstate,orelsefocusontheissueofloadsharingandarchingbetweenthepilesandtheground(e.g.,TingandToh1983;HewlettandRandolph1988;Lowetal.1994).
Thesimplerdesignmethodscurrentlyavailablegivelittleornoconsiderationtosettlementsanddeformations.Inmanycases,suchdeformationsmayhaveaprofoundinfluenceonthelongtermperformanceoftheembankment,anddesigncriteriafrequentlyspecifyupperlimitstothevaluesofsettlementanddifferentialsettlementthatcanbetolerated.Whileadvancednumericalanalysesmaybeappropriateandnecessaryfordetaileddesign,theyaregenerallynotsuitedtoarapidassessmentofthefeasibilityofpiledembankmentconstructionforaparticularsite.Tofacilitatepreliminaryassessmentanddesignofpiledembankments,aseriesofdesignchartshasbeendeveloped.Thechartsconsidervariationsingroundconditions,embankmentheights,andpiletypes.Forsimplicity,aperfectlyflexibleembankmenthasbeenassumed.Considerationisalsogiventotheeffectsofsoilmovementsarisingfromtheconstructionofatemporarypilingplatformfill(typically1to1.5mthick).
ThesoilprofileusedforthechartsisrepresentativeofaMalaysiansoftclayprofile,involvingamoreorlessnormallyconsolidatedsoil,withastrengthandstiffnessthatvarieslinearlywithdepth.SuchaprofileistypicalofthegroundconditionsinavarietyofcountriesintheSoutheastAsianregion.
Thispaperdescribesthedevelopmentandapplicationofthedesignchartsforpiledembankmentdesigns.Itoutlinesthecomputationalapproachadopted,thegeotechnicalprofilesused,andtheapplicationofthedesignprocedureusingthecharts.Illustrativeexamplesaregiventodemonstratetheuseofthecharts.
GeotechnicalModel
AconsiderableamountofinformationonthegeotechnicalcharacteristicsofsoftmarineclaydepositsinMalaysiaisavailable(e.g.,Ramlietal.1994;RamliandIsmael,personalcommunication,1992;SagaeandGoh1997;Tanetal.2004).Thereisanindicationthat,belowasurfacedesiccatedcrust2–3mthick,theclaysaremoreorlessnormallyconsolidatedandhaveanundrainedshearstrengththatincreaseslinearlywithdepth.Onthebasisoftheavailabledata,therelationshipchosenforthepresentstudyisrepresentedbytherelationship
su=10+1.5zkPa
(1)
wherez=depthbelowthesoilsurface(m).
ThisrelationshipisperhapsmoreconservativethanthatsuggestedbyRamlietal.(1994)andistowardsthelowerendoftherangeofvaluesgivenbyTanetal.(2004),butappearstobeareasonable(albeitconservative)fittothedata.
Fortheestimationofsettlementsduetosurfaceloadings,datafromtheavailablereferenceswasexamined,andvaluesadoptedforthecompressionratio[Cc/(1+e0)]intheupper15mwere0.30forthenormallyconsolidatedstateand0.05fortheoverconsolidatedstate.Below15m,thecompressionratiowastakentobe0.15forthenormallyconsolidatedstateand0.025fortheoverconsolidatedstate.Itisunderstoodthatthelowercompressionratiobelow15mmaybeaconsequenceofthissoilhavingalowerwatercontent,plasticityindex,andliquidityindexthanthesoilaboveit.Theupper5mwasassumedtobeoverconsolidated,withtheremainderofthesoilprofilebeingnormallyconsolidated.
Fortheestimationofpilesettlements,itwasassumedthattheembankmentpileswouldbedriven,andaccountwastakenoftheeffectsofpileinstallationinstiffeningthesoilaroundthedrivenpiles.BasedoncorrelationsdevelopedbyPoulos(1972D)forsoftclays,adrainedYoung’smodulusofthesoilaroundthepileof300suwasadoptedforthedesigncharts.Considerationisgivenhereonlytothelong-termsettlementsoftheembankment,whichincludebothundrainedandconsolidationcomponents,butexcludinganylong-termcreepsettlements.
Forestimationofpilecapacity,theultimateskinfrictionwasrelatedtotheundrainedshearstrengthviatheadhesionfactorα,whichisitselfafunctionofsu(Tomlinson1986).Thevalueofαwastypicallywithintherange0.9–1.0.Theultimatebaseresistancewastakenas9sub,wheresub=undrainedshearstrengthinthevicinityofthepiletip.
Forthepurposesofthedesigncharts,thebasicvalueofthetotalthicknessofthesoftclaylayerwastakentobe40m,buttheeffectsofshallowerlayerdepthswerealsoinvestigatedandexpressedintermsofcorrectionfactorstotheresultsforthe40-mlayerdepth.Underlyingthesoftclayisalayerofstiffclay,whosepropertieswereassessedfromdatapresentedbyRamlietal.(1994).Itisrecognizedthatthechosensoilprofileisratherspecificandthattheinfluenceofsuchimportantfactorsasstresshistory,stratigraphy,andsoilpropertiesarenotincorporatedintothisstudy.Nevertheless,itisfeltthatthechartsmayprovideareasonableindicationofthedesignrequirementsforpilessupportingembankmentsonrelativelythickdepositsofclaythatareessentiallynormallyconsolidated.
Fig.1summarizesthegeotechnicalmodeladoptedforthedevelopmentofthedesigncharts.
Fig.1.Assumedgeotechnicalprofile
DevelopmentofDesignCharts
Thedesignofpilesforpiledembankmentsrequiresconsiderationofatleastfourissues:
•Geotechnicalcapacityofthepiles;
•Settlementofthepiles;
•Lateralresponseofthepiles;and
•Structuralcapacityofthepiles.
Forthepurposesofdevelopingdesigncharts,attentionhereisfocusedonthefirsttwoissues,butsomeconsiderationisalsogiventotheothertwo.Ifthepileheadsareproperlyattachedtoaslabormattress,thenlateralpiledeflectionsshouldnotbeaconcernunlessgroundmovementsaregeneratedbysomeotheractivityadjacenttothepiles,e.g.,fillingorexcavation.Sucheffectsareexaminedinthispaper.Theaxialforcesforstructuraldesignofthepilesshouldincludeboththosearisingfromtheappliedloadingandthedowndragforcesdevelopedbygroundmovementsduetotheplacementoffillforapilingplatform.Considerationisalsogiventothesedowndragforceshere.
AnalysisProcedure
Themainanalyseswerecarriedouttoobtainthreeaspectsofthebehaviorofembankmentpiles:
1.Theaxialload-settlementbehavior,includingtheultimateaxialloadcapacityandthesinglepileheadstiffness;
2.Theeffectofgroupinteractiononpileheadstiffness;and
3.Theeffectonthepilesofverticalgroundmovementsinducedbytheconstructionofthefillforthepilingplatform(thepossibleeffectsoflateralgroundmovementswerenotconsidered).
Fortheseanalyses,twocomputerprogramswereused:
PIES(forItems1and3above)andDEFPIG(forItem2).BothprogramsweredevelopedattheUniversityofSydney,Australia.
PIEScomputestheaxialmovementandloaddistributionwithinapilesubjectedtoaxialloadand/orexternallyimposedverticalsoilmovements.Theprogramusesasimplifiedboundaryelementformulation,andthesoilcanberepresentedeitherbyanelasticcontinuumoraseriesofsprings.Ineachcase,nonlinearresponseoftheinterfacecanbeincorporatedbyassuminganelastic-plasticorhyperbolicrelationshipbetweensoilstiffnessandstresslevel,andbyallowingfortheeffectsofpile-soilslipandbasebearingfailurebyspecifyinglimitingvaluesofshaftresistanceandend-bearingresistance.
DEFPIGisaprogramforcalculatingthedeformationsandloaddistributionwithinagroupofpilessubjectedtovertical,horizontal,andmomentloading.Theprogramconsiders