盾构施工引起土体位移的空间计算方法(2)

图12为距轴线6m土体水平位移计算值与实测结果对比图,各深度水平位移均以地表处水平位移为参照.从图中可以看出计算和实测的最大水平位移发生在隧道中心线深度位置附近,大小为3cm左右,虽然计算得到的最大水平位移比实测大一些,但总体水平位移沿深度的分布趋势与实测一致.总体来说计算结果与实测结果较吻合,说明镜像方法及对注浆过程的计算方法较符合实际情况,计算结果可靠

.

图9

　地表沉降实测值与计算值

图10　地表以下5m沉降实测值与计算值

土体产生位移的主要原因是地层损失,根据地

层损失的空间分布规律采用镜像方法可分析计算隧道推进过程中的位移场分布.将注浆过程看成产生盾尾空隙的逆过程且浆液的空间分布与盾尾空隙的分布相似是一种合理可行的处理方法.

本文采用三维方法对盾构施工进行分析,能分析盾构掘进过程中任意点处X,Y,Z三方向位移,若不关心盾构掘进过程的空间位移分布,

则可 4

图11

　横断面沉降等值线

图12　距隧道中心线6m水平位移实测值与计算值

以简化为平面应变问题,计算量可大为减小.本文

采用的空间镜像方法进一步深化,根据线弹性本构关系还可以由位移场分布求得隧道开挖产生的附加应力分布,进行应力分析.

参

考

文

献

[1]　PeckRB.Deepexcavationsandtunnelinginsoft

ground[A].StateoftheArtReport,Proceedingof7thInternationalConferenceonSoilMechanicsandFoundationEngineering[C].MexicoCity,1969.2252290.

[2]　LeeKM,KerryR,LoKY.Subsidenceowingto

tunnelling..IEstimatingthegapparameter[J].CanadianGeotechnicalJournal,1992,29:9292940.[3]　SagaretaC.Analysisofundrainedsoildeformation

duetogroundloss[J].Geotechnique,1987,37(3):3012320.

[4]　LoganathanN,PoulosHG.Analyticalprediction

fortunneling-inducedgroundmovementsinclays[J].

JournalofGeotechnicalandGeoenviron2mentalEngineering,1998,(9):8462856.

[5]　贾乃文,云天铨.弹性力学[M].广州:华南理工大学

出版社,1990.

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盾构施工引起土体位移的空间计算方法

AccidentAnalysisofPrestressedReinforcedConcreteStructures

DuringConstruction

ZHAOTing2sheng　PANXian2yi　FANGDong2ping

1

2

2

(1.SchoolofCivilEng.&Mechanics,HUST,Wuhan430074,China;2.SchoolofCivilEng.,TsinghuaUniv.,Beijing100084,China)

Abstract:Theprestressedreinforcedconcretestructureduringconstructionisatime2dependentstructuralsystem.

Theloadsactingonthestructureincludeconstructionloadandprestressed

equivalentloads.Becauseoflackingoftheory,theerrorsusuallyappearinthedesignandconstructionofthestructure.Forexample,onerealengineeringisaprestressedreinforcedconcretestructure,andtwosetsofprestressedsteelbararedesigned,onecomesthroughthestripofpostpouringconcreteandtheotherdon’t,moreoverabnormaldeformationisproducedinconstructionofthestructure.Thereforeacontinuumbeamwithelasticseatcomingfromtherestrictofsteelbarinastripofpostpouringconcreteisproposed,consideringtheconstructionloadsandprestressedequivalentloads,furthermorecausesofabnormaldeformationareanalyzed.Theparametersofanchorangleofprestressedsteelbarandstiffnessofelasticseat,etc.arestudied,thenthesuggestionsfordesignandconstructionofprestressedconcretestructureswithastripofpostpouringconcretearegiven.

Keywords:prestressedreinforcedconcretestructures;design;construction;constructionload;

prestressedequivalentloads;deflection

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3-DAnalyticalMethodUsedtoCalculateShieldTunnelingInducedSoilDisplacements

JIANGXin2liang　ZHAOZhi2min

1

1

(1.SchoolofCivilEng.,TianjinUniv.,Tianjin300072,China)

Abstract:Tunnelinginurbanareascausesthemovementofthesoilaroundthetunnel,soestimatingpotentialsoilmovementisveryimportanttocontrolitandprotectexistedconstructionfoundationandundergroundpipelines.Soildisplacementisinducedbygroundlossandisaffectedbyinjectionamount.Accordingtotheregularitiesof32Ddistributionofgroundlossandinjectionamount,usingimagemethodtheory,thenumericalintegratingin32Danalyzingforgroundlossandinjectioninduceddisplacementsduringtunnelingarestudied.

ComparingwiththeobservedresultsofTianjin

undergroundrailwayproject,itisidentifiedtobedependable.

Keywords:imagemethod;groundloss;injectioncapacity;spatialanalysis

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