卸荷土体本构模型选用及其参数的确定--以港珠澳大桥拱北隧道明挖段基坑为例.pdfVIP

卸荷土体本构模型选用及其参数的确定—— 以港珠澳大桥拱北隧道明挖段基坑为例 柳志平1 刘泉声1 程勇2贾瑞华2 蒋景东1 1.武汉大学士木建筑工程学院，湖北武汉4300722.中交第二公路勘察设计研究院有限公司，湖北武汉430056 摘要：对卸荷土体工程性质的认识是解决基坑开挖工程中问题的关键，港珠澳大桥连接线珠海拱北隧道处于海相软 黏土地层，基坑开挖深度大，断面宽，研究该基坑土体在卸荷应力路径下的土体本构模型及其参数，对工程设计有着 重要的意义。取现场土样，选定海相沉积的淤泥质土和可塑状粉质黏土作为研究对象，测定其K0值，采用应力控制式 三轴仪，在围压100，200，400，600kPa状态下进行K0排水固结，对固结完成的土样进行不同应力路径的卸荷试验， 根据应力-应变关系曲线的非线性特征，采用邓肯张E-μ模型作为该基坑土体的本构模型，依照试验结果，分别确定 邓肯张E-μ模型的8个基本参数，为基坑有限元分析提供重要依据。 关键词：基坑；卸荷试验；邓肯张模型；模型参数 中图分类号：TU473 文献标识码：A Selectionandparametricdeterminationofconstitutivemodelforunloading soil—Casestudyoffoundationpitatopenexcavationsection ofGongbeitunnelofHongkong-Zhuhai-MacauBridge LIUZhi-ping1LIUQuan-sheng1,CHENGYong2,JIARui-hua2,JIANGJing-dong1 1.SchoolofCivilEngineeringArchitecture,WuhanUniversity,Wuhan430072,China;2.CCCCSecondHighwayConsultantsCo.,Ltd.,Wuhan430056,China Abstract:Theunderstandingofengineeringpropertiesofunloadingsoilisthekeytosolvingtheproblemsinexcavationof foundationpits.GongbeitunnelinZhuhaiofHongkong-Zhuhai-MacauBridgeislocatedinmarinefaciessoftclay.The excavationdepthandwidthofitsfoundationpitarebothverylarge.Theresearchesonofconstitutivemodelandmodel parametersofthefoundationpitsoilunderunloadingstresspathareofgreatsignificancetotheengineeringdesign.Themarine facessediment-muckysoilandplasticsiltyclayarearestudiedsoastodeterminetheirK0coefficients.K0drainedconsolidation expririmentsareperformedundertheconfiningpressuresof100,200,400and600kPabyusingthestresscontrolledtriaxial apparatus.Unloadingtestswithvariousstresspathsareconductedafterthesoilsamplesarecompletelyconsolidated.According tothenon-linearfeatureofstress-strainrelationshipcurve,theDuncan-ZhangE-μmodelisadoptedastheconstitutivemodel forsoil.Accordingtotheexperimentalresults,8basicparametersaredetermined,andthisstudyprovidesimportantbasisfor theFEManalysisofthefoundationpi