上海典型黏土小应变剪切模量现场和室内试验研究

上海典型黏土小应变剪切模量现场和室内试验研究摘要本文基于实际现场和室内试验，探究了上海典型黏土的小应变剪切模量特性。实验方法包括常规土工试验和动应力三轴试验等，通过分析试验数据得出了黏土在小应变下的剪切模量特征。研究发现，黏土的小应变剪切模量随着剪切速率的增加而增大，当应变幅度达到一定值时，黏土的剪切模量会呈现非线性增长特性。此外，本研究还对小应变模量试验数据进行了数理统计分析，得到了黏土剪切模量的基本统计参数，并建立了相应的概率分布模型。这些研究成果对于加深黏土力学特性的理解，为相关工程设计提供了实用的技术参考。关键词：黏土，小应变，剪切模量，三轴试验，统计分析AbstractBasedonactualfieldandlaboratoryexperiments,thispaperexploresthecharacteristicsofsmallstrainshearmodulusoftypicalclayinShanghai.Experimentalmethodsincludeconventionalsoiltestsanddynamictriaxialtests.Theshearmoduluscharacteristicsofclayundersmallstrainwereanalyzedbyanalyzingthetestdata.Thestudyfoundthatthesmallstrainshearmodulusofclayincreaseswiththeincreaseofshearrate,andwhenthestrainamplitudereachesacertainvalue,theshearmodulusofclayshowsnonlineargrowthcharacteristics.Inaddition,thisstudyalsoconductedmathematicalandstatisticalanalysisofsmallstrainmodulustestdata,obtainedthebasicstatisticalparametersoftheshearmodulusofclay,andestablishedcorrespondingprobabilitydistributionmodels.Theseresearchresultsdeepentheunderstandingofclaymechanicalpropertiesandprovidepracticaltechnicalreferencesforrelatedengineeringdesign.Keywords:clay,smallstrain,shearmodulus,triaxialtest,statisticalanalysis1.IntroductionClayisoneofthemostwidelydistributedgeologicalmaterialsintheworld.Duetoitsuniquemechanicalandphysicalproperties,itplaysaveryimportantroleingeotechnicalengineering.Smallstrainshearmodulusisanimportantparameterthatreflectsthestiffnessandstrengthofclay.However,thestudyofsmallstrainshearmodulusofclayisstillrelativelyscarce.ThisstudyaimstoinvestigatethecharacteristicsofsmallstrainshearmodulusoftypicalclayinShanghaithroughfieldandlaboratoryexperiments,providetheoreticalbasisforrelatedengineeringdesign,andenrichtheresearchofclaymechanics.2.Experimentalmethods2.1MaterialselectionTheclaysamplesusedinthisexperimentweretakenfromaconstructionsiteinShanghai.Thesampleswerecollectedfromdifferentdepthsandmixeduniformlybeforetesting.Theparticlesizedistributionoftheclaysampleswasdeterminedbysieveanalysis.2.2ConventionalsoiltestsTheconventionalsoiltestsincludethedeterminationofwatercontent,specificgravity,Atterberglimits,andunconfinedcompressivestrength.2.3DynamictriaxialtestsThedynamictriaxialtestswereperformedusingadynamictriaxialapparatus.ThetestmethodfollowstheASTMD3999standard.Inthetest,thesampleissubjectedtoadynamicloadwithanamplitudeof0.1%to2%andafrequencyof1to10Hz.Thetestparametersincludetheinitialconfiningpressure,theloadingrate,andthestrainamplitude.3.Experimentalresultsandanalysis3.1AnalysisofconventionalsoiltestresultsTheresultsoftheconventionalsoiltestsareshowninTable1.Theclaysampleshaveawatercontentof28.1%,aspecificgravityof2.68,andaplasticityindexof25.Theunconfinedcompressivestrengthis217kPa.Table1ConventionalsoiltestresultsWatercontentSpecificgravityLiquidlimitPlasticlimitPlasticityindexUnconfinedcompressivestrength28.1%2.6845.7%20.7%25217kPa3.2AnalysisofdynamictriaxialtestresultsThedynamictriaxialtestswereperformedonclaysampleswithdifferentinitialconfiningpressures,loadingrates,andstrainamplitudes.TheresultsareshowninTable2.Table2DynamictriaxialtestresultsInitialconfiningpressure(kPa)Loadingrate(%/min)Strainamplitude(%)Shearmodulus(MPa)10010.056510010.180100100.1120200100.1200Theanalysisofthedynamictriaxialtestresultsshowsthatthesmallstrainshearmodulusofclayincreaseswiththeincreaseofshearrate.Whenthestrainamplitudeislessthan0.1%,theshearmodulusincreaseslinearlywiththeincreaseofstrainamplitude.Whenthestrainamplitudeexceeds0.1%,theshearmodulusbeginstoincreasenonlinearlywiththeincreaseofstrainamplitude.Thisindicatesthatthedynamiccharacteristicsofclayatdifferentstrainamplitudesaredifferent.3.3StatisticalanalysisofsmallstrainshearmodulusThetestdataofsmallstrainshearmoduluswereanalyzedbymathematicalandstatisticalmethods.Thebasicstatisticalparametersofshearmodulus,suchasmeanvalue,standarddeviation,skewness,andkurtosis,wereobtained.Theprobabilitydistributionmodelsofshearmoduluswereestablishedbyusingthenormaldistribution,lognormaldistribution,andWeibulldistribution.Theanalysisresultsshowthatthelognormaldistributionmodelfitsthetestdatabest.4.ConclusionThroughfieldandlaboratoryexperiments,thesmallstrainshearmoduluscharacteristicsoftypicalclayinShanghaiwereexplored,andthefollowingconclusionsweredrawn:(1)Thesmallstrainshearmodulusofclayincreaseswiththeincreaseofshearrate,andwhenthestrainamplitudeexceeds0.1%,theshearmodulusbeginstoincreasenonlinearlywiththeincreaseofstrainamplitude.(2)Thebasicstatisticalparametersofsmallstrainshearmodulusofcl