上海典型黏土小應(yīng)變剪切模量現(xiàn)場和室內(nèi)試驗研究

上海典型黏土小應(yīng)變剪切模量現(xiàn)場和室內(nèi)試驗研究摘要本文基于實際現(xiàn)場和室內(nèi)試驗，探究了上海典型黏土的小應(yīng)變剪切模量特性。實驗方法包括常規(guī)土工試驗和動應(yīng)力三軸試驗等，通過分析試驗數(shù)據(jù)得出了黏土在小應(yīng)變下的剪切模量特征。研究發(fā)現(xiàn)，黏土的小應(yīng)變剪切模量隨著剪切速率的增加而增大，當(dāng)應(yīng)變幅度達到一定值時，黏土的剪切模量會呈現(xiàn)非線性增長特性。此外，本研究還對小應(yīng)變模量試驗數(shù)據(jù)進行了數(shù)理統(tǒng)計分析，得到了黏土剪切模量的基本統(tǒng)計參數(shù)，并建立了相應(yīng)的概率分布模型。這些研究成果對于加深黏土力學(xué)特性的理解，為相關(guān)工程設(shè)計提供了實用的技術(shù)參考。關(guān)鍵詞：黏土，小應(yīng)變，剪切模量，三軸試驗，統(tǒng)計分析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