ASTM D4945-2008 基桩高应变动力检测的标准试验方法

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【英文标准名称】:StandardTestMethodforHigh-StrainDynamicTestingofPiles
【原文标准名称】:基桩高应变动力检测的标准试验方法
【标准号】:ASTMD4945-2008
【标准状态】:现行
【国别】:美国
【发布日期】:2008
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:D18.11
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:augeredpiles;deepfoundations;drilledshafts;drivenpiles;drivingstresses;dynamictesting;pilebearingcapacity;piledrivinghammerperformance;pileintegrity;Accelerometers;Bearingcapacity;Displacement;Force;Impacttesting--soil/rock/rel
【摘要】:Basedonthemeasurementsfromstrainorforce,andacceleration,velocity,ordisplacementtransducers,thistestmethodobtainstheforceandvelocityinducedinapileduringanaxialimpactevent(seeFigs.1and2).TheEngineermayanalyzetheacquireddatausingengineeringprinciplesandjudgmenttoevaluatetheintegrityofthepile,theperformanceoftheimpactsystem,andthemaximumcompressiveandtensilestressesoccurringinthepile.Ifsufficientaxialmovementoccursduringtheimpactevent,andafterassessingtheresultingdynamicsoilresponsealongthesideandbottomofthepile,theEngineermayanalyzetheresultsofahigh-straindynamictesttoestimatetheultimateaxialstaticcompressioncapacity(seeNote1).Factorsthatmayaffecttheaxialstaticcapacityestimatedfromdynamictestsinclude,butarenotlimitedtothe:(1)pileinstallationequipmentandprocedures,(2)elapsedtimesinceinitialinstallation,(3)pilematerialpropertiesanddimensions,(4)type,density,strength,stratification,andsaturationofthesoil,orrock,orbothadjacenttoandbeneaththepile,(5)qualityortypeofdynamictestdata,(6)foundationsettlement,(7)analysismethod,and(8)engineeringjudgmentandexperience.IftheEngineerdoesnothaveadequatepreviousexperiencewiththesefactors,andwiththeanalysisofdynamictestdata,thenastaticloadtestcarriedoutaccordingtoTestMethodD1143shouldbeusedtoverifyestimatesofstaticcapacityanditsdistributionalongthepilelength.TestMethodD1143providesadirectandmorereliablemeasurementofstaticcapacity.Note18212;Theanalysisofadynamictestwillunderpredicttheultimateaxialstaticcompressioncapacityifthepilemovementduringtheimpacteventistoosmall.TheEngineershoulddeterminehowthesizeandshapeofthepile,andthepropertiesofthesoilorrockbeneathandadjacenttothepile,affecttheamountofmovementrequiredtofullymobilizethestaticcapacity.Apermanentnetpenetrationofaslittleas2mmperimpactmayindicatethatsufficientmovementhasoccurredduringtheimpacteventtofullymobilizethecapacity.However,highdisplacementdrivenpilesmayrequiregreatermovementtoavoidunderpredictingthestaticcapacity,andcast-in-placepilesoftenrequirealargercumulativepermanentnetpenetrationforaseriesoftestblowstofullymobilizethecapacity.Staticcapacitymayalsodecreaseorincreaseovertimeafterthepileinstallation,andbothstaticanddynamictestsrepresentthecapacityatthetimeoftherespectivetest.Correlationsbetweenmeasuredultimateaxialstaticcompressioncapacityanddynamictestestimatesgenerallyimprovewhenusingdynamicrestriketeststhataccountforsoilstrengthchangeswithtime(see6.8).Note28212;Althoughinterpretationofthedynamictestanalysismayprovideanestimateofthepile''stension(uplift)capacity,usersofthisstandardarecautionedtointerpretconservativelythesideresistanceestimatedfromanalysisofasingledynamicmeasurementlocation,andtoavoidtensioncapacityestimatesaltogetherforpileswithlessthan10membeddedlength.(Additionaltransducersembeddednearthepiletoemayalsohelpimprovetensioncapacityestimates.)IftheEngineerdoesnothaveadequatepreviousexperienceforthespecificsiteandpiletypewiththeanalysisofdynamictestdatafortensioncapacity,thenastaticloadtestcarriedoutaccordingtoTestMethodD3689shouldbeusedtoverifytensioncapac........
【中国标准分类号】:P20
【国际标准分类号】:93_020
【页数】:10P.;A4
【正文语种】:英语