简介：AsimplecyclicelastoplasticconstitutivemodelforsandisproposedbasedontheUHmodelforoverconsolidatedclay.Theproposedmodelhasthefollowingfeatures.First,inordertodescribethestress-inducedanisotropyinsand,arotationalhardeningruleisintroducedfortheevolutionoftheyieldsurfaceaxiswithdevelopmentofplasticdeviatoricstrainintheprincipalstressspace.Second,therelationshipbetweentherotationalaxisandstress-inducedanisotropyismodeledbyintroducingtheslopeofrotationalaxisintotheyieldfunction.Theflatnessoftheyieldsurfacecanbedeterminedbytheslopeofrotationalaxis.Finally,arevisedunifiedhardeningparameterisproposedtoincorporatethestress-inducedanisotropy.Themodelcapabilityindescribingthecyclicresponseofsandisverifiedbycomparingthesimulationswithavailabletestresults.

简介：Theperformanceofawell-designedlayerofsand,andcompositeslikelayerofsandmixedwithshreddedrubbertire(RSM)aslowcostbaseisolators,isstudiedinshaketabletestsinthelaboratory.Thebuildingfoundationismodeledbya200mmby200mmand40mmthickrigidplexi-glassblock.Theblockisplacedinthemiddleofa1mby1mtankfilledwithsand.Theselectedbaseisolatorisplacedbetweentheblockandthesandfoundation.Accelerometersareplacedontopofthefootingandfoundationsandlayer.ThedisplacementofthefootingisalsomeasuredbyLVDT.Thewholesetupismountedonashaketableandsubjectedtosinusoidalmotionswithvaryingamplitudeandfrequency.Sandisfoundtobeeffectiveonlyatveryhighamplitude(>0.65g)ofmotions.Theperformanceofacompositeconsistingofsandand50%shreddedrubbertireplacedunderthefootingisfoundtobemostpromisingasalow-costeffectivebaseisolator.

简介：ShanghaiislocatedineasternChinaandisbuiltonoverburdensoillayers.ItcanbeseenfromtheMexicoMs=8.1earthquakeonSeptember19,1985andtheHanshinMs=7.4earthquakeonJanuary17,1995thatheavycasualtiesandpropertylosseshaveadirectrelationshipwithoverburdensoillayers.Groundmotionscausedbyearthquakesaresignifieantlyamplifiedwhenpassingthroughthesoillayers.Undertheinfluenceoftheseamplifiedmotions,buildingstructures,whosenaturefrequencyiswithinthefrequencybandofsoilamplificationresponse,willexperiencemoreseveredamagethanthosebuiltonbedrock.Therefore,engineeringseismologistshavepaidconsiderableattentiontheamplificationresponsesintheShanghaioverburdensoillayers.TheamplificationresponsesofsoilandsandlayersinthispaperaregivenbytheML=4.1earthquakeinNantong,JiangsuProvinceonDecember25,2001at31.8°N,120.9°E.Itcanbeseenthattheresponsesofsoilandsandlayersareverydifferent.Thatisimportant.

简介：在一些液化的沙存款的加速记录展出特殊尖刻的波形，由强壮的扩大和高周波的部件描绘了。一个全面组成的模型被用来分析如此的尖刻的加速回答的机制。一个理想化的single-degree-of-freedom(SDF)系统被构造，在哪个春天的力量排水量关系在砍的undrained期间跟随浸透的沙的压力紧张行为。SDF系统证明尖铁是直接与沙的变硬紧张的行为有关在液化以后的周期的砍期间。而且，在那里存在阀值砍拉紧长度，它根据有限振幅像液体砍产生在的紧张即时在液化以后的阶段期间州的零个有效压力。当时，尖刻的加速能仅仅发生周期砍紧张超过阀值砍紧张长度。因为，在加速尖铁之间的时间间隔与摇晃的继续一起逐渐地增加，这也被揭示因为阀值砍紧张长度增加逐渐地然后更，时间被需要产生更大砍引起紧张变硬的紧张。在Kushiro港口地点和港口岛地点的记录通过充分联合的方法在过去的地震期间被模仿验证介绍机制。