地震作用下可液化饱和自由场地动力响应

Dynamic response of liquefiable saturated free field under seismic action

针对既定埋深条件下的可液化自由场地在地震作用下动力响应问题,基于OpenSEES计算程序和有效应力动力分析方法,通过建立自由可液化饱和场地数值计算模型进行了耦合动力响应分析.计算结果表明:可液化场地β谱曲线卓越平台随埋深的增加而逐渐变窄,场地土层存在典型的高频滤波、低频放大效应;随着土层埋深和土层密实度增加,砂土层内的液化趋势明显减弱;饱和砂土和黏土层在地震作用下会分别发生剪缩效应和循环软化效应,进而使得土体产生不可恢复的残余变形及地表震陷.

Aiming at the dynamic response of liquefiable saturated free field with given burial depth under the seismic action,a coupled dynamic response analysis was performed by establishing numerical computing model for the liquefiable saturated free field,based on the OpenSEES computing programms and the dynamic analysis method for effective stress.The compting results show that the predominant platform for theβspectrum curve of liquefiable saturated free field gradually becomes narrow with the increase of buried depth.The soil layers of free field display the typical characteristics of high-frequency filtering and low-frequency amplification effects.With the increase of buried depth and densifying degree of soil layers,the liquefaction tendency of sand layer apparently weakens.The saturated sand and clay layers subjected to the seismic action will suffer the shear contraction and cyclic softening effects,which can lead to the irreversable residual deformation and ground surface subsidence.