饱和砂土中直群桩及土体地震动力响应特征研究  

Seismic response characteristics of straight group piles and soil in saturated sand

作　　者：闫志晓 李雨润 张健[1] YAN Zhixiao;LI Yurun;ZHANG Jian(College of Civil Engineering and Transportation,Hebei University of Technology,Tianjin 300401,China;Civil Engineering Technology Research Center of Hebei Province,Hebei University of Technology,Tianjin 300401,China)

机构地区：[1]河北工业大学土木与交通学院,天津300401 [2]河北工业大学河北省土木工程技术研究中心,天津300401

出　　处：《振动与冲击》2020年第18期44-53,共10页Journal of Vibration and Shock

基　　金：国家自然科学基金(51778207,51008110);河北省自然科学基金(E2018202107);河北省研究生创新资助项目(CXZZBS2019041)。

摘　　要：为了更好地研究地震作用下饱和砂土中群桩及土体动力响应特征,设计了饱和砂土液化场地2×2直群桩动力响应离心机振动台试验,获得承台、土体加速度以及孔压动力时程曲线。为了更深入地分析群桩及土体地震动力响应特征并满足对比研究的需要,在试验基础上,基于ABAQUS有限元软件平台,通过引入砂土液化大变形本构模型,采用有限元网格自适应调整技术克服大变形畸变问题,建立液化场地群桩基础静动耦合非线性相互作用的二维有限元模型进行数值模拟分析,并与试验结果进行对比验证。结果表明:在峰值加速度0.3 g El-Centro地震波工况下离心机振动台试验饱和砂土地基液化速度非常快,直群桩基础承台加速度相比较输入波明显缩小,0.3 g大震作用下地基浅层加速度显著衰减,地基液化区域由浅入深逐渐发育;饱和砂土地基超静孔隙水压力发展影响土体和桩基承台加速度响应,土体液化直接导致加速度数值减小;数值模拟加速度结果与试验的加速度动力响应特性略有区别,数值模拟加速度地基浅层出现先放大后缩小的规律,深层土与输入波形基本一致;数值模拟超静孔隙水压力与超静孔压比与试验基本一致,而模拟得到的承台位移结果相较于试验偏于保守。In order to study the dynamic response characteristics of group piles and soil in saturated sand under earthquake action,a dynamic response shaking table test of 2×2 straight group piles in saturated sand liquefaction site was designed and the time history curves of the cap motion,soil acceleration and pore pressure were obtained.In the meantime,a numerical model was built on the ABAQUS finite element software platform to analyze the seismic response characteristics of the group piles and the soil.In the two-dimensional finite element model the static and dynamic coupled nonlinear interaction of the group pile foundation in liquefaction site was considered.A large deformation constitutive model for sand liquefaction and the finite element mesh adaptive adjustment technique were introduced to deal with the distortion induced by the large deformation.The numerical results were compared with the experimental results.The results show that in the shaking table test under 0.3 g peak acceleration El-centro seismic wave condition,saturated sand soil has a very fast liquefaction rate.Under the action of 0.3 g large earthquake,the acceleration on the shallow layer of the foundation soil is significantly attenuated.The development of pore water pressure in the saturated sand foundation affects the acceleration responses of the soil and pile foundation cap.Soil liquefaction directly leads to a reduction in the acceleration magnitude.The numerical simulation shows that the acceleration on the shallow layer of the foundation increases first and then scales down,and that in the deep soil is basically consistent with the input waveform.The numerical simulation results of the excess pore water pressure and the excess pore pressure ratio are basically the same as those of the test,and the simulated results of the pile displacement are more conservative than the test ones.

关 键 词：离心机振动台试验 饱和砂土 直群桩 数值模拟 动力响应特征 

分 类 号：TU43[建筑科学—岩土工程]