液化地基中群桩基础地震响应分析

可液化地基中桩基础地震响应分析一直是岩土工程抗震研究的热点和难点。针对这一问题,采用砂土液化大变形统一本构模型来描述可液化地基土体的应力应变关系,建立了一个3×5的群桩三维计算模型,采用三维弹塑性有限元动力时程分析,将地基、群桩基础和上部结构作为一个系统研究群桩基础的地震动响应规律,重点关注桩与土的运动相互作用以及水平方向的弯矩在地震荷载作用下的分配情况。结果表明可液化地基中桩基础的弯矩受桩与土运动相互作用影响显著;不同桩的弯矩最大值不同,角桩最大,边桩次之,中心桩最小;弯矩最大值出现的位置不相同,角桩和边桩弯矩最大值出现在上部非液化层与液化层界面处,中心桩弯矩最大值出现在桩头处。

Seismic response analysis of pile groups in liquefiable foundations

The seismic analysis of pile foundations in liquefiable ground is an important subject in geotechnical earthquake engineering. A computational model of a 3×5 pile group is established in OpenSees FEM program, and considering soil foundations, the pile group and the upper structure as a system, a unified plastic constitutive model for large post-liquefaction deformation of sand is employed. Special attention is given to the kinematic interaction between piles and soil and distribution of the moment in pile groups. The results show that the soil-pile kinematic interaction has a significant influence on the moment of piles in liquefiable ground. The moment distribution in pile groups indicates that the maximum moment of the corner piles is the largest, and that of the central piles is the smallest. The positions of the maximum moment of different piles are different. The maximum moments in the corner piles and the edge piles are at the interface between the upper layer and the liquefied layer, but the maximum moment in the central piles is at the pile top.