液化侧向流动场地桩基动力反应振动台试验三维有限元数值模拟方法

Three-dimensional finite element analysis of shake-table test for dynamic pile behavior in liquefaction-induced lateral spreading ground

将饱和砂土模拟为两相介质,采用水-土动力耦合理论建立的u-p有限元公式,表示水的孔压、土颗粒的变形,以及二者之间动力耦合关系。砂土采用新近基于多屈服面塑性理论发展的土的动力弹塑性本构模型模拟,砂土划分为20-8节点的水土耦合实体单元。针对土箱整体微倾2°的大型振动台试验,建立液化侧向流动场地桩-土动力相互作用分析的三维非线性有效应力有限元数值模型。对比得到,有限元数值分析结果能够与振动台试验结果吻合较好,数值结果可以较好地显示试验中桩和土的重要动力特性。通过校正的数值模型,可进一步考察液化侧向流动场地桩-土动力相互作用的影响因素。

A solid-fluid fully coupled formulation u-p is employed to model soil displacement and pore pressure in the sand as the two phase medium and characterize the interaction between fluid and soil skeleton. A recently developed soil constitutive model based on a multi-surface plasticity framework is chosen to simulate the sand. The solid-fluid fully coupled( u-p) 20-8 node brick elements are used to discrete the sand domains. A three-dimensional nonlinear dynamic finite element analysis was conducted to simulate a shake-table experiment with 2 degree inclination on dynamic pile behaviour subjected to liquefaction-induced lateral spreading. The finite element analysis has produced a model response reasonably matched the shake-table experiment after careful calibration.