地震激励下桩－土非线性耦合作用对桩基动力响应特性的影响

摘要

为探讨桩－土非线性耦合作用对桩基动力响应特性的影响，以桩－土－结构耦合系统为研究对象，建立三维非线性有限元模型。采用 Drucker-Prager 非线性土体本构模型，利用罚函数法实现桩－土－结构界面间的非线性耦合作用，引入无反射边界条件，并考虑重力因素，得到了水平和竖直方向组合地震激励下桩－土非线性相互作用对桩基地震响应的影响。结果表明，考虑桩－土接触非线性，桩基的加速度响应峰值减小，桩土之间出现明显的分离现象，桩基剪力和弯矩峰值有所增加。通过对桩基轴力的校核，桩基不承受拉力，不会发生拔桩现象。%The dynamic response features of pile foundations with soil-pile nonlinear coupling actions were investigated by conducting nonlinear 3D finite element numerical simulations.The soil-pile nonlinear coupling actions, such as,non-reflecting boundary condition and soil-pile dynamic interaction were modeled with the penalty function method.The simulation results showed that considering the nonlinearity of soil-pile contact,the peak acceleration of pile foundation decreases;the obvious phenomenon of separation between soil and piles appears;the shear force and bending moment increase due to soil-pile nonlinear interaction;there is no axial tensile force in piles.