土坝的地震响应及液化无网格法分析

Meshless analysis on seismic response and liquefaction of embankments

以Biot固结理论的u-p列式作为饱和砂土的控制方程,应用有效循环弹塑性模型建立土的本构关系,并运用更新的Lagrange大变形算法分析液化后土体的大变形行为。利用移动最小二乘法近似推求形函数,再采用伽辽金法对控制方程离散,获得无网格伽辽金法的基本计算方程以进行无网格法分析。通过算例证明了该方法能避免液化大变形有限元分析时由于网格畸变而引起的计算中断问题。将无网格法应用于某坝的地震响应分析。计算结果表明:坝顶的加速度在液化前较输入加速度有一定的放大,在液化后加速度显著减小,且振动周期变长;坝体下部和坝趾处土体相对于其他区域不容易发生液化。

The governing equations of liquefaction of embankment were established based on u-p formulation of Blot s two-phase mixture theory,and a cyclic elastic constitutive model and improved Lagrange large-deformation method were jointly adopted to take both physical and geometrical nonlinearities into account.The shape functions were established by moving least square method.On this basis,the Galerkin method was used to discretize the governing equations and establish the basis function equations of the element-f...