非线性准则下多孔岩土体弹塑性变形推导与数值模拟

Elasto-plastic deformation derivation and numerical simulation of pore geo-material by non-linear law

基于临界状态塑性模型,针对多孔岩土材料,从非线性的弹性本构方程出发,对其率形式进行积分求解,得到弹性行为下切线应力-应变模量的表达式;在此基础上,引入一致性系数,对非线性准则下弹塑性变形本构方程的增量形式进行应力积分求解;编制大型有限元计算程序以及积分求解核心算法程序,再现饱和砂土边坡液化的形成过程。研究结果表明:在边坡局部剪切带即将形成的区域,孔隙水压力明显增大,而且沿着剪切带的外法线方向向外流动;在远离剪切带区域,水压力分布较均匀,且流动方向趋于水平;根据液化发生准则,得到了边坡发生液化的滑动面。

Based on the critical state plasticity model,an integration algorithm of the rate form for the non-linear elastic constitutive equations was performed to gain the tangent stress-strain of the elastic behavior;then the coincidence coefficient was introduced to calculate the incremental form of the elasto-plastic deformation constitutive equations under non-linear law.At last,a finite element program and an integration algorithm were coded by FORTRAN to simulate the onset of the liquefaction of a sand slope.The results show that the pore pressure affects the onset and development of the deformation band greatly,and the pore pressure increases around the localization-prone regions obviously with the direction toward the outer side of the normal of the shear band,while the pore stress flows nearly horizontally and is distributed equality far away from the shear band region.The sliding surface of the slope can be derived when the liquefaction happened,according to the law of the onset of liquefaction.