平面应变条件下水土耦合超固结黏土分叉分析

Bifurcation analysis of water-soil coupled overconsolidated clay under plane strain condition

基于Hvorslev面超固结黏土三维弹塑性本构模型,导出在不排水和排水固结条件下饱和黏土的应变局部化分叉条件,分析不同渗透系数、排水路径长度和应变速率对分叉的影响.理论分析表明,在平面应变条件下,土体应变局部化分叉随着孔隙水的流动程度发生显著变化.利用嵌入上述本构模型的有限元软件ABAQUS,在平面应变应力路径下对加载面排水的多单元立方体应变局部化分叉现象进行数值分析.结果表明:当排水路径长度和应变速率一定时,渗透系数越大,应变局部化分叉出现得越早;当渗透系数一定时,排水路径长度和应变速率越大,应变局部化分叉出现得越晚;当时间因数一定时,应变局部化分叉出现时对应的剪应变一定.

Based on the Hvorslev＇s envelope-based three-dimensional elastoplastic constitutive model for overconsolidated clay, an acoustic tensor of bifurcation for strain localization under undrained and drained conditions was obtained in the explicit form. The influences of permeability, drainage path length and strain rate on the bifurcation were analyzed. Theoretical results show that the strain localization bifurcation is related to the water seepage for water-soil two-phase material. The numerical simulation of plane strain tests on a cubic specimen for the bifurcation under drained condition was conducted by using a nonlinear finite element analysis software ABAQUS with the model being implemented. Numerical results show that the greater the permeability, the sooner the bifurcation occurs when the drainage path length and the strain rate are fixed; when the permeability is fixed, the greater the drainage path length and the strain rate, the later the bifurcation occurs; the strain corresponding to the bifurcation is constant when the time factor is given.