中文摘要：

基于姚仰平等提出的伏斯列夫面超固结黏土三维弹塑性本构模型,导出了水土耦合不排水条件下饱和黏土的应变局部化的萌生条件,求出了在不同应力路径下单相介质和水土耦合不排水条件下分叉三维解析解和数值解。理论分析表明,对于单相介质,该本构模型在应力洛德角为-23.5°～4°之间时,有分叉现象产生,并且分叉产生于土体应力应变曲线的硬化阶段;而当应力洛德角在-30°～-23.5°和4°～30°之间时无分叉现象出现。在水土耦合不排水条件下,使用该模型在应力洛德角为-23°～-1°之间时,有分叉现象产生,分叉产生于土体应力应变的软化阶段;而当应力洛德角在-30°～-23°和-1°～30°之间时无分叉现象出现。利用嵌入上述本构模型的有限元软件ABAQUS,对单相和水土耦合不排水条件下的多单元立方体应变局部化分叉现象进行了数值分析。比较表明解析解与数值模拟的结果基本一致。

英文摘要：

Based on the Hvorslev＇s envelope-based three-dimensional elastoplastic constitutive model proposed by Yao et al.for over-consolidated clays,an acoustic tensor and a discriminator of bifurcation for strain localization under undrained conditions are given in an explicit form.The analytical and numerical solutions to the model under different stress paths are resolved.The theoretical analysis shows that onset of bifurcation occurs in the hardening regime at the Lode angle in the range of-23.5o ~ 4o when the material is single-phase.There is no bifurcation occurring at the Lode angle in the ranges of-30o~23.5o and 4o~ 30o.On the other hand,onset of bifurcation occurs in the softening regime at the Lode angle in the range of-23o ~-1o when the material is two-phase consisting of soil skeleton and water,and there is no bifurcation occurring at the Lode angle in the ranges of-30o~23o and-1o~ 30o.The numerical simulations of cubic specimens of the single-phase and water-soil coupling saturated porous media under undrained condition for the bifurcation are carried out by use of a nonlinear finite element analysis software ABAQUS with the above model being implemented.A comparison indicates that the numerical results agree with the theoretical solutions.