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。 Based on the three-dimensional elastic-plastic constitutive model of the over-consolidated clay of Fleshivian surface proposed by Yao Yangping et al., The initiation conditions for the strain localization of saturated clay under undrained coupling of water and soil were derived. Single-phase Three - dimensional analytical solutions and numerical solutions of bifurcation under undrained coupling between medium and soil and water. Theoretical analysis shows that for single-phase media, the bifurcation occurs in the constitutive model when the stress Rhodes angle is between -23.5 ° and 4 °, and the bifurcation occurs in the hardening phase of soil stress-strain curve. No bifurcation occurs when the stress Lode angle is between -30 ° -23.5 ° and 4 ° -30 °. Under the conditions of soil-water coupling and undrained drainage, bifurcation occurs when the stress Rhode angle is between -23 ° -1 °, and the bifurcation occurs in the softening stage of soil stress-strain; The angle of bout occurs when the angle is between -30 ° and -23 ° and between -1 ° and 30 °. Using the finite element software ABAQUS embedded in the above constitutive model, the numerical analysis of strain localized bifurcation of multi-unit cube under the condition of single-phase and soil-water coupling undrained condition was carried out. Comparison shows that the analytical solution and numerical simulation results are basically the same.