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基于超固结黏土三维弹塑性本构模型,导出水-土耦合部分排水条件下饱和黏土应变局部化的萌生条件,求出在不同应力路径下,单相和水-土耦合条件下超固结土分叉的三维解析解和数值解。理论分析表明,应力罗德角θσ为-30°、15°和30°时,无论是单相条件,还是水土耦合两相介质条件,该模型均无分叉现象产生;应力罗德角为0°时,单相条件下该模型有分叉现象产生,水土耦合不排水条件下该模型无分叉现象出现,水-土耦合部分排水条件下分叉与否则与参数选取有关;应力罗德角为-15°时,无论是单相条件,还是水-土耦合条件,该模型均有分叉现象产生。利用嵌入了上述本构模型的有限元软件ABAQUS,对单相和水-土耦合条件下的多单元立方体应变局部化分叉现象进行数值分析。分析表明,在应力罗德角为±30°时,单相条件和水土耦合条件下都无分叉现象产生;应力罗德角为15°时,单相条件下有分叉现象产生,水-土耦合不排水条件下无分叉现象出现,水-土耦合部分排水条件下何时分叉则与渗透系数大小有关;应力罗德角为-15°和0°时,单相条件和水土耦合条件下该模型均有分叉现象产生。同一应力路径下数值解相对于理论解更易出现分叉。
Based on the three-dimensional elasto-plastic constitutive model of overconsolidated clay, the initiation conditions of strain localization of saturated clay under the drainage condition of water-soil coupling are deduced, and the overconsolidation under different stress paths with single-phase and water- Three - dimensional analytic solution and numerical solution of soil bifurcation. Theoretical analysis shows that there is no bifurcation in the model when the θr of stress Rhode angle is -30 °, 15 ° and 30 °, both in single-phase condition and in medium-water-soil coupled two-phase condition. The stress Rhode angle is 0 °, the bifurcation of the model occurs under single-phase conditions. No bifurcation occurs in this model under undrained coupling of water and soil, and the bifurcation under the drainage condition of water-soil coupling is related to the parameter selection. The stress Rhode angle At -15 °, the model has bifurcations both in single-phase conditions and in water-soil coupling conditions. The finite element software ABAQUS with the above constitutive model was used to analyze the localized bifurcation phenomenon of multi-unit cubic strain under single-phase and water-soil coupling conditions. The analysis shows that there is no bifurcation when the stress Rhode angle is ± 30 ° under single-phase conditions and soil-water coupling conditions. When the stress Rhode angle is 15 °, bifurcation occurs under single-phase conditions. The water- Under the conditions of undrained soil coupling, no bifurcation occurs, and when the water-soil coupling part is drained, the time-dependent branching is related to the permeability coefficient. When the stress Rhode angle is -15 ° and 0 °, The model has bifurcation under the conditions. Under the same stress path, the numerical solution is more prone to bifurcation than the theoretical solution.