A three-invariant continuum cap plasticity model with viscoplastic features is developed for modeling the large deformation of soil. Multiple failure mechanisms including combined shear and compaction yielding and loss of strength under tension can be captured by this model. The shear yield surface of the model is formulated to be nonlinear and pressure-dependent. The model also features a cap surface that governs inelastic compaction hardening. This cap is formulated as an explicit expression of porosity. The differences in triaxial compression and extension strength are also considered. A set of numerical examples are carried out, including triaxial compression and compression-shear tests, in order to examine the model under confined loading conditions, and observe the formation of shear bands.

中文翻译：

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土体大变形的硬化/软化粘塑性模型

建立了具有粘塑性特征的三不变连续体帽塑性模型，用于模拟土壤的大变形。该模型可以捕获多种失效机制，包括剪切和压实组合屈服以及张力下的强度损失。模型的剪切屈服面被公式化为非线性和压力相关的。该模型还具有一个控制非弹性压实硬化的盖面。该上限被公式化为孔隙度的明确表达。还考虑了三轴压缩和拉伸强度的差异。进行了一组数值示例，包括三轴压缩和压缩剪切试验，以在约束载荷条件下检查模型，并观察剪切带的形成。