A non-equilibrium statistical thermodynamics-based framework for describing elasto-viscoplastic deformations in amorphous materials termed shear-transformation-zone (STZ) theory has been implemented in the material point method (MPM) and applied to the modeling of large-deformation geomechanical problems. Plane strain biaxial shear tests with different loading rates were first performed using the model to emphasize its rate-dependency and to compare its performance with that of a μ(I) rheological model. The model was then utilized to simulate three classical large-deformation geomechanical problems, namely, the granular column collapse, the footing settling on a soft ground, and the soil-pipe interaction. It has been shown from this study that the STZ theory is promising in modeling rate-dependent viscoplastic behaviors of geomaterials, as well as solid–fluid phase transition and strain localization.

在材料点方法（MPM）中已实现了一种基于非平衡统计热力学的框架，用于描述非晶材料中的弹粘塑性变形，称为剪切变形区（STZ）理论，并将其应用于大变形岩土力学问题的建模。首先使用该模型进行了具有不同加载速率的平面应变双轴剪切测试，以强调其速率相关性并将其性能与μ（I）流变模型。然后，该模型用于模拟三个经典的大变形岩土力学问题，即颗粒柱塌陷，在软土地基上的立足以及土管相互作用。这项研究表明，STZ理论在模拟与速率相关的土工材料的粘塑性行为以及固液相变和应变局部化方面很有前途。