基于热力学的砂土统一模型

考虑剪胀对砂土内部状态的依赖，建立了统一的弹塑性本构模型以描述具有不同密度和应力水平的砂的变形特性。从热力学基本理论出发，根据能量耗散函数构造模型，建立初始状态参数与旋转硬化规律之间的关系，把状态变量间接引入剪胀函数。这种模型既考虑了剪胀与材料状态的联系，又由模型的热力学基础保证了屈服面和剪胀函数的协调。在给定模型参数和旋转硬化规律的条件下，模拟计算了排水和不排水三轴试验的结果，说明本文统一模型能够模拟松砂和密砂变形的一般规律。通过拟合Toyoura砂的部分三轴试验数据，确定模型参数；根据拟合获得的参数，计算了一组三轴试验曲线，计算结果与试验数据基本一致，验证了模型的有效性。

Unified mechanics model for sand based on thermomechanics

The different deformation curves of loose sand and dense sand can be simulated by a unified way by which the dependence of dilatancy on material state is considered. A proper energy dissipation function based on modern ideas of thermomechanics is used to develop the families of models describing the elasto-plastic behavior of soils. A modified model combining the theory of state-dependent dilatancy with thermodynamics laws is proposed. In the model, state dependence is introduced into dilatancy function indirectly by establishing the relationship between initial state parameter and rotation hardening rule. The model takes the dependence of dilatancy on initial state of material into account and guarantees the consistence of dilatancy function with yield locus because of the thermodynamics basis involved. The simulation capability of the proposed modified model is shown by computing general features of soil in triaxial drained or undrained tests with a unified model set of model parameters and rotation hardening rule. The parameters can be determined by fitting a part of triaxial test data of Toyoura sand. According to the obtained parameters a group of triaxial test curves are computed and compared with the experimental data to verify the validity of the model. The results show that the differences are acceptable.