多重耗散函数率无关塑性力学在粘土模型中的应用

由于经典的塑性力学无法根据Drucker塑性公设从理论上证明非相关联流动准则,因而从连续介质热力学基本原理出发研究土的弹塑性模型。根据率无关塑性力学理论,通过Gibbs自由能和多个独立耗散函数,建立土的多重屈服准则及其流动准则,证明了屈服准则重数和独立耗散函数个数相等,分析了耗散函数形式对屈服准则和塑性流动准则的影响。分析了一簇新的能够同时考虑相关联流动准则和非相关联流动准则的粘土的Gibbs自由能和耗散函数的表达式,殷宗泽双屈服面模型是其特例,但新模型具有更为明确的物理含义,能考虑非相关联流动准则的情况。根据粘土室内实验选取了模型参数,并与实测应力-应变曲线进行对比,说明新模型可以模拟粘土的多重屈服面本构关系。

Application of multiple dissipation potentials functions rate-independent plasticity model with applications to clay

Since non-associated flow rule cannot be derived theoretically from Drucker’s postulate in classical plasticity, the basic principles of thermo-mechanics in continua are applied to establish the elastic/plastic clay model. According to the theory of rate-independent plasticity, multiple yield criteria are constructed from the known multiple rate independent dissipation functions and it is proved that the number of yielding functions is equal to the number of independent dissipation functions. The influence of dissipation functions on yielding criterions and flow rule is studied. A new set of functions for clay are considered taking into account associated flow rule and non-associated flow rule, Gibbs free energy and multiple dissipation functions and experimental data. The empirically derived function from the present study will include the double yielding function plastic model provided by Yin Zong-ze. These new clay models can provide better physical meaning as well as including non-associated flow rule into the formulation. The parameters of the new model are determined by laboratory tests on clay. It is demonstrated that the new clay models can simulate the constitutive relation of clay with multiple yielding functions by comparing the theoretical stress-strain curve with the experiment stress-strain results.