状态变量相关三维饱和黏土结构性本构模型

针对天然结构性饱和黏土具有大孔隙、强度高,具有一定胶结性的特点,将原有超固结土UH模型扩展为状态变量相关三维结构性模型。将p-q空间中屈服面左侧端点向原点左侧平移,使之能够考虑一定程度拉伸的胶结特性,并提出胶结性强度参数的演化规律方程。通过引入状态参量χ来修正屈服面方程,并给出状态参量的表达式,使得剪胀方程能够描述体变剪缩到剪胀的变相应力比强度特性。提出结构性应力比参量R^*的概念,并使之来修正统一硬化参量。基于t准则的变换应力方法,使该模型的应力表示一般化,使一般化后的模型能够描述真三轴的应力–应变关系。试验与预测对比结果表明,所提的三维结构性本构模型具有较强的适用性以及应用性。

A three-dimensional structural constitutive model of saturated clays related to state variables

In view of the characteristics of natural structural saturated clays such as large porosity,high strength and certain cementation,the UH model of over-consolidated soils was expanded into a three-dimensional structural model related to state variables. The left endpoint of the yield surface in the p-q space was shifted to the left of the origin,so that the cementing characteristics of a certain extent of stretching could be considered. The evolution equation of cementing strength parameters was proposed. By introducing a state parameter χ and deducing it’s expression,the yield surface equation was corrected so that the dilatancy equation can describe the strength characteristics of the variable phase stress ratio of the body changing from shear to dilatancy. The concept of structural stress ratio parameter R^* was proposed and used to modify the uniform hardening parameter. By using the transformation stress method based on t criterion,a generalized model of stress representation was proposed,which can describe the true triaxial stress-strain relationship. The comparison between test and prediction results shows that the proposed model has strong applicability.