基于细观分析的黏土本构模型

A constitutive model for clay based on micro mechanics method

根据黏性土在固结排水条件下的加、卸载变形特征,分析了孔隙水,固体骨架在不同变形阶段的力学响应行为,按照细观力学分析中的自洽方法,建立了在固结排水条件下的黏土损伤本构模型。模型中考虑了孔隙水和固体骨架在加、卸载阶段的不同特性,认为在损伤阶段整体剪切模量的降低是由固体骨架颗粒接触面滑移而引起,与骨架中滑动相的体积百分比和滑动相的剪切模量有关,并给出了求解整体变形模量的解析方法,最后将模型预测与不同初始固结压力,不同应力路径的排水试验结果作了比较,证明该模型是合理的。

Based on analyzing the experimental results of saturated clay under the consolidated drained condition, a micromechanical damage constitutive model of consolidated drained saturated clay is presented by micromechanical analysis about every phase in clay. This model views that clay is composed of pore water and joint solid skeleton at the onset of loading until the joint solid skeleton is subjected to damage. The damage of the joint solid skeleton is defined as the slide of clay grain interface. In the damage deformation stage, the clay specimen is composed of three phase, such as pore water, joint solid skeleton and sliding solid skeleton. The volume fraction and the shear modulus of the sliding phase vary with loading process. This paper gives a method to calculate the volume fraction of the sliding phase in terms of Mohr-Coulomb law and the modulus decrease of the sliding phase in terms of conventional triaxial test. In addition, this work explores the hypothesis under which the nonlinear response of the clay is entirely due to the increase of the sliding phase volume fraction and the decrease ~of the sliding phase shear modulus. An averaging schemes based on self-consistent method are found to get a realistic transition from the relevant information available at the microscale to the overall nonlinear response at the macroscale. This paper also gives an approach to obtain micro-parameter and loading-unloading principle. Finally, tests on the versatility of the proposed model, including varying consolidated pressures and stress paths, indicate that the proposed model is capable of predicting deformation behavior for various conditions.