关键词: 黏土, 细观力学, 自洽方法, 滑移, 本构模型

Abstract: 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.

Key words: clay, micromechanics, self-consistent method, sliding phase, constitutive model