Stress Direction Dependence of Soil (Ⅱ): Theory and Models

The stress directional dependence of soil, including the material direction (material anisotropy) and the stress direction (rotation of principal stress axis), is a hot and difficult issue of soil mechanics. Both the experiments and theoretical studies show that the anisotropy is the inner reason of the effect of principal stress axes rotation, and the complex stress state is the external reason of the anisotropy of soil. Therefore, these two factors should be considered in constitutive simulations. Related constitutive models can be roughly divided into three categories: (1) Macro constitutive models based on the theory of continuum mechanics and macro experimental phenomena; (2) Micro constitutive models based on micro-mechanism analysis; (3) Constitutive models based on the reasonable correlation between micro-mechanism and macro-phenomenon. By sorting out the modeling ideas of representative constitutive models, the treatment methods of the stress directional dependence of soil are analyzed, and the advantages and disadvantages of different modeling methods are summarized. It is expected to deepen the understanding of the stress directional dependence of soil and provide reference for geotechnical workers.