Explanation of cyclic mobility of soils: Approach by stress-induced anisotropy

In this paper, a new constitutive model is proposed to describe the mechanical behaviors of soils under different loading conditions. New evolution equations for the development of stress-induced anisotropy and the change of over-consolidation of soils are proposed. By combining systematically the above two evolution equations with the evolution equation for the structure of soil proposed by Asaoka et al. (2002), the newly proposed model is able to describe not only the mechanical behavior of soils under monotonic loading, but also the behavior of soils under cyclic loading with different drained condition. Special attention is paid to the behavior of sand subjected to cyclic loading under undrained condition. That is, for given sand with different densities, very loose sand may liquefy without cyclic mobility, medium dense sand will liquefy with cyclic mobility while dense sand will not liquefy, which is just controlled by the density, the structure and the anisotropy of the sand. A suitable model should uniquely describe this behavior without changing its parameters. Present research will show the possibility of the proposed model.