Isotropic hardening model for soils considering stress-induced anisotropy

A simple method for describing stress-induced anisotropy of soils, which obeys isotropic hardening rule in modified stress space, is proposed. In present study, a modified stress t(ij), by which influence of intermediate principal stress on deformation and strength characteristics of soils is suitably taken into account, is extended to a new stress tensor t(ij)(*) to be able to consider inclusively the fabric change of soils due to the variation of the intermediate principal stress and the stress histories, namely, stress-induced anisotropy. The evolution rule of t(ij)(*) is provided referring to the past experimental and numerical evidences. In this paper, the modified stress t(ij)(*) is applied to an isotropic hardening elastoplastic model named subloading t(ij) model as an example. The proposed model is verified by results of true triaxial tests.