Abstract: Stress-induced anisotropy is one of very important characters of soil and also key difference from metal material, which exist in many geotechnical projects. The traditional soil’s constitutive models, which are developed with the isotropic assumption, cannot describe such stress strain relationship. Based on a series of true-triaxial tests under complex stress states, basic anisotropic deformation mechanism and mechanical characteristics of soil are discovered, which will supply enough data for the establishment of anisotropy constitutive model. By considering the stress-induced anisotropy under complex stress states, new anisotropic elastic model and anisotropic plastic model may be developed., which can describe the stress-induced anisotropy.

Key words: stress induced anisotropy, soil’s constitutive model, true tri-axial test