Abstract: To reflect the different mechanical characteristics of sand under high and low pressures, the mechanical test results of sand, i.e., the strength, isotropic compression and critical state characteristic parameters, under a large range of confining pressure are analyzed to build a unified model. Correlation factor of stress path is used to adjust the plastic deformation related to stress path, and the hardening parameter can be used to describe the dilatancy behavior of relatively dense sand under low pressure. Based on the critical state behavior of sand, potential state surface is proposed to reflect the sand inherent state. With the dynamic relationship between the yield surface and potential state surface, the current compactness parameter and potential strength of sand are defined. The hardening parameter can reflect shear softening and shear contraction hardening properties of relatively dense sand under low and high pressures. Evolution law of yield surface and potential state surface is analyzed, and model prediction under different pressures is carried out. Results comparison validates the proposed model with the capability to reflect shear dilatancy softening and shear contraction hardening properties of sand under different pressures.

Key words: sand, high pressure, mechanical properties, hardening parameter, constitutive model