A Double Modified Plastic Work-Hardening Constitutive Model for Sand under Plane-Strain Conditions

Based on the results from the isotropic loading-unloading tests and a series of plane strain compression tests along different stress path on Toyoura sand, a couple of hardening functions respectively for shear and volumetric plastic strain for sand is introduced in the framework of double hardening elasto-plastic constitutive model. A modified form of plastic compressive strain energy, which is stress path-independent, and a volumetric yielding locus compose the compression hardening model. Another modified plastic shear strain energy, which is also stress path-independent, and a shear yielding locus compose the shear hardening model. Then, the plastic strains can be described as the sum of two independent parts. Based on the above, a double modified plastic work-hardening constitutive model for sandy soils is proposed. It is shown that, based on the direct comparisons between the results from the numerical calculation and corresponding drained plane strain compression tests on Toyoura sand, the above-proposed constitutive model could reasonably simulate the deformation and strength behavior of sand with different stress-path.