Abstract
An isotropic hardening elastoplastic constitutive model for sand is developed by extending the model for clay proposed before. This model for sand (named tij-sand model) can precisely take into consideration the influence of intermediate principal stress on the deformation and strength characteristics by using the concept of the mechanical quantity tij, and the influence of stress path on the direction of plastic flow by dividing the plastic strain increment into two components, in the same way as the previous model for clay (tij-clay model). In the present paper, a new "plastic work based on tij" W*p is defined, and it is experimentally shown that W*p is proper as the quantity of state for sand. Then, the model for sand is formulated by employing W*P as the strain hardening parameter, in place of the plastic volumetric strain ενp in the model for clay. The validities of the model are confirmed by various shear and consolidation tests under triaxial compression, triaxial extension and three different principal stresse conditions and stress probe tests under triaxial compression and extension conditions. All of the soil parameters of the model can be determined by a conventional triaxial compression test after loading-unloading-reloading isotropic consolidation.
