BOUNDING SURFACE PLASTICITY MODEL FOR SANDS.

Using bounding surface plasticity, a constitutive equation is constructed to simulate the nonlinear behaviors of loose and dense sands subjected to various types of loadings. The critical state, which depends upon the initial void ratio in the case of sands, defines the evolution of the bounding surface during plastic flow. The model describes strain-softening and stress-dilatancy with nine material constants calculated from the results of conventional triaxial tests. After comparison of experimental results with numerical simulations, the effective stress model is found to be capable of simulating drained and undrained responses, hysteretic energy dissipation, and accumulation of irreversible strain during cyclic laboratory tests. The model can be applied to study the engineering problems associated with sand liquefaction.