THE SATURATED DENSE SAND ELASTIC-PLASTIC MODEL CONSIDERING PHASE TRANSITION STATE

In the triaxial test, the dense sand is difficult to finally reach a critical state. Basing on Yu's CASM model, this paper presents an elastic-plastic model suitable to relatively dense saturated sand. The model has two aspects of improvements:firstly, the dilatancy stress ratio M_d is expressed by phase transformation state parameters, and it is introduced into a dilatancy equation; secondly, the parameters independent of stress path are used as hardening parameters to replace the plastic strain increment of a modified Cambridge model. Verified by some tests' results, the model is suitable to simulate the dilatancy of relatively dense saturated sand, and it can also reflect the hardening and softening characteristics during a shearing process. The model consists of 10 parameters that can be obtained directly from a conventional triaxial test.