Two surface elasto-plastic constitutive model for saturated sand subjected to cyclic loading

An isotropic hardening elasto-plastic constitutive model, which can evaluate the undrained cyclic behaviour of saturated sand, has been presented in a triaxial stress space. The features of the model presented are that the image point, which is related to the plastic strain vector at the current stress state, and that the physical meaning of the experimental parameters involved are clear. It is shown from the analytical investigation, 1) the shape of normal-yield surface and the parameter which is concerned with the yield characteristics can have a great influence on the undrained cyclic behaviour of sand, and 2) the model reasonably presented can evaluate the effective stress state, which the large deformation of sands happens during undrained cyclic loading.