Research on Constitutive Model of Unsaturated Sand

For unsaturated sand, due to the existence of suction, under low confining pressure, it has a large volume change during shearing and obvious dilatancy and peak characteristic points appear in the whole stress-strain behavior. Based on the above situation, the boundary surface constitutive model of unsaturated sand is established in general stress space and triaxial stress space based on phase transition state and hydraulic-mechanical coupling. The model has smooth transition among different saturation state and model parameters are easily calibrated via common triaxial tests and some other simple tests.