Mechanical Behavior of Unsaturated Masado Under Constant-Degree-of-Saturation Condition

Generally speaking, in many cases geomaterials are in unsaturated state. The mechanical properties of unsaturated soil are much more complicated than those of saturated soil. To rationally describe the mechanical properties of unsaturated soil, it is important to find out suitable state variables, such as degree of saturation and skeleton stress that determine the mechanical properties of unsaturated soil. In the existing researches of unsaturated soil, however, element tests under constant-degree-of-saturation condition is not sufficient in relating to the search of constitutive model. In this paper, degree of saturation and the skeleton stress are regarded as the state variables. Oedometer tests and triaxial compression tests under constant-degree-of-saturation condition were conducted to study the mechanical properties of unsaturated Masado (Decomposed granite) at different degrees of saturation. It is found that the degree of saturation and the skeleton stress can be reasonably used as the state variables to describe the mechanical properties of unsaturated soil in proper constitutive model.