Hydro-mechanical Properties of Unsaturated Decomposed Granite in Triaxial Compression Test Under Drained-Vented/Undrained-Unvented Condition

Generally speaking, most of the geomaterials in surface ground are in unsaturated state. The mechanical and hydraulic properties of unsaturated soil are much more complicated than those of saturated soil. To investigate these properties, it is important to conduct systematic experiments under various conditions. In this paper, triaxial compression tests on decomposed granite under drained/undrained condition were conducted. Two kinds of special loading conditions, that is, constant suction and constant degree of saturation were adopted during shear stage. Based on the test results, it is found that the drainage of Masado specimens influence its hydro-mechanical behaviors. It is also understood that the variation of suction and degree of saturation under drained condition cannot be described by existing water retention curve models, in which the influence of deformation was not considered. The test results are also helpful for the understanding of the moisture characteristics of the decomposed granite.