Triaxial Compression Tests on Unsaturated Decomposed Granite under Undrained-unvented condition and Its Modeling

摘要

Generally speaking, most of geomaterials in surface ground are at unsaturated state. In order to understand the mechanism of landslide or liquefaction in surface ground, it is necessary to clarify the hydromechanical properties of unsaturated soil under undrained-unvented condition. In this paper, triaxial compression tests on decomposed granite (also called as Masado) under undrained-unvented condition were conducted. Based on the test results, a modified water retention curve model was proposed, in which, the influence of deformation on water retention curve is properly considered. Corresponding element simulations were also conducted. By comparing the test and the simulated results, it is found that under undrained-unvented condition, the changing tendency of degree of saturation is totally the same with the dilatancy, while the variation of suction shows reversed tendency with the dilatancy. The modified water retention curve model can qualitatively describe the mechanical and hydraulic properties of unsaturated Masado under undrained-unvented condition. The test results are helpful for understanding the mechanical properties of Masado.