Effect of hydrostatic pressure on geomaterials

Shear strength of geomaterials including cohesive strength and frictional strength is significantly influenced by the hydrostatic pressure. The shear strength is provided by cohesive force, frictional force between granules and the crush of granules. Roles of cohesive strength and frictional strength played under different hydrostatic pressures were analyzed, and the shear strength property influenced by the crush of granules was also studied, then the mechanism of hydrostatic pressure effect was expounded. When the material was under a low hydrostatic pressure, the mutual movement of granules resulted in the failure of geomaterials, which exhibited the shear stress ratio failure characteristics. When the material was under a high hydrostatic pressure, the crush of granules resulted in the failure of geomaterials, which exhibited the shear stress failure characteristics. The failure function in meridian plane of triaxial compression was used to revise the nonlinear unified strength model. The revised nonlinear unified strength model described not only the effect of intermediate principle stress, but also the effect of hydrostatic pressure on geomaterials more reasonably. Compared with the data from a number of true triaxial tests, the revised nonlinear unified strength model was shown to describe well the hydrostatic pressure effect and 3D nonlinear strength properties under multiaxial stress conditions of different materials. ©, 2015, Academia Sinica. All right reserved.