Development of pore water pressure in anisotropically consolidated sand under cyclic torsional loading

The development of pore water pressure plays a vital role in the evaluation of liquefaction resistance of sand. Sand in situ is typically anisotropically consolidated due to gravitational deposition and external loading. However, the influence of anisotropic consolidation stress state on the development of pore water pressure in sand has not been adequately investigated. In this study, a series of cyclic torsional shear tests were carried out using hollow cylinder apparatus for a broad range of initial anisotropic consolidation stress states and cyclic shear stress levels. The experimental results indicate that the consolidation stress-induced anisotropy leads to three different modes for the development of pore water pressure. A relationship between the pore water pressure at failure and generalized deviatoric strain is established, which enables the prediction of excess pore water pressure at failure for a broad range of anisotropic consolidation stress states. A prediction model that describes the evolution pattern of the excess pore water pressure ratio against the number of cycles is proposed. This model can capture the three different development patterns of excess pore water pressure considering the anisotropic consolidation stress state. The failure criterion defined by pore water pressure considering the influence of anisotropic consolidation is discussed.