Constitutive model simulation for mechanical response of anisotropic sand under different principal stress directions

Rising ground water level reduces the mean effective stress within ground soil and may cause stability problems for the slopes in saturated loose sand. The constant shear drained (CSD) stress path represents the stress conditions with rising phreatic surface, yet the influences of anisotropy on soil response under such stress path are still unclear. In this study, the anisotropic CycLiq model is used to simulate the CSD stress tests under different principal stress directions. Based on the original CycLiq model, the model considers the evolution of fabric anisotropy and its influences on plastic modulus and dilatancy, and can simulate the influences of different principal stress directions. The simulated results achieve good agreement with the test results for undrained shear and CSD loading under different intermediate stress coefficients and principal stress directions. For the CSD tests, the mean effective stress in instability state is observed to increase with the increasing void ratio and loading angle. The initial fabric norm is shown to have significant influences on the stress ratio at the instability state in the CSD tests.