Influence of sloping ground conditions on cyclic liquefaction behavior of sand under simple shear loading

An experimental program of undrained cyclic simple shear tests was undertaken on Ticino sand, covering a broad range of initial relative densities and static stress levels, to investigate the effect of an initial static shear stress on failure mechanism, cyclic resistance, and pore water pressure generation. The results indicated that two types of failure mechanisms occurred, namely cyclic mobility and plastic strain accumulation, depending on the magnitude of the initial static shear stress with respect to the applied cyclic shear stress. Test results showed that the cyclic resistance of Ticino sand may either increase or decrease with an increasing initial static shear stress depending on the density state of the sand. The Kα correction factors measured under cyclic simple shear loading were compared with the values reported in the literature based on both cyclic triaxial and simple shear tests, suggesting that Kα could be dependent on the particle gradations and grain shape for a given depositional mechanism. Finally, it was verified that the initial static shear stress has a remarkable impact on the development of cyclic pore-water pressures (PWP) of the sands so that a modified PWP generation model has been effectively proposed in the present study