Effect of initial static shear stress and cyclic loading direction on the liquefaction behavior of saturated dense sand

Soil unit of a sloping ground under seismic loading with initial static shear stress and cyclic loading, which has different direction respectively. To investigate the effect of the direction between initial static shear stress and cyclic loading on saturated dense sand, a series of consolidated undrained multidirectional cyclic simple shear tests for saturated dense sand had been completed. The study results show as follows. These main failure types of saturated dense sand are cyclic mobility and accumulated plastic strain which effected by initial static shear stress value. Initial static shear stress will decrease liquefaction resistance of saturated dense sand, but liquefaction resistance under perpendicular loading mode is 5%~7% higher than under parallel loading mode. In different loading mode, accumulation rate of the energy dissipation increases as initial static shear stress increasing, the energy dissipation accumulation rate increasing under initial static shear stress is the internal reason which leads to liquefaction resistance decrease of saturated dense sand. The normalized curve between residual pore pressure and the energy dissipation of saturated dense sand emerges a linear correlation under logarithmic coordinates.