Energy-based evaluation of seismic liquefaction response of sand in level and sloping ground

抄録

In this study, the effects of sustained initial shear stress and cyclic stress amplitude on loose sand liquefaction potential in undrained cyclic simple shear tests are evaluated using an energy-based approach. The testing results demonstrate that various stress conditions lead to two deformation patterns, namely cyclic mobility and plastic strain accumulation. The accumulated strain energy is calculated by the stress-strain hysteresis loop during loading cycle. A different pattern of dissipated energy during cyclic loading is observed for the two failure modes, with a clear tendency of dissipated energy to increase less rapidly as lower cyclic stress amplitudes are applied for all samples. The dissipated energy at failure is found to be practically independent of the cyclic stress amplitude, and it is little influenced by initial static shear stress. For a given static shear stress level, a power law-based model is established for the pore pressure build-up prediction using dissipated energy. A decreasing trend of the ultimate pore water pressure ratio values with the increase of sustained shear stress is apparent. When the residual pore water pressure ratio normalised by its ultimate value is plotted against the dissipated energy normalised by the corresponding value at failure, data points fall in a narrow band regardless of various static and cyclic shear stresses.