Liquefaction and Flowability Properties of Sand with Strain History

The liquefaction resistance and post-cyclic response of sands are influenced by prior strain histories induced by seismic loading, compaction, or other ground disturbances, which can either enhance or reduce resistance depending on the extent of prior cyclic shearing. This study investigates the liquefaction and flow behavior of sands subjected to prior cyclic strain histories using constant-volume cyclic direct simple shear (CDSS) testing. A series of staged, stress-controlled tests were performed on reconstituted Port Orford sand to evaluate how prior loading influences subsequent cyclic response. The framework integrates pore-pressure generation, strain accumulation, and apparent viscosity to characterize viscous flow behavior. The relationship between shear stress and shear strain rate under cyclic loading is analyzed using average flow coefficients and flow curves to assess the cyclic failure potential. Results reveal a consistent, strain history-independent correlation between excess pore-water pressure and viscous flow capacity, offering new insight into post-cyclic soil behavior.