Abstract
This study investigates liquefaction resistance of sand under sequenced earthquake motions by cyclic torsional shear tests. Two series of stress-controlled tests, “step loading” and “irregular wave loading”, have been performed. These tests consisted of two different loading phases. In the step loading tests, certain levels of excess pore pressure were first achieved by ordinary, sinusoidal wave loadings. Subsequently, the step loading, which increases cyclic shear stress ratio in steps, was applied. This was done to evaluate the shear stress level at which excess pore pressure restarts to rise in an aftershock. In the irregular wave loading tests, these loading processes were replaced by applying irregular waves based on the record in the 2011 Tohoku Earthquake. The approach in this study effectively evaluates the risk of liquefaction associated with sequenced earthquake motions.
