Abstract
Dynamic centrifuge tests were performed for a four-pile group foundation model embedded in saturated fine sand layers. The test results are compared with the analytical results by the numerical model which consists of beam elements and nonlinear interaction springs taking into account the effective stress. These test and analytical results indicate that pile bending moment is affected by the acceleration level and the wave form of input earthquake motion. Pile bending moment by the inertial interaction becomes smaller corresponding to the decrease in response acceleration of the structure but reaches a deeper part of the pile in liquefied soil. Pile bending moment by the kinematic interaction becomes larger at the boundary of soil layers and its contribution to the total pile bending moment increases with input acceleration level.
