Inertial and kinematic interactions of bridge‐pile group subjected to liquefaction induced lateral spreading: Large‐scale shaking table experiments

Abstract

AbstractThis paper investigates the seismic bridge‐pile‐soil system failure mechanisms due to liquefaction‐induced lateral spreading. Two large‐scale shaking table tests were performed on pile groups with and without bridges in sloped liquefiable soils overlain by soil crust. The systems were subjected to a weak earthquake signal (Tabas 0.05 g) and a strong earthquake signal (Tabas 0.3 g). Their responses were recorded in terms of excess pore pressure, acceleration, and displacement time histories. The piles seismic failure mode and mechanism are described based on the obtained results. In addition, the inertial and kinematic interaction effects on the piles’ deflection were evaluated. The results demonstrated that the bridge had no significant effect on the seismic response of the pile‐soil system under weak earthquakes. Meanwhile, the test model without a bridge experienced more significant soil lateral displacement, and the saturated sand exhibited dilatant behavior, and amplified the acceleration peak response during the strong earthquake. Moreover, the liquefaction‐induced lateral spreading moved the vulnerable position of the pile group bridge system from the pier bottom to the pile head, which changed the failure mode of the pile head. The results also revealed that, compared with weak earthquake excitation, the kinematic effect was significantly enhanced, and the inertia effect was weakened during strong earthquakes. Moreover, the pile curvature during both weak and strong earthquakes was inversely proportional to the bridge inertial load.