Effects of Soil Crust on Seismic Failure Behavior of Pile Group–Bridge System during Liquefaction-Induced Lateral Spreading: Large-Scale Shake Table Experiments

Abstract

Two large-scale shake table experiments were conducted to study the seismic pile group–bridge soil system failure mechanisms and examine the role of soil crust in lateral spreading caused by liquefaction. Pile group–bridge systems were supported by two different ground profiles, inclined liquefiable soils with and without soil crusts. The test results are discussed in terms of soil acceleration, pore pressure ratio, and displacement response. In addition, the pile seismic failure mechanisms are depicted according to the acquired date, and the effects of kinematic and inertial interaction on the curvature of pile and pier are evaluated. It was found that during weak earthquakes, the crust did not have an apparent influence on the system response. However, during strong earthquakes, the soil bed without crust experienced larger lateral permanent displacement because the shallow soil showed dilatant response and triggered spikes in acceleration. Meanwhile, the soil bed with crust restrained the lateral bridge displacement. In addition, the lateral spreading caused by liquefaction transferred the damaged position of the pile group–bridge system from the pier bottom to the pile at the bottom of liquefied soil, while the crust shifted the damaged position from the bottom of the liquefiable soil to the top of pile. The results also revealed that the crust weakened the kinematic interaction on curvature at the pile head but enhanced the inertia effect during the strong earthquake, while the opposite was true for ground without crust; the kinematic interaction was stronger, and the inertia interaction was diminished.