Response Mechanisms of Pile-Supported Embankment Subjected to Normal Fault Rupture Using 3D Finite Element Analysis

Pile-supported embankments are widely used to improve the performance of transportation infrastructure constructed on soft soil. However, their behavior under permanent ground deformation induced by normal fault rupture remains insufficiently understood. This study investigates the response mechanisms of a pile-supported embankment subjected to normal fault rupture using three-dimensional finite element analysis. Numerical simulations were performed using Abaqus to evaluate the influence of fault outcrop location on embankment settlement, pile settlement, lateral pile displacement, axial load distribution, shear force, and bending moment response. A normal fault with a dip angle of 60° and a vertical displacement of 0.6 m was considered. Three fault outcrop propagations were analyzed, corresponding to normalized outcrop (s/B) of 0.5, 1.0, and 1.5, representing fault rupture crossing the mid portion of the piled embankment, crossing the entire piled embankment, and propagating beyond the piled embankment width, respectively. The results indicate that fault outcrop propagation significantly influences the deformation and load-transfer behavior of the piled embankment system. Embankment and pile settlements increased progressively as the fault outcrop moved from the embankment center towards and beyond the piled zone, with the s/B=1.5 case producing the largest settlement response. In contrast, the greatest lateral pile displacement, shear force, and bending moment generally occurred in the s/B=1.0 case, where the pile group was located within the primary deformation zone. Fault rupture also induced substantial axial load redistribution within the pile group, characterized by increased shaft load transfer and the mobilization of negative skin friction. The findings provide insight into fault-soil-pile interaction mechanisms and highlight the importance of considering fault outcrop location in the design and assessment of pile-supported embankments in tectonically active regions.