Large Deformation Pile‐soil Interaction Under Lateral Vehicle Impact Using Hybrid SPH+FEM and EFG+FEM Models

This study presents large deformation computational methods to simulate lateral vehicular impacts on steel piles in granular soil. Soil‐mounted longitudinal barrier systems rely on energy dissipation in both the piles and the surrounding soil to safely redirect errant vehicles, so dynamic pile‐soil interaction is important for design. Conventional Updated Lagrangian finite element methods suffer from mesh distortion at large strains, which limits their use for simulating these impact events. To address this, Smoothed Particle Hydrodynamics (SPH) and Element‐Free Galerkin (EFG) formulations are coupled with finite elements to form hybrid SPH+FEM and EFG+FEM models that represent large soil deformations. The models are applied to full‐scale bogie impact tests on laterally loaded steel piles and are validated against measured energy, impulse‐time histories, and resistive force‐displacement responses. Both hybrid models reproduce the main pile behaviors, including rotation, bending, and yielding, and they capture the change in soil response from stiff resistance at small displacements to more fluid flow at large displacements. Displacement‐averaged forces and total energy are predicted within 5% to 15% of test results. The SPH+FEM model provides a more detailed description of local soil failure, whereas the EFG+FEM model was more efficient for predicting the overall system response. Because full‐scale crash tests are expensive and difficult to repeat, these validated hybrid models offer a practical tool for the design and optimization of piles in soil‐embedded barrier systems and support more reliable roadside safety design based on numerical analysis.