A Comparison Study on the Dynamic Response of Rectangular and Circular Pile–Slab Retaining Walls Against Rockfall Impact

Abstract Pile–slab retaining wall (PSRW), as an innovative passive protection structure for mitigating rockfalls, has been extensively utilized in the western mountainous regions of China. A typical PSRW is composed of reinforced concrete piles, concrete slabs, and a soil cushion paved in front of piles and slabs. In this study, by using the LS-DYNA, a numerical model is established to evaluate the influence of the cross-sectional shape of piles on the dynamic response of the PSRW against a rockfall impact. In the numerical model, a spherical rock block of various velocities is used to impact two PSRWs of rectangular piles and circular piles. The impact force, the interaction force, the concrete stress, the concrete damage, and the displacement of piles and slabs are summarized and analyzed. The numerical results indicate that the PSRW of rectangular piles demonstrates superior impact resistance capabilities, thereby advocating for the prioritization of rectangular piles in rockfall protection endeavors. The findings of this study can give some new insights for the design of pile–slab retaining wall, especially for the choosing of pile cross-sectional shape.