Full-scale experimental investigation of rockfall impact on EPS geofoam-cushioned composite vertical rigid barriers

Expanded polystyrene (EPS) geofoam is a promising sacrificial cushioning material for rockfall protection, yet its full-scale performance in composite vertical rigid barriers remains insufficiently quantified. This study investigates the lateral rockfall impact response of an EPS-cushioned composite barrier through a full-scale L 9 orthogonal test program. The barrier comprised a 1.8-m-thick EPS cushion, a reinforced-concrete load-distribution slab, force-sensor assemblies, and a rigid supporting wall. Rockfall mass and EPS density were selected as nominal factors. Transmitted force and block acceleration were measured synchronously, while impact velocity, rebound, and translational kinetic-energy change were derived from high-speed video. Results revealed a clear stiffness–deformability trade-off: higher-density EPS resisted local penetration more effectively but generally produced higher peak transmitted forces and lower translational kinetic-energy loss fractions. The measured kinetic-energy loss ranged from 35.92% to 47.56% and decreased consistently with increasing EPS density within each rockfall-mass group. The system response resulted from EPS compression and crushing, lateral load spreading, and subsequent load redistribution through the RC slab. These findings demonstrate the potential of replaceable EPS geofoam as an effective frontal sacrificial layer for improving the impact-mitigation performance of composite vertical rigid rockfall barriers.