Large-scale rockfall impact experiments on a RC rock-shed with a newly proposed cushion layer composed of sand and EPE

Rock-sheds are widely used to protect roads in mountainous areas. Generally, a soil cushion is placed on the rock-shed slab to distribute impact forces and absorb energy. However, thicker soil cushions lead to high dead loads and construction costs. This paper proposes a new cushion layer that includes both sand and expandable polyethylene (EPE), with the aim of reducing dead load and improving durability. Several studies are conducted. First, a newly proposed cushion layer composed of a foam material (expanded polystyrene (EPS) or EPE) and granular material (soil or sand) is introduced. The reasons for including EPE are explained. Then, uniaxial compression tests are conducted to elucidate and compare the compression performance of EPS and EPE, particularly the resilience performance. Finally, large-scale rockfall impact experiments are carried out on a reinforced concrete rock-shed with three types of cushion layers: sand, sand-EPS, or sand-EPE. The analysis and comparison of the experimental results suggest that sand-EPE is the optimal cushion layer to resist rockfall impact and protect rock-shed structures.