Numerical simulation on the impact characteristics between rockfalls of different shapes and gravel cushions

The shape of rockfalls significantly affects the performance of the impact cushion, which is manifested by the difference in the impact force and the penetration depth of the rockfall during the collision. In this study, we built the collision numerical model between rockfalls and cushions based on the results from previous studies, and simulated the collision process of rockfalls with four different shapes (cylindrical, cuboid, spherical, and cubic) and different cushions. Essential parameters when rockfalls impact cushions are calculated, including the maximum impact forces on the surface and bottom of the cushions and the maximum penetration depth of the rockfall. The results showed that the maximum impact force on the surface and the bottom of the cushions varies with the rockfall shapes. The maximum impact force on the cushion surface caused by cylindrical rockfall is the smallest, followed by the cuboid rockfall, the cube rockfall, and the spherical rockfall. The maximum impact force at the cushion bottom also follows this trend. However, the penetration depth of cuboid rockfall is the smallest, followed by the cylindrical rockfall, the cubic rockfall, and the spherical rockfall. The results of this study provide more extensive theoretical support for rockfall disaster prevention using gravel cushions.