摘要：Gravel cushions are widely used to absorb the impact energy of falling rocks in open-pit mines. A particularlyimportant application is to enhance the energy-absorbing capacity of rockfall sheds. In this paper, we study how varyingthe thickness and particle size of a gravel cushion influencesits energy-consumption and buffering effects. We performeda series of laboratory drop tests by dropping blocks from afixed height onto cushions of different thicknesses and particle sizes. The results indicate that, for a given impact energy,the cushion thickness has a strong influence on the measuredcoefficient of restitution (COR) and therefore impact pressure. Additional tests were performed to study how the radiusof the block and the height it is dropped from affect the measured COR. This showed that as the movement height of theblock is increased the COR also increases, and blocks withlarger radii exhibit a larger variability in measured COR. Finally, we investigated the influence of rockfall block radius,r, movement height, H, cushion thickness, h, and particlesize, d, on the COR and the damage depth, L, of the cushion.The test results reveal that the cushion thickness is the primary design parameter, controlling not only COR, but alsothe stability of the cushion material. The results provide atheoretical and practical basis for the design of gravel cushions for rockfall protection.
