Impact resistance performance and optimization of the sand-EPE composite cushion in rock sheds

Rock sheds are widely used to prevent rockfall disasters along roads in mountainous areas. To improve the capacity of rock sheds for resisting rockfall impact, a sand and expandable polyethylene (EPE) composite cushion was proposed. A series of model experiments of rockfall impact on rock sheds were conducted, and the buried depth of the EPE foam board in the sand layer was considered. The impact load and dynamic response of the rock shed were investigated. The results show that the maximum impact load and dynamic response of the rock shed roof are all significantly less than those of the sand cushion. Moreover, as the distance between the EPE foam board and rock shed roof decreases, the maximum rockfall impact force and impact pressure gradually decrease, and the maximum displacement, acceleration and strain of the rock shed first decrease and then change little. In addition, the vibration acceleration and vertical displacement of the rock shed roof decrease from the centre to the edge and decrease faster along the longitudinal direction than that along the transverse direction. In conclusion, the buffering effect of the sand-EPE composite cushion is better than that of the pure sand cushion, and the EPE foam board at a depth of 1/3 the thickness of the sand layer is appropriate.