Experimental study of rock-sheds constructed with PE fibres and composite cushion against rockfall impacts

To improve the impact resistance of rock-sheds, polyethylene (PE) fibres and expandable polyethylene (EPE) foams are proposed for structural construction. With PE fibres added into the matrix, the ductility and the impact resistance ability of concrete can be enhanced. Moreover, to reduce the dead load and impact load, EPE foam is utilized to replace some sand layers, forming a composite cushion. A series of large-scale rockfall impact experiments were carried out on four prototype models. Under a low- and medium-impact energy, compared to the traditional sand cushion, the composite cushion was more favoured to reduce the impact loading and was more suitable to resist multiple impacts. With the addition of fibres, the integrity of the concrete matrix was improved. The fibre concrete had a better energy dissipation capacity than that of the plain concrete. In addition, more cracks occurred in the plain concrete. When subjected to high energy, the reinforced concrete model was damaged with a large deformation and many fragments. However, the maximum deformation of the PE fibre-reinforced concrete model was very small, and almost no spalling or fragments were found. These results indicate that when constructed using PE fibres and EPE foams, the capability to resist the impact loading of rock-sheds can be significantly improved.