Research on the buffering measure of rock shed against the impact of dry granular flow with concern of structure damage

Dry granular flow induced by rock collapses and landslides is a typical disaster in mountainous areas. Rock sheds are widely used as protective structures to shield traffic lines against the impacts of rockfall, collapse, and dry granular flow in mountainous areas. However, there are few studies on the buffering mechanism of the rock shed cushion and the damage to the rock shed structure. In this paper, the buffering effect of different rock shed cushions and the damage of a rock shed due to the impact of a granular flow were further explored through numerical simulations. Three kinds of cushion conditions, i.e., an EPS cushion, a sand cushion, and an EPS-sand mixed cushion, were designed to investigate the buffering effect of the cushion layer with three impact distances. The variations in the impact force, bending moment, shear force, axial force, and energy absorbed by the rock shed were quantitatively analyzed. The cushion layers effectively absorbed the energy of the dry granular flow impact and reduced the internal force of the rock shed, thereby improving the safety of the rock shed structure. From the perspective of the comprehensive protection effect, the EPS cushion was the best among the three cushions, which may shed light on the structural design of the rock shed. Furthermore, the variation in the yield area of the rock shed was studied, and the acceleration of the rock shed structure was monitored during the impact of granular flow. The acceleration was integrated to obtain the displacement. A damage analysis method was proposed based on the relationship between the yield area ratio and the displacement of the rock shed structure. This method can be used for the rapid assessment of structural safety and provide a new approach for the safety monitoring of rock shed structures in engineering applications.