Discrete element analyses of the dynamic response of granular soil cushion against rockfall inclined impact

This study investigates the inclined impact of rockfall onto a soil cushion covering on rock shed via a numerical model established by the discrete element method (DEM). In the numerical DEM model, the rockfall and soil cushion are mimicked as spherical particles, while the rock shed is simplified as a layer of fixed spherical particles. The numerical model is first validated and then is used to perform a series of impact tests with various impact velocities and impact angles. Based on these tests, the dependence of the impact force, transmitted force and penetration depth on the impact angle are analyzed. The corresponding results indicate that increasing the impact angle can effectively decrease the penetration depth, the normal impact force and normal transmitted force. The tangential impact force and tangential transmitted force could increase with the impact angle for the cases of the impact angle smaller than 30°. In addition, the dependence of the tangential impact force and tangential transmitted force on the impact angle is interpreted from the point of view of force chain. The proposed findings and results can give some new insights for the design of rock shed.