Coupled DEM-FDM analyses of the effects of falling rock’s shape and impact angle on response of granular cushion and rock shed

Rock shed is an effective protection measure against rockfall. To investigate the influences of falling rock’s shape and impact angle on the impact effect of the cushioned rock shed, a modeling approach for a rock shed with a cushion layer using PFC-FLAC. The granular cushion is modeled as an aggregate of discrete non-cohesion particles, while the concrete plate and the beam are modeled as zones. The falling rock with different sphericities and impact angles is modeled as a rigid assembly. The numerical model is validated by comparing the simulation results with experimental and numerical results from previous literature. This model is applied to analyze the effects of rock shape and impact angle on the dynamic interaction effects between falling rock and cushioned rock shed, including the impact force, transmitted bottom force, penetration depth, and plate deflection. The numerical results show that the variation in the falling rock’s shape has different effects on the falling rock with different impact angles. These findings could support rock shed design by revealing the limitations of the assumptions in the past research, which may result in unsafe rock sheds for some rockfall cases.