Dynamic analysis of rockfall impact on a protective structure via FEM-DEM coupling

Abstract

Rockfall is one of the most catastrophic hazards among natural calamities. The issue involving rockfall protection responses of discrete-continuum interactions still remains unclear. This study innovatively couples the finite element method with the discrete element method (FEM-DEM) to realize rock block impact motion simulations and the corresponding impact loading transmitted from the gravel cushion to the concrete body. The FEM-DEM coupling algorithm is elucidated. The coupling approach is verified by a block free-fall experiment. The velocity and size effects on block impact behavior and gravel motion are investigated. Insights into interactions within the gravel cushion and the resulting concrete structure deformation are provided. Structural responses correlated with the block size and velocity effect are analyzed. The numerical results indicate that the block size and the impact velocity affect the variations in the rotational velocity and rotation-translation energy ratio of the block, respectively. Bulk material strengthening is observed at the bottom of the cushion layer. The coupling results reflect that the stress concentrations are mainly focused on the upper side of the retaining wall and the inner side of the pile root, and the structure's deformation meets the need.