Loading Effects on Rock Shed by Three Dimensional Rockfall Simulation

Rockfall disasters occurred frequently in Taiwan mountain areas during the earthquake and storm events. The magnitudes of impact force on civil engineering structures depend significantly on the total rockfall volumes and the evolution of rockfall processes. Simultaneous fall of a larger rock block containing many fragments will transfer larger impact force on the rock shed than that of rock blocks with fragments gradually fall down in series. Most studies applied the Lumped Mass Approach (LMA) and two dimensional Discrete Element Method (DEM) to simulate trajectories and velocity of the rockfall movements. However, previous work often neglected that the interaction between fragments of a large falling block will cause fragments collisions and spreading, which will influence the concentration of impact force and the three dimensional effects of deposit pattern of rockfall. Therefore, this research focus on the impact force on the rock shed with varied evolution of rockfall processes. Numerical DEM program (PFC3D 3.0) calibrated with small scale physical rockfall experiment are used to simulate impact forces on rockfall shed and talus deposits. Subsequently, the valid numerical method is applied to full scale problem. The results are helpful for developing reasonable and scientifically sound base for technical code of rockfall problem.