Abstract: Research on the trajectory of rockfall is the key to the design of rockfall interception system and is directly related to the success or failure of the rockfall interception system. In this paper, the characteristics of rockfall trajectory are examined via the rockfall particle model and the ANSYS/LS-DYNA element method as comparative study. The deflection angle at the point of slope gradient change between the two methods are compared. Research findings suggest that the trajectory (including bounce height and motion distance at slope change point) of particle model in which the shape and size are neglected is larger than that in the numerical model. Designing the interception and protection system based on the results of particle model will give rise to high engineering cost; moreover, for a single typical rolling stone, the particle model can only roughly reflect the trend of motion of the falling rock. Instead, the finite element results can truly reflect the motion attitude of different shapes of rockfalls in the spatial range under the influence of slope's micro-geomorphology; it can also extract the characteristic parameters of rockfall movement at any time, which is closer to the actual engineering situation. Therefore, the dynamic finite element method is more suitable for the prediction of rockfall trajectory. The research results can provide guidance for the prevention and control of rockfall disasters.

Key words: rolling stone, motion trajectory, particle model, ANSYS/LS-DYNA, point of slope gradient change