Numerical modelling of rock fall using extended DDA

The reasonable design of protective structures to mitigate the hazards from rock fall depends on the knowledge of motion behaviors of falling stones, such as the falling paths, velocities, jump heights and distances. Numerical simulation is an effective way to gain such kind of knowledge. In this paper, the discontinuous deformation analysis (DDA) is applied to rock fall analysis. In order to obtain more reliable results, the following improvements and extensions are made on the original DDA. (1) Solve the problem of block expansions due to rigid body rotation error. (2) Add the function of modeling the drag resistance from air and plants so that the velocities of falling stones obtained by simulations are good enough in agreement with those by experiments in situ. (3) Add the capability to consider energy loss due to block collisions so that the jumping heights and distances obtained by simulations are good enough in agreement with those by experiments even for the slope with very soft layer on its surface. One of application examples is presented to show that the extended DDA is very effective and useful in rock fall analysis. Therefore, the presented method is expected to be put into wide use in slop stability analysis.