Simulation of rock slope failure with three-dimensional discontinuous deformation analysis (3D DDA)

In this paper, both the theory of Three-Dimensional Discontinuous Deformation Analysis (3D DDA), and its application to simulate rock slope failure problems are discussed. DDA belongs to one of the discontinuous numerical analysis methods, and the contact judgment and contact force computation should be concerned to produce contact forces when blocks contact to each other. It is shown that a normal contact spring is employed to calculate the normal contact forces to prevent blocks from penetrating to each other during contacts. However, the normal contact spring is deleted when blocks are leaving. In addition, the failure along discontinuous surfaces can be simulated easily by applying the Mohr-Coulomb failure criterion. The appropriate contact spring arrangement in 3D DDA follows the criterion of "No-penetration and No-Tension" to obtain correct contact forces during contacts. The new approach has been successfully applied to simulate a rock slope toppling at Amatoribashi-nishi site in Japan. The simulation results are quite in agreement with the video pictures obtained from the field. We believe that the simulation is very helpful on investigation of the failure mechanism and process, which can provide useful knowledge for study such events in future.