Simulation of rock mass failure with discontinuous deformation analysis

In this paper, the application of Discontinuous Deformation Analysis (DDA), a powerful numerical method, to the simulation of rock mass failure problems has been discussed. It has been shown that the failure along discontinuous surfaces can be easily simulated by use of the method based on the Mohr-Coulomb failure criterion. For the failure (separation) of an individual block, we suggest that dense artificial meshes are made within the block, and the same strengths of the block itself are assigned to the cohesion, friction and tensile parameters of the artificial discontinuous surfaces. Then, the same algorithm as for the general discontinuities can be adopted. The new approach has been successfully applied to the simulation of a huge rock collapse at Toyohama tunnel, a very sad accident happened in Hokkaido in Feb., 1996. The collapse picture obtained from the simulation is quite in agreement with that from the spot. It is the first time that the progressive failure processes of the event are re-shown in detail. We believe that the simulation is very helpful on investigation of the failure mechanism and process, which can provide useful knowledge for preventing such kind of events in future.