Application of NMM-DDA to earthquake induced slope failure and landslide

Discontinuous Deformation Analysis (DDA) and Numerical Manifold Method (NMM) have been used for the analyses of discontinuous rock masses. For the dynamic response analysis of rock slopes, it is necessary to consider the local variation of seismic forces, especially when the slope size is large and/or the slope geometry becomes complicated. In DDA, there is difficulty to consider the local displacements and stress condition in a block. On the other hand, NMM can simulate both continuous and discontinuous deformation of the block systems. However, the rigid body rotation of blocks cannot be treated properly because NMM does not deal with the rigid body rotation in explicit form. According to the above-mentioned reasons, it is reasonable to combine DDA and NMM from practical point of view. In this paper, the formulation of the coupled NMM and DDA (NMM-DDA) was presented. Since the processes to establish the equilibrium equations (minimizing potential energy) and kinematics of block system are same between DDA and NMM, these two can be combined easily by choosing displacements of the DDA blocks and NMM cover nodes as unknowns. Some applications of the NMM-DDA to earthquake response analysis of the rock slope were presented.