Modeling of tunnel excavation using a hybrid DEM/BEM method

The hybrid DEM/BEM scheme is investigated in modeling tunnel excavation in an infinite or semi-infinite fractured rock mass. First, the hybrid DEM/BEM scheme is briefly described, which is very similar to the traditional hybrid FEM/BEM. In the hybrid DEM/BEM scheme, the near field is modeled by the DEM where the rock fractures can be physically introduced, and the far field by the BEM where the rock mass is treated as an equivalent continuous medium. The hybrid DEM/BEM scheme as well as the conventional model are then employed to carry out a practical case study to model an excavation of two tunnels, one above the other, in a heavily fractured rock mass. The comparison indicates that the DEM/BEM scheme can obtain a higher accuracy result with much shorter running time than the conventional model.