A DFN-DEM Multi-Scale Modeling Approach for Jointed Rock Mass

A jointed rock mass is composed of intact rock matrix and joints. Joints play an important role in influencing the strength and deformation behaviors of jointed rock masses. Based on the concept of representative elementary volume (REV) and the synthetic rock mass (SRM) modeling technique, a conceptual DFN-DEM multi-scale modeling approach is proposed. Discrete fracture networks (DFNs) are generated using MoFrac – a newly developed DFN generation tool. For a given volume of jointed rock mass, multi-scale DFN models are constructed according to the hierarchical order of fracture size. Based on the DFN models of various scales, effective rock mass properties are obtained by the homogenization method using 3DEC SRM models. A tunnel excavation modeling using data from the Äspö TAS08 tunnel is conducted to demonstrate the applicability of the proposed multiscale modeling approach. The tunnel excavation modeling results show that it is very efficient to model rock mass mechanical response using the proposed approach and a reasonably good excavation response is captured. The proposed DFN-DEM multiscale modeling approach can be used as a virtual laboratory to conduct numerical experiments to capture mechanical behaviors of jointed rock mass in a more practical manner, which can be used for stability evaluations of slopes and underground excavations in rock engineering.