Rock failure and its jointed surrounding rocks: A multi-scale grid meshing method for DDARF

• Auxiliary tool CAD is introduced to the modeling of DDARF.
• A multi-scale grid meshing method of DDARF is proposed.
• Influence on crack propagation by different lateral pressure coefficients is studied.

DDARF (Discontinuous Deformation Analysis for Rock Failure) is an improved method of DDA (Discontinuous Deformation Analysis method), while there are only uniform grids in the original DDARF, and multi-scale grid meshing method cannot be realized. A multi-scale grid meshing method for DDARF is proposed to rock failure analysis, which balances off between the calculation accuracy and computation time. Simulations with multi-scale grid model and uniform grid model are established respectively, and compared with the laboratory tests; this multi-scale grid meshing method is applied to progressive failure process for jointed surrounding rock, and influence on crack propagation by the different lateral pressure coefficients K0 of in situ stress is analyzed. It is concluded that this multi-scale grid meshing method for DDARF is feasible and the calculation accuracy can be improved with the same grid number. The proposed method is able to increase the computation efficiency by reducing the computation time when simulating underground cavern excavations, at the same time maintain the calculation accuracy. With increase of the lateral pressure coefficient K0 of in situ stress, the main cracks propagating zones are moved gradually from both sidewalls of the cavern to the arch crown and floor. This method improves the DDARF to large projects, and it can analyze the progressive failure process of rock more effectively.