A novel damaged-based numerical manifold method to simulate the failure process of brittle rocks from damage evolution to crack initiation, propagation and coalescence

Abstract

In addition to macroscopic crack propagation and coalescence, the nonlinear deformation of rocks also includes mesoscopic damage buildup and transformation to macroscopic crack. To accurately model the progressive failure process of rocks, a novel damage-based numerical manifold method (NMM) is proposed in this study. The damaged-based NMM incorporates the Weibull statistical distribution, and the exponential function material softening model to describe damage evolution and strength reduction of heterogeneous material. When the damage accumulation of adjacent manifold elements satisfies the failure threshold, a real macroscopic crack is initiated from these two manifold elements, accompanied by cutting off these two manifold elements. The Mohr-Coulomb criterion with a tension cut-off was used to evaluate fracture modes of cracks. To verify the proposed method, a series of numerical tests were conducted and the numerical results were compared with laboratory experiments and other numerical results. On this basis, the effect of heterogeneity on the failure process in rock specimens with a single crack is clarified. Results from this study show that the simulations satisfactorily capture the failure process of brittle rocks from damage evolution to crack initiation, propagation, coalescence and large displacement, implying that the method is an appropriate and robust tool to model the damage and fracture behavior of rocks.