A damage-based numerical manifold approach to crack propagation in rocks

Abstract

A damaged-based numerical manifold method is proposed in this paper to investigate the micro- and macro- mechanical properties of rocks. This model accounts for material heterogeneity and local material degradation using an exponential material softening law. The Mohr-Coulomb criterion with a tension cut-off is chosen as the strength criterion to capture the rock damage and fracture modes. Once the induced tensile or compressive stress in an element fulfills the criterion, this element will be damaged and a crack will initiate from the centroid of this damaged element to the centroid of its adjacent damaged manifold element. To verify the proposed damage-based numerical manifold method (NMM), a series of benchmark tests are conducted and the results are compared with the numerical manifold method incorporated with a Mohr-Coulomb criterion-based fracturing algorithm to simulate the progressive failure. The simulated results are consistent with the analytical solutions, and the advantages and disadvantages of two methods are compared and analyzed. Numerical results indicate that the proposed damage-based numerical manifold method can capture the process of crack initiation and propagation, and this method is an effective and reliable approach for modelling cracking behavior of rocks.