A combined continuous-discontinuous approach for failure process of quasi-brittle materials

Rock, concrete and other geo-materials, due to the presence of microstructural inhomogeneity, their fracture processes and damage characteristics are associated with the distribution of micro-cracks contained in the materials. In this study, by introducing a cohesive zone model based on fracture mechanics into the framework of deformable discrete element method, a continuous-discontinuous coupling analysis approach for simulating the fracture of quasi-brittle materials is proposed. The cohesive interface elements are inserted into certain engineering or research region. It is assumed that damage and fracture occur only in the interface elements, while bulk material is modeled to be elastic. The Mohr-Coulomb criterion with tension cut-off is adopted as the damage initiation criterion, and a scalar damage variable representing damage in the material is used to describe the rate at which the material stiffness is degraded. Cracks are simulated explicitly by the failure of the interface elements. Numerical simulations are performed in order to validate the suggested method. Partial applications are also listed. The results show that this method provides a simple but effective tool for the simulation of crack initiation and propagation, and it can reflect the whole process of quasi-brittle materials from small deformation to large deformation and failure.