A nonlocal hybrid model for elasto-plastic fracture of rock-like materials

An unsolved challenge for successful simulations of rock-like materials is how to describe the entire fracture process, including the transition from elasto-plastic to strain-softening behavior and crack propagation. A novel nonlocal hybrid model (NHM) based on the Hoek-Brown criterion is proposed to characterize the combined elasto-plastic and fracture behaviors of rock-like materials. The proposed model couples the non-ordinary state-based peridynamics (NOSBPD) method and the nonlocal differential operator method to eliminate the surface effect due to the incomplete integral region near the boundary, and to simplify the imposition of boundary conditions. A plastic constitutive model with the well-known Hoek-Brown criterion is integrated within this framework to accurately represent the nonlinear behavior of rock-like materials. Strain-softening and fracture criteria, based on the equivalent plastic strain, capture the elastoplastic response and damage-fracture processes in rock. The dynamic relaxation method is combined with the return mapping method to address quasi-static nonlinear problems. The proposed model is verified by comparing its results with those from the Finite Element Method (FEM), as well as with experimental data from the literature. Numerical examples demonstrate that the proposed model captures well the entire elasto-plastic fracture process for rock-like materials, including elasto-plastic deformations, crack propagation and progressive failure.