• Establish an elasto-plastic peridynamic model for polycrystalline rocks considering explicit representation of polycrystalline structures with diverse mineral compositions • Analyze the shear behaviors of rock joints with asperity damage in polycrystalline rock • Stochastic mineral distribution has negligible effect on shear strength under identical compositions • Higher JRC induces transition from localized to diffuse damage patterns The shear behavior of rock joints with asperity damage in polycrystalline rock is significantly influenced by grain-scale heterogeneity, a critical factor affecting the stability of underground engineering projects. While Peridynamics (PD) has been increasingly applied to analyze shear behavior of rock joints, existing models often idealize the rock as an isotropic continuum, neglecting its intrinsic microstructural heterogeneity, elastoplastic response, and detailed joint surface morphology. To address these limitations, this study proposes an elastoplastic fracture model within the PD framework to simulate the shear behavior of polycrystalline rocks. The proposed model features: (1) an explicit representation of polycrystalline structures with diverse mineral compositions, and (2) an accurate characterization of joint surface morphology using joint roughness coefficients (JRC). The model is validated through three-point bending test simulations, which show good agreement with experimental results. Direct shear tests are then simulated to systematically investigate the influences of three key factors: JRC (10.2-17.5), constant normal stiffness (0-0.01 mm), and mineral composition (plagioclase 40-60%, pyroxene 16-24%, biotite 8-12%). The results indicate that while stochastic mineral distribution has a negligible impact on shear strength of rock joints with identical compositions, an increase in plagioclase content enhances strength, and a higher JRC prompts a transition from localized to diffuse damage patterns. These findings provide valuable insights for the design and stability assessment of deep underground engineering where rock joints behavior is a governing factor for overall system performance.
Jian-zhi et al. (Thu,) studied this question.