Abstract: To investigate the influence of temperature effects on the crack evolution mechanism and failure modes of rock, a numerical model for simulating the crack evolution process in rock under thermo-mechanical coupling was proposed based on the ordinary state-based peridynamics method. The model incorporated the maximum principal stress and the Mohr-Coulomb strength criterion to determine crack propagation types. The reliability of the model in simulating material fracture behavior under thermo-mechanical coupling was verified by comparison with numerical solutions from coupled thermo-mechanical finite element method, analytical solutions for stress concentration around an orifice, and rock uniaxial compression fracture test results. Additionally, the mechanisms of temperature effect, ambient temperature, and loading rate on crack initiation and propagation in rocks were explored. The research results indicate that following pre-cooling treatment, the initiation of rock cracks occurs earlier, the propagation rate accelerates, and the peak strength diminishes by approximately 13.1%−17.2%, exhibiting a tensile-dominated failure characteristics. As the ambient temperature increases, crack propagation paths become more concentrated, peak strength improves by 3.2%−18.6%, the failure process is delayed, the development of tensile cracks is suppressed, and the failure mode gradually shifts to shear-dominated crack propagation. When the loading rate rises, the crack evolution duration is shortend. Comparing to room temperature conditions, the difference in the proportion of through-going cracks at the moment of failure under pre-cooling treatment decreases from 22.8% to only 2.95%, suggesting that higher loading rate markedly reduces the sensitivity of temperature effects to propagation.

Key words: rock, peridynamics, thermo-mechanical coupling, temperature effect, crack propagation