Study on non-centrosymmetric cracking of gas-containing rock induced by Gaussian distributed heat flux

To investigate the fracture initiation mechanism in gas-bearing rocks induced by Gaussian-distributed heat flux and associated crack air-vapor pressure, a governing equation for air-vapor pressure within cracks was formulated. Five spatial distribution models of rock fractures under Gaussian heat flux were subsequently developed. A fracture initiation criterion, based on the modified maximum tangential stress (MMTS) theory, was proposed under Gaussian heat flux conditions and validated theoretically using the finite element method (FEM). Key findings reveal that the average crack surface temperature rises with the expansion of the effective heat flux region. The spatial distribution of heat flux governs its magnitude across the crack surface, thereby dictating the formation of distinct high-temperature and low-temperature zones. Transverse heat flux q(x) predominantly drives mode I stress intensity factors (KI), controlling tensile fracture initiation, while vertical heat flux q(y) governs mode II stress intensity factors (KII±), associated with shear-dominated cracking. Both KI and KII± exhibit a positive correlation with the effective heat source radius (r0). Displacement of the heat flux induces non-centrosymmetric crack initiation, characterized by an abrupt transition in the critical crack angle from − 90° to 90°, where the transition boundary shifts proportionally with heat flux displacement magnitude. These findings provide fundamental insights into the fracture initiation behavior of gas-containing rocks under Gaussian distributed thermal loading, offering theoretical and practical implications for geothermal and rock engineering applications.