Mechanisms of Geo‐Stress and Gas Pressure in Coal and Gas Outburst: Insights From Particle‐Fluid Coupled Numerical Simulation

ABSTRACT With increasing mining depths, elevated geo‐stress and gas pressure substantially raise the risk of coal and gas outbursts (CGO), posing serious threats to mining safety. Conventional approaches including triaxial mechanical experiments, large‐scale physical simulations, and existing numerical models have been limited in delineating the distinct roles of geo‐stress and gas pressure during the CGO process. In this study, we developed a novel method coupling particle flow with computational fluid dynamics to unravel the underlying CGO mechanisms. Our simulations reveal that geo‐stress predominately accelerates damage via tensile and shear cracking, whereas gas pressure exerts a comparatively modest effect on crack propagation. Under coupled geo‐stress and gas pressure, the CGO failure zone evolves from a spindle‐like to a quarter‐ellipsoidal morphology. The internal stress of coal body change appears in four forms: continuous decrease, increase‐then‐decrease, continuous increase, and periodic decrease–increase. Furthermore, the increase in gas pressure and geo‐stress not only leads to higher velocity and greater quantity of outburst coal particles but also accelerates the formation of cracks, promotes earlier coal damage, and premature stress release. These findings provide mechanistic insights into the initiation and evolution of CGO, offering a quantitative basis for the design of targeted prevention strategies in deep mining.