Evolutionary simulation of coupling and distribution of mining fracture-gas field of small coal pillar and thick coal seam

Mine gas represents a major hazard in coal mining. To enhance safety performance, this study investigates the dynamic coupling mechanism between mining fracture and gas fields at Yangchangwan Coal Mine, employing a multi-software coupling methodology. UDEC simulations are used to model overburden fracturing, displacement, and fracture propagation patterns during coal seam extraction, quantifying porosity distribution within the “strike three-zones” and “vertical three-zones”. Based on fracture results, ICEM CFD constructs physical models of the goaf, with FLUENT simulating gas migration patterns at different mining stages. Key findings include: ①following thick-seam mining, goaf gas exhibits fan-shaped or arc-shaped distribution, with lower concentrations near the intake airway and higher levels near the return airway. Areas distant from the coal face reach concentrations exceeding 0.75e2%VOL. ②As mining advances, fracture development height increases, enabling free buoyant diffusion of gas above the goaf. This expands gas-affected zones, forming a “Z”-shaped distribution pattern. ③During extraction with 6 m inter-panel coal pillars, gas readily accumulates on both sides of pillars, creating high-concentration “ridge-shaped” zones. This research elucidates the dynamic coupling relationship between fracture fields and gas fields during thick-seam mining, providing a theoretical basis for targeted gas control and safe production practices.