Numerical simulation and experimental study of methane drainage of goaf from drills along roof strike

Aiming at the problems of methane accumulation at upper corner angle in coal faces of U-type ventila-tion system, applying percolation theory, gas diffusion law and the law of mass conservation, the mathematical pattern of methane drainage from drills along roof strike was established.An analytical solution was presented by adopting explicit finite difference method.Based on Visual Basic6.0, the methane pressure field around drainage drills was obtained by SUFER software, and was also validated by the experiment on the spot.The simulation and experiment results show: (1) the method of methane drainage from drills along roof strike is effective to avoiding methane accumulation; (2) the degree and condition of roof crack are presented as the main factors affecting the drainage volume, and when the drills are disposed in cracking zone, gas drainage concentration and negative pres-sure can reach 30%~90% and 50~55 kPa respectively; (3) the numerical simulation provides an effective method in further studying of gas flow in goaf and can be taken as guidance in gas drainage and mine safety field.