Abstract: Taking a fully mechanized top-coal caving face in Xiakuotan Mine as research object, the impact and friction ignition phenomenon caused by hard roof collapse and the mechanism of inducing methane burning and explosion in goaf was studied and by experimental study and theoretical analysis, and the methane distribution law and easy-burning and explosion location in goaf were simulated by using Fluent Software. The results show that the collapse impact and fiction process of hard quartz sandstone roof may produce high temperature spark, which may ignite methane within goaf and induce methane burning and explosion accident. The increased temperature of impact friction surface ΔT is positively correlated, with the mass of collapsed rock m and collapse height H, that is, value in impact friction surface will increase as and H increase. Based on distribution law of goaf methane concentration, the easy-burning and explosion area locates at upper goaf near caving face in the U-type ventilation mode, while the area may mainly distribute in middle goaf in the Y-type ventilation mode. Prevention techniques such as forced roof caving, water and inert gas injection of goaf gangue, and goaf gas drainage, etc, has been put forward.

Key words: quartz sandstone, friction spark, goaf methane, methane burning and explosion, numerical simulation