Dangerous Region Judgment of Spontaneous Combustion in Goaf of Fully Mechanized Top Coal Caving Mining Face with Shallow Depth Seam

According to the actual conditions of No.4106 coal mining face in Anjialing No.1 Mine,a site measurement and numerical simulation combined method was applied to study the spontaneous dangerous zone in the goaf of the fully mechanized top coal caving mining face in the shallow depth seam.Based on the gas micro circulated nonlinear vadose model of the loose coal in goaf,the temperature distribution mathematical model of the loose coal in the goaf and the oxygen migration model of loose coal in the goaf,a 3D mathematical model of the oxygen concentration distribution in the goaf was established based on FLUENT.The simulation results and site measured data could be basically fitted and could provide the new technical means to accurately delimit the spontaneous combustion dangerous zone in the goaf of the fully mechanized top coal caving mining face in the shallow depth seam.Finally,according to the spontaneous combustion zone scope in the goaf,a fire prevention and control technology was conducted with the pre-buried pipe and grouted three phase foam at the top corner and the pre-buried pipe nitrogen injection alternatively.Thus the spontaneous combustion of the loose coal in the goaf of the coal mining face was effectively prevented and controlled and the safety mining of the coal mining face was protected.