Study On Gas Migration For Extreme Close Range Upper Protective Coal Seam Exploitation In No.5 Mine, Pingdingshan

Abstract Protective coal seam exploitation is the most economical, safe and efficient exploited technology to a coal seam which is prone to incur a coal and gas outburst. In this thesis, through an observation on the strata movement, analyzed the rule of strata movement at stress'disposal, discussed the crack increasing disciplinarian in strata movement, studied the gas emission law in different crack circumstances, got an equation described a rule of attenuation of gas coming from a dill, set up a mathematic model which is suitability for gas loss calculation for F16,17 coal seam, explored the rule of gas infiltration flow from coal wall in tunnel initiatively. It was found that about 60.1 percent of gas was come from F16,17 coal seam in the coal drift of F15-23190, and about 7 percent of gas was the gas emission from coal wall in the coal drift, though much gas came from F16,17 coal seam was closed in the goaf. Because of high gas content in F16,17 coal seam, in order to relieve the burden of mine ventilating, and utilize gas well and adequately, designed a gas drainage system in F15-23220 working face, got a ideal purpose.When studied the excavation technologies on extreme close range upper protective coal seam, found that the thickness and mechanical properties of the rock stratum control gas current and diffusion in coal, and different gas-geology conditions, gas drainage means and exploitation ways determine the excavated effects directly. Through protective coal seam excavating, gas content in F16,17 coal seam losses about 78.5 percent, gas press isn't more than 0.5MPa, and the gas permeability coefficient of F16,17 coal seam was nearly 150 times as much as before. Each safe technology index mark was under a tolerance level, the effect of gas release in F16,17 is distinctly, all above certified the practical significance.