Study on upper and lower gas drainage and prevention and control technology in deep mine mining high gas mine

Abstract In view of the”three high” problem of deep high gas mine mining, the rapid increase of coal seam permeability coefficient and the continuous reduction of coal and gas outburst risk gradually increase the difficulty of gas control. Taking the occurrence of long-distance outburst coal seams in zhujixi mine as the research background, this paper analyzes the gas occurrence characteristics of 11 − 2 Coal Seam and the feasibility of 11 − 2 Coal Seam as the lower protective layer by using the technical methods of theoretical analysis, calculation and numerical simulation, and studies and determines the pressure relief protection range of 11 − 2 coal seam mining to the overlying 13 − 1 coal seam; This paper puts forward the regional outburst prevention technology of underground penetrating and bedding borehole pre drainage for the protective layer and the regional outburst prevention technology of pre drainage combined with the mining surface and underground of the protected layer. Coal seam 11 − 2 has uneven gas occurrence and poor regularity. There are only high gas areas in some parts, which are greatly affected by geological structure and slate properties of coal seam top and bottom. Coal seam 11 − 2 is a stress dominated briquette and gas outburst coal seam. Zhujixi mine adopts the regional outburst prevention model of combined pumping up and down the well, that is, coal seam 11 − 2 with low outburst risk is selected as the protective layer for mining first, and coal seam 13 − 1 is protected above, At the same time, the gas in the protected layer shall be extracted. 11 − 2 Coal adopts the gas control mode of "one side with three lanes (one side with five lanes in the first mining face) and surface drilling", so as to realize multi-purpose, joint treatment and continuous mining of one lane. Comprehensive outburst prevention measures are adopted for the tunneling working face through layer drilling pre drainage and the coal mining working face along layer drilling pre drainage area. During the mining period, the surface drilling and top drainage roadway are used to extract the pressure relief gas of 13 − 1 coal, and the combined upper and lower shaft extraction area technology is adopted. In the underground excavation and mining working face, the gas concentration of return air flow, measured residual gas content and residual gas pressure are measured, The prediction indexes have not exceeded the standard, and there has been no dynamic phenomenon. In the application of outburst prevention technology in the area of up-down combined extraction in zhujixi mine, the proportion of well extraction is 56.7%, and the proportion of underground extraction is 43.3%. The maximum height of the caving zone after mining of coal face 11 − 2 is 11.6m, and the height of the fracture zone is 34.4 ~ 52.2m. The working face of protective layer 13 − 1 is arranged at the upper part of the fracture zone or the lower part of the bending subsidence zone, which can effectively increase the permeability of coal seam 13 − 1, and has no significant impact on the normal mining of coal face 13 − 1.