| The Chiyu coal mine is designed to mine the No.2,3 and 4 coal seams,the No.2coal seam is selected as the protective layer for regional outburst prevention measures,the No.2 coal seam adopts the gas of the coal seam in the strip of the through strata drill hole Pre pumping coal roadway as the regional outburst prevention measure.Due to the high gas content,poor permeability of coal seam and fast attenuation of gas flow in the No.2 coal seam,the problems and disadvantages of small Gas drainage radius and long Gas drainage time of drainage borehole are caused,and the effect of conventional regional outburst prevention measures can not meet the demand of safety production.According to the characteristics of the No.2 Coal Seam in the Chiyu coal mine,adopting the technology of hydraulic punching in the floor roadway can quickly eliminate the outburst risk of outburst coal seam and effectively solve the contradiction between production and safety in the Chiyu coal mine.Hydraulic punching technology uses coal pillar or rock pillar as a safety barrier,using high-pressure water jet to rush out a large number of coal bodies and release part of gas in the coal seam,so that the coal seam can release gas pressure and gas content;at the same time,The coal body around the drill hole moves strongly towards the drill hole direction,in the process of later drainage,the gas content of the coal seam will gradually reduce,and the coal seam will gradually deform,Gradually release gas pressure and in-situ stress.With the decrease of gas content and stress,the permeability of coal seam gradually increases,which makes it easier to extract gas from coal seam and gradually eliminate the risk of outburst coal seam.Through several times of hydraulic punching,the punching technology and technical parameters suitable for the Chiyu coal mine are determined.According to the characteristics of gas occurrence in the coal lane of the No.2 coal seam,the targeted hydraulic punching measures are implemented in the C0204 floor lane,and the drilling extraction concentration,the drilling gas extraction amount and the regional verification effect are used as the basis for the evaluation of the hydraulic punching and outburst elimination effect.Through the comparison and demonstration of the above three indexes,the outburst risk of the No.2 coal seam in the Chiyu coal mine is not only solved the problem of long gas extraction time,but also optimized the layout of extraction drilling holes and increased the driving speed of coal roadway by about half,which meets the demand of safe production.Thesis has 22 pictures,19 tables,and 67 references. |
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