Research On Reasonable Place Of Kilometer Drilling In Lower Slice Of Extremely Thick Seam In Tingnan Coal Mine

Gas is one of the main causes factors in coal mining frequent accidents, root of gas disaster management and mining environmentally is gas drainage in mine safety production of China.Pressure relief gas in lower slice will rush into goaf of upper slice through cracks when thick and high-gas seam was mined being adopted layer mining, which causes gas in working face of upper slice going transfinite frequently.Gas extraction in high gassy seam meets a serious challenge as the drill hole cannot reach the requirement in drainage pressure relief gas in lower slice.From the perspective of controlling pressure relief gas in lower slice, based on the pressure relieved and fluid increased effect of lower slice under the condition of mining pressure when upper slice was mined, article studies about gas extraction with kilometer drilling in lower slice under the background of 205 working face in Tingnan mine, and defines maximum plastic failure depth in lower slice is approximately 13m by adopting theoretical calculation and FLAC3D numerical simulation.Based on movement of plastic distortion in different depths of lower slice, article defined the optimal layout region of kilometer directional drilling defined is 6-9m. And more drill holes should be arranged in 15～45m of two gateways along inclination of working face in that region. Gas drainage parameter of kilometer drilling in different positions in the process of working face advancing is analyzed through field experiment. It shows that drill holes in that region are not be destroyed, long-time and high concentration of gas extraction in lower slice of thick and high-gas seams is realized,drainage effect is perfect, a reasonable, simple, efficient and fresh way of gas control will be provided in thick and high-gas seams.