Study On Gas Drainage Technology Of High Directional Long Holes In ?8221 Working Face Of Taoyuan Mine

With the increasing mining intensity and mining depth of coal mines,the amount of gas emission from the working face is also increasing.A large part of this is from the goaf.Therefore,strengthening the control of gas in the goaf is a guarantee for fully mechanized caving.The first priority of safe recovery.In this paper,the working face of Taoyuan Mine II8221 is taken as the test object.Facing the high concentration gas in the goaf of the working face,it is proposed to adopt high-efficiency directional drilling method,which is an efficient hole-forming technology method.At the same time,this paper also systematically studies the gas emission and its migration law in the goaf.According to the source-source prediction method,the gas emission in the goaf accounts for 60.5%of the total gas emission from the working face,while the coal and coal wall gas consumption only accounts for 39.5%.Finally,by analyzing the migration law of gas in the goaf,the reason for the over-limit of gas concentration in the upper corner is revealed,which provides a theoretical basis for the directional long borehole extraction of gas in the goaf.The key to successfully reduce the gas concentration in the goaf is the rational design of the hole level.The UDEC numerical simulation software is used to simulate the rock movement in the overlying strata of the II8221 working face.The simulation results,together with the empirical formula test,show that the height of the falling belt is 0~8m,and the height of the crack belt is 8~28m.It provides scientific guidance for the arrangement of the final hole horizons in the wind tunnel.Finally,through the on-site inspection of the actual working surface and the mastery of the high-level directional long hole drilling technology method,a set of gas control schemes corresponding to the mining face was designed.The Taoyuan Mine II8221 working face is 12~16m above the 82 coal seam.A total of 5 roof high-position long-distance large-diameter directional boreholes were designed and constructed in the height range.The maximum hole depth of 3#holes is 957m,and the total footage of each hole is 4065m(including branch holes).During the 86-day monitoring period of the entire drilling site,the accumulated gas volume of the 5-hole cumulative extraction exceeded 680,000 m~3.In the process of gas drainage,the gas concentration in the return air passage of the working face did not exceed 0.3%,effectively preventing the occurrence of gas accidents.Figure[41]table[8]reference[86]...