Study On The Technique Of Gas Drainage In Pressure Releasing About Steeply-inclined Thick Coal Seam

In the process of pressure relief mining coal seam, the coal seam will release pressure and become a pressure relief area. The relief area will produce a lot of new fractures and gap, make the coal expansion deformation, increase the permeability of the coal seam. Provide the channel for the gas in the coal and improving the anti-reflection of coal for the gas extraction.The main line of this paper is the relief pressure gas extraction, pressure relief gas extraction technology was studied in steeply inclined thick coal seam.Firstly, In this paper, gas migration rule of mining under pressure relief mining coal seam;the influence factors of coal seam permeability characteristics;load stress characteristics of coal and the laws of the gas collection in pressure relief mining coal seam were studied.Provide the theory basis for experiment and research for the pressure relief gas extraction technology later.Secondly,taking coal sample for the Zhongdacao coal seam, then making the standard coal samples(50mm × 100mm).The uniaxial compression test,conventional triaxial compression test, conventional triaxial compressiontest of coal containing gas, and unloading confining pressure tests of coal containing gas were be studied by WYS-800 Microcomputer-controlled electro-hydraulic servo triaxial gas seepage test device which is made in Taiyuan university of technology.The test results are uniaxial compressive peak uniaxial compressive strength of 6.54 MPa, the elastic modulus is 1196.86 MPa,the poisson’s ratio is 0.336;Conventional triaxial experiments under axial strain is1.21%, the peak peak volume strain is 0.05%, the peak strength is 103.45 MPa,the elastic modulus is 9539 MPa, poisson’s ratio is 0.26.Then the path of conventional triaxial and unloading confining pressure of coal containing gas permeation properties was studied.Thirdly, simulating the process of steeply inclined thick coal seam mining by the FLAC 3D simulation software,the stress distribution law of two layers of coal and the displacement change regularity of roof and floor were simulated.Through calculating formula to calculate the expansion of coal face plate and eight feet of coal or rock expansion deformation of coal seam 3 d cloud, found coal face plate and eight feet of coal or rock seams due to upper middle groove seam mining and achieved very good pressure relief effect, it will make coal face plate and eight feet of coal seam gas in through a crack in the roof space seepage to the large tank in the goaf, increased the content of gas in goaf.Finally, DaHuangShan Zhongdacao seam slicing process are studied,according to the characteristics of working face floor coal mining drainage, andthe face in the process of mining goaf bottom pressure relief area of the gas extraction, in order to realize the replacement of working face of drainage gas.The measured data is obtained, the residual gas pressure is 0.21 MPa,replace working face coal seam remnant gas content is 2.873 m3/ t, resolves the gas volume is 0.563 m3/ t, which can determine the area within the scope of the gas extraction effect.