Study On The Gas Drainage Technique Of SanYuan Coal Mine Roof Kilometer Directional Borehole

Gas drainage is the unique effective method of the management for mine gas disaster.The technology of gas drainage is an effective method for gas drainage in the place of the method of gas suction in the roadway,which is also the development direction of of gas control in the future.This paper is based on the 2035 working face of San Yuan's coal mine in Shanxi,and the method of combining theoretical analysis,numerical simulation and field test was applied,and the gas source and emission laws of 2305 working face was analyzed.The gas emission of 2035 working face is 36.81m³/min,and among them,the amount of this coal seam is 17.93m³/min,accounting for 48.7%of the volume of emission,and the gas emission of adjacent layer is 18.88m/min,accounting for the volume of 51.3%.The gas emission law of working face is along the tilt direction of working face,and Gas concentration gradually increased from air trough to return air trough;Along the direction of working face,the law of gas distribution is from the high to low,and then from the low to the high from the coal wall of working face to supports tail?mined out area boundary?,showing an asymmetric "V"shape.The height of the caving zone of the 2305 fully mechanized coal mining face was 16.6m and the height of fracture zone was 64.99m calculated applying the empirical formula method;simulate deformation law of overlying strata by FLAC^3D value,and both the height of the caving zone being 16 m and the height of the fracture zone being 43m were confirmed,the results of FLAC^3D numerical simulation were basically in accord with compared by using empirical formula.The fracture of the horizontal distance of 0?48m to air trough is better through the calculation of the empirical formula.The directional drilling location of roof km was ultimately determined,located in vertical height of 16m?43m and horizontal distance of air trough is 0m?48m.Drainage monitoring data displaying,the mixing amount of drainage,the pure capacity of drainage and the concentration of drainage of whole drilling field found were relatively large and the effect of drainage is better,after direction borehole gas drainage technology of roof kilometer was applied.The mixing amount of average drainage was 35 m³/min,the average pure extraction was 25m/min,and the average extraction concentration was 70%,and the extraction rate was 67%.Gas concentration of working face and the concentration of gas in upper corner were significantly decreased,the concentration of gas in corner decreased from 1.76%to 0.65%,at a huge reduction,guaranteeing the safety production of mine and to achieve the purpose of safe production.