Study on the reasonable stratum of high-drainage roadway with roof strike of fully-mechanized working face in Sijiazhuang Mine

The gas emission of No.15106 working face of Sijiazhuang Mine of Yangquan Coal Group is relatively large and has outburst hazard. Aiming at the problem that gas at the upper corner of the working face is easy to exceed the limit, based on the "O" ring theory of overburden failure on the working face, a method of arranging high-drainage roadways on the roof along the strike for gas drainage is proposed. In order to explore the best area of layout of high-drainage roadways, first of all, theoretical calculations and material similarity simulation methods are used to obtain that the height of goaf zone is 0～20 m and the height of fracture zone is 20～60 m, the height of bending subsidence zone is more than 60 m. The range of “O” ring separated layer fracture zone on the mining side is 0～20 m.Along strike direction, the fracture angle of the open cut side is basically stable at 60°, and the fracture angle of the stoping side is 43°～68°with an average of 55°, when the advancing distance of the working face is the same as the length, the breaking angle of the inlet and return air roadways along the inclined direction are both 58°.Fluent software is used to simulate the extraction effect when the vertical distance between the high drainage roadway and the coal roof is 20, 30, 40 m, and the staggered distance from the return airway is 30, 40, 50 m. The results show that when the vertical distance of the high extraction roadway is 30 m, and the horizontal distance is 40 m, the gas volume fraction in the high-drawing lane is the highest, 21.2%, and the upper corner gas volume fraction is the lowest, 0.54%.. After the program obtained from the test is applied to field practice, in the early stage of mining, the gas volume fraction in the upper corner has the risk of exceeding the limit due to the large fissures that have not yet formed. With the advance of the working face, the amount of gas discharged by the air will gradually decrease, and the amount of gas extracted by the high extraction roadway will gradually increase. After entering the normal extraction period, the average value of gas concentration in the upper corner is about 0.6%, which is basically consistent with the simulation results. The scheme can greatly relieve the pressure of air exhaust gas and effectively solve the problem of gas overrun at the upper corner