Application research on roadway protection technology by hydraulic fracturing roof cutting pressure relief in underground coal mine

The gas concentration of No.8 coal seam in north 3 panel of Duerping Coal Mine is high, the direct roof and the basic roof are both hard limestone, and it is easy to form a large area of hanging roof in the upper corner after stoping on working face, which is not easy to collapse naturally in a short time, resulting in a high degree of stress concentration in the protective coal pillar of the adjacent working face. In the process of stoping of working face, floor gas drainage roadway arranged under the coal pillar is often affected by advance and lateral supporting pressure, which often results in large deformation and seriously affects ventilation and gas extraction of the roadway. Under influence of strong dynamic pressure, the floor gas drainage roadway shows intense pressure, which cannot satisfy the dual-use of one roadway. In view of the above problems, taking 68306 working face as research object, application research on roadway protection (floor gas drainage roadway) technology by hydraulic fracturing roof cutting pressure relief was carried out. The roadway protection technology by hydraulic fracturing roof cutting pressure relief was adopted on roof near the coal pillar side in air return way to cut off the connection between the roadway and the basic roof above the coal pillar, and minimize the length of side cantilever beam, weaken or transfer high stress of overlying coal pillar, reduce the load of coal pillar,so as to make 68306 floor gas drainage roadway be in a low stress area, fundamentally change the stress state of roadway surrounding rock,which achieves the effect of pressure relief and protect the roadway. The test results show that the deformation of surrounding rock of floor gas drainage roadway is obviously reduced after implementation of roadway protection technology by hydraulic fracturing roof cutting pressure relief, the deformation of the two sides and the roof and floor are controlled within 12% and 20% respectively. After using hydraulic fracturing roof cutting in air return way, the area of hanging roof in the upper corner of the working face is effectively controlled, and the gas accumulation in the upper corner is avoided.