Study on support of retractable channel in fully-mechanized mining face with super large mining height

In order to realize the safe and efficient retraction of large-scale equipment in the 8.2 m super-high mining height working face in Yushen Mining Area, taking the retraction roadway of the No.12-2108 working face of Jinjitan Coal Mine as the engineering background, the methods of theoretical calculation, numerical simulation, and on-site mining pressure measurement were used to study the law of the basic top period of the working face during the last mining phase and the roof fracture position, it is concluded that the basic top period of the step distance is about 19.3 m in the final mining stage. The working pressure is severely affected by the dynamic pressure when the face advances 7.9 m from the main retraction roadway and the pressure is terminated at 2 m before roadway the drive-through. The isobaric technology of stopping mining is used to prove that the working face and the retraction roadway are connected without equal pressure. At the same time, it is determined that the location of the first cycle to pressure fracture is located at about 4.8 m in the coal pillar in the middle of the main and auxiliary retraction roadways, and the working face finally achieved drive-through without pressure. Based on the above mining pressure analysis and coal seam occurrence conditions, the retraction roadway innovatively proposes a new design method of using constant resistance large deformation anchor cable + steel strip cross link to support the overall stress zones of the A, B, and C. The actual measurement application shows: The anchor cable elongation in area C is greater than that in areas B and A. The closer the side of the working surface is, the greater the anchor cable subsidence is. The maximum extension of the constant resistance anchor cable located in the middle of the retraction roadway (C area) near the mining side reaches 180mm. After the stacking support is withdrawn, one side of the large-section roadway becomes a cantilever beam. At this time, the constant resistance and large deformation anchor cable is completely stressed, and the roof of the retraction roadway is inclined to the gob as a whole, which proves the constant resistance during the withdrawal of the support. The anchor cable can maintain the temporary stability of the roof, which ensures that the roof does not fall out, the bottom plate, corners and corners are basically not deformed, and the surrounding rock control effect of the retraction channel is very good. The 8.2m fully mechanized mining support completed the overall withdrawal of the equipment in 12 days, realizing the safe and efficient retraction of the fully mechanized mining equipment with super large mining height, and providing a reliable reference for similar mines.