Optimizing the Key Parameters of Roof Cutting in Gob−side Entry Driving

The Western Transportation Roadway in the eighth mining area of Jingfang Coal Mine is a gob−side entry driving roadway with a buried depth of about 420 meters. The protective coal pillar of Western Transportation Roadway undertakes lots of load, and the roadway is easily destabilized. In order to effectively solve the above problems, taking the Western Transportation Roadway as the engineering background, the calculation models of roof cutting parameters were established, and the reasonable range of cutting height and angle were theoretically calculated, the results show that the roof cutting height is in the range of 14~32 meters, and the minimum roof cutting angle is 9°. FLAC^3D numerical simulation software was used to establish three−dimensional simulation calculation mechanical models, and the variation law of stress and displacement of roadway surrounding rock under different roof cutting height and roof cutting angle were compared and analyzed. The results show that cutting the roof above the coal pillar can not only reduce the concentrated stress of the coal pillar, but also reduce the load borne by the coal pillar of the roadway, block the lateral abutment pressure of the goaf to the roadway, and reduce the deformation of the roadway. There is an optimal roof cutting scheme for hard roof cutting and pressure relief to achieve the best pressure relief effect. The optimal roof cutting height of the western transportation roadway in the eighth mining area of Jingfang Coal Mine is 25 meters, and the roof cutting angle is 26°. Under this parameter, the maximum vertical stress of the coal pillar is 24.2 MPa, the convergence of the two sides of the roadway is 0.28 meter, and the convergence of the roof and the floor is 0.17 m.