Study and Application of Gob-Side Entry Retaining Formed by Roof Cutting and Pressure Relief in Medium-Thickness Coal Seam with Hard Roof

The technology of gob-side entry retaining by roof cutting can release mining pressure and reduce the deformation of roadway surrounding rock. In order to solve the problem of the hard roof of the Baoshan Coal Mine being under intense pressure and the effect of the retaining roadway being poor, a field test of directional presplitting blasting for the hard roof of the 6302 working face was carried out for the first time. Firstly, in order to determine the key parameters of roof presplitting blasting, the corresponding mechanical model was established, and the key parameters of presplitting blasting were determined by theoretical analysis. Then, based on the engineering geological conditions of the Baoshan Coal Mine, the results of the theoretical analysis were evaluated by a numerical simulation method, and the optimal cutting parameters of the 6302 working face were determined. Finally, field engineering tests were carried out at the haulage roadway of the 6302 working face of the Baoshan Coal Mine, and the good effect of the retaining roadway verified the scientific validity of roof cutting and pressure relief technology. It was found that the presplitting height of the haulage roadway of the 6302 working face in the Baoshan Coal Mine was 6 m, the presplitting angle was 15 degrees, the stress path between the goaf roof and the retaining roadway roof was effectively cut off, the process of gangue caving and compaction was accelerated, and the maximum convergence between the roadway roof and floor was monitored to reduce to 175 mm. Therefore, the application effect of gob-side entry retaining formed by roof cutting and pressure relief is remarkable for reducing the deformation of roadway surrounding rock.