Study on forced initial caving technology of deep hole presplitting blasting in hard roof

Aiming at the problem of frame compression during the initial mining and caving under the condition of hard roof, taking Panji No.2 Coal Mine of Huainan mining area as the engineering background, by combining theoretical analysis, numerical simulation and field measurement, the determination of forced roof caving height for deep hole presplitting blasting was studied.The results show that the forced roof caving height should not be less than 10 m; in the range from 0 m to 20 m, with the increase of the roof caving height, the initial pressure step of the basic roof decreases, and the abutment pressure in front of the coal wall decreases; in the range from 20 m to 30 m, the initial pressure step and the abutment pressure do not change much, so the optimal roof caving height is determined to be 20 m.After the forced roof caving and initial mining, the support pressure monitoring shows that the initial pressure step is from 17 m to 30 m, the pressure is not violent, and the blasting effect is good.It is of reference significance for the initial mining and initial caving of working face under such conditions.