Abstract:
Under the action of multiple disturbances in the mining operation, the high stress roadway adjacent to the mining area in the comprehensive discharge face of extra-thick coal seam is often faced with the risk of dynamic disasters such as impact pressure and violent deformation of the surrounding rock, so based on the comprehensive discharge mining project of extra-thick coal seam in Chengjiazhuang Coal Mine, it is proposed to adopt the directional tension blasting roof pre-cracking technology to achieve the stress control of the surrounding rock, and the technical effect is verified through the method of combining numerical simulation and engineering measurements. The study shows that after the cantilever structure of the open area formed by comprehensive discharge mining is fractured, the step-like rock beam structure shows significant scaling effect. After the implementation of directional roof pre-cracking to the roadway of the neighboring hollow area, the load transfer between the roof plate and the coal pillar at the back of the working face was effectively weakened. Comparative field tests show that the deep directional blasting roof pre-cracking technology significantly improves the stress state of the surrounding rock in the working face end area of the extra-thick coal seam, the average value of the load of the neighboring roadway over-supporting system decreases by 11.4%, the stress extreme value of the coal pillar of the guarding roadway decreases by 13.9%, and the average displacement of the serious bottom bulge section decreases by 64.5%, so the stability of the surrounding rock is significantly improved.