A new method of cut-blasting for vertical shaft excavation and its experimental study
Based on cutting principle and technology development of vertical blasthole cut by stage and deck in vertical shaft excavation, combined with the merits of middle space charging and toe space charging, the reinforced cutting effect of central large-diameter blasthole and the method of cutting blast by stage and deck toe space charging for the vertical large-diameter blastholes was put forward and analyzed theoretically. This new cut blasting method is provided with the advantages of high blasthole using ratio, big cavity bulk, low rate of chunk, even lumpiness, and relatively high energy using ratio. The parameter choices and practical effects of this cutting method were discussed after in situ experiment. It shows that the decked delay time of 75∼100 ms is applicable.