Study on Application of Deep Borehole Pre-Fracturing Blasting Technology to Seam Opening in Mine Shaft

According to a long period to sink through a low permeability and outburst seam during a mine shaft sinking in Huainan Mining Area and the mining and excavation connection highly restricted problems,a new method of the deep borehole pre-fracturing blasting was provided to improve the seam permeability,to improve t he seam gas drainage rate and to reduce the seam opening time of the mine shaft sinking.The paper had a study mainly on the function mechanism of the seam perme ability improvement and the outburst prevention with the deep borehole pre-fracturing blasting.The paper had a simulation and analysis on the blasting with a loosing ra dius of 4 m in No.13-1 seam of No.2 Mine Auiliary Shaft in the mine and the borehole pattern plan to open the seam in the mine shaft was optimally designed.The site i nvestigation showed that after the deep borehole pre-fracturing blasting conducted for the seam permeability improvement,the gas drainage pure volume was increased by 4 times than before the blasting conducted,the seam gas drainage rate was improved and thus the 13-1 seam opening time of the mine shaft sinking was reduced by 32 days.