Research and application of high-level long drilling blasting technology for preventing and controlling rock burst

Existing technology have constraints in mitigating frequent rock burst of mining under high-level thick and hard roof in a mine, Shaanxi, du to direct weakening of the whole layer in the underground. Here, a rock burst prevention and control technology of thick and hard roof by long borehole blasting in high drilling field is proposed. With theoretical analysis and numerical simulation, its mechanism of pressure relief and load reduction effect is analyzed, its layout parameters and targeted layers are determined, and finally field trial is carried out in 2412 working face of a mine. The results show that the long-distance borehole blasting technology realizes the pre-splitting of the whole layer of thick and hard roof by arranging the drilling field in the high-level roof to achieve the purpose of pressure relief and load reduction. By orthogonal experiment, the blasting horizon was identified as the main controlling factor of the pressure relief effect of long-distance borehole blasting. Roof stratum at 52-67 m above 2412 working face is the main hazard-causing layer and determined as the blasting horizon. According to the periodic weighting interval during the mining period of the working face and the fracture development radius of the blasting in surrounding rock, the hole spacing is determined to be 30 m. The engineering practice shows that the frequency, energy of microseismic events and the deformation of roadway after long-distance borehole blasting are reduced. Compared with the traditional roof deep hole blasting technology, the long-distance borehole blasting technology covers a larger pressure relief range and a more significant pressure relief effect. The research conclusion can be used to reduce the load and pressure of the high-level thick and hard roof for mining under similar conditions.