高位长钻孔爆破防治冲击地压技术研究及应用
Research and application of high-level long drilling blasting technology for preventing and controlling rock burst
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摘要: 针对陕西某矿赋存高位厚硬顶板, 已有技术难以实现井下直接整层弱化导致冲击地压频发的难题, 提出一种高位钻场长钻孔爆破厚硬顶板防治冲击地压技术。采用理论分析、数值模拟等研究方法, 分析了该技术卸压降载机制, 确定了其布置参数与层位, 并在该矿2412工作面开展了工程实践。结果表明: 长距离钻孔爆破技术是通过在高层位顶板布置钻场实现厚硬顶板整层预裂, 达到卸压降载的目的; 设计正交试验确定了长距离钻孔爆破卸压效果的主控影响因素为爆破层位; 根据煤矿覆岩主控诱灾层位识别方法, 判定2412工作面煤层上方52~67 m处为爆破层位, 根据工作面开采期间周期来压步距及爆破围岩裂隙发育半径, 确定炮孔间距为30 m。工程实践表明, 施工长距离钻孔爆破后微震事件频次及能量均有所降低, 巷道变形量减小, 与传统顶板深孔爆破技术相比, 长距离钻孔爆破技术的卸压范围更大, 效果更显著。研究结论可为类似条件矿井在生产期间, 从源头对高层位、难卸压的厚硬顶板进行降载卸压防治冲击地压提供参考。Abstract: 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.