School of Resources and Safety Engineering, China University of Mining and Technology (Beiing) School of
Mechanics and Civil Engineering, China University of Mining and Technology (Beiing)

为解决厚层坚硬石灰岩顶板煤层开采过程中悬顶面积大的问题,综合运用理论分析、数值模拟、现场实测等手段,采用深孔预裂爆破技术控制初次来压步距。研究表明:原生顶板条件下,根据关键层理论预计工作面初次来压步距为59.2 m,顶板来压非常强烈。通过数值模拟分析深孔爆破裂纹扩展特征,在开切眼实施深孔预裂爆破后,沿炮孔径向产生大量次生裂隙,破坏了K2石灰岩的完整性。根据爆破过程中炮孔周围监测点应变响应特征,确定炮孔间距为6 m。支架工作阻力在线监测系统显示初次来压步距平均值为34.3 m,动载系数为1.35。工作面初次来压步距减小24.9 m,来压强度减弱,实现了工作面初采阶段安全高效生产。

In order to solve a large suspended roof area problem occurred during the coal mining process in seam with thick and hard limestone roof, a theoretical . analysis, numerical simulation, site measurement and other means were comprehensively applied to study the deep borehole pre-fracturing blasting technology to contr ol the initial roof weighting step distance. The study showed that under the primary roof condition and according to the key stratum theory, first weighting interval of coal mining face was estimated to 59.2 m and the roof weighting was very serious.With the cracking expansion features of the deep borehole blasting analyzed with the num erical simulation, after the deep borehole pre-fracturing conducted in the open-off cut of the coal mining face, great secondary cracks occurred along the blasting boreh ole radially and the integrity of K2 limestone was destroyed.According to the strain responses features of the monitoring and measuring points around the blasting bore holes during the blasting process, the spacing between the boreholes determined was 6 m.The online monitoring and measuring system of the powered support working resistances showed that the average value of the first weighting interval was 34.3 m and the dynamic load coefficient was 1.35.The first weighting interval of the coal mi ning face was reduced by 24.9 m, the roof weighting intensity was weakened and a safety and high efficient production of the coal mining face was realized at the initial mining stage.

国家重点基础研究发展计划(973计划)资助项目(2010CB226801；2010CB226804)；国家自然科学基金资助项目(51174213)；