强冲击特厚煤层见方复合构造区域降载防冲技术研究

Research on load reduction and rockburst prevention technology in areas with square composite structures of extra-thick coal seams under strong impact

  • 摘要: 为揭示强冲击特厚煤层工作面回采至特殊区域的冲击危险性,提升回采期间防冲安全性,以胡家河煤矿401106工作面见方复合构造区域为工程背景,综合采用理论分析、现场实测等方法,研究了见方复合构造区域微震时空演化规律,阐释了煤岩体诱冲机理:见方复合构造区域载荷集中程度较高,微震事件频次与能量出现跃升,煤岩体裂隙破裂程度较发育,微震事件活跃程度相对剧烈,微震事件平均最大能量与每米释放能量相比常规回采区域分别升高了20.1%,26.3%,且近似呈“抛物线”分布;煤岩体在见方效应、构造作用、坚硬覆岩及相邻采空区等因素叠加影响下,冲击危险性升高。根据“分源、分类防治”思想,提出了“区域+局部”的降载防冲技术:针对孕育动静载源的坚硬覆岩,采用井下长孔区域压裂和顶板预裂爆破技术协同防控;针对积聚静载源的见方复合构造区域的煤体,采用帮部、底板松动爆破技术,降低了周期来压步距和动载系数,提升了围岩整体稳定性和回采期间的安全性。

     

    Abstract: To reveal the impact risk when mining advances into special areas of strong-impact extra-thick coal seams and to enhance rockburst prevention safety during the mining process, the square composite structure area of the 401106 working face at Hujiahe Mine was taken as the engineering background. Through a combination of theoretical analysis and field measurements, the spatiotemporal evolution characteristics of microseismic events in the square composite structure area were investigated, and the mechanism of rockburst induction was explained. It was found that the load concentration in the square composite structure area was relatively high, with a significant increase in both the frequency and energy of microseismic events. Coal-rock fractures were more developed, and microseismic activities were more intense compared to conventional areas. The average maximum energy and energy released per meter of microseismic events increased by 20.1% and 26.3%, respectively, and exhibited a parabolic distribution. Under the combined effects of the square structure effect, tectonic forces, hard overlying strata, and adjacent goafs, the impact risk of the coal-rock mass increased. Based on the principle of "source separation and classified prevention", a "regional + local" load reduction and rockburst prevention technology was proposed. Specifically, for hard overlying strata that generated dynamic and static load sources, a coordinated prevention and control approach using underground long-hole regional hydraulic fracturing and roof pre-split blasting technologies was applied. For the coal body in the square composite structure area, which accumulated static load sources, side and floor destress blasting techniques were used. These measures reduced the periodic weighting step and dynamic load factor, improved the overall stability of the surrounding rock, and enhanced safety during mining operations.

     

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