Impact hazard analysis and prevention research of square structure area in fully mechanized working face
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摘要: 目前针对综放工作面的冲击危险性分析只是从单一地质构造或见方效应因素考虑,而冲击地压矿井的开采条件一直变化,影响因素复杂多样,需要具体分析综放开采条件下地质构造与见方效应耦合区域内的冲击危险性。以胡家河煤矿401111工作面为工程背景,采用微震台网监测技术获取了见方构造区内微震事件能量及频次分布特征,研究了见方构造区的冲击危险性,得出以下结论:① 见方构造区冲击危险性高,区域内断层及褶曲分别影响煤层连续性及变形特征,致使构造应力异常。② 上覆岩层压力伴随工作面开挖逐渐向煤层转移,区域内静载荷集中程度显著,工作面推进过程见方效应致使顶板活动频繁,导致较高水平的集中动载荷。③ 见方效应与地质构造联合作用时,工作面近场煤体内集中静载荷处于最高水平,远场集中动载荷扰动最频繁,两者耦合作用下的区域冲击潜在风险极大。针对见方构造区存在的冲击危险性,从空间维度由上及下对见方构造区的3个层位采取了具体的防治措施:① 厚硬顶板断裂会产生较高水平的动载荷,对其进行预裂爆破, 降低顶板与相邻采空区的联通活动。② 工作面间煤柱及实体煤受上覆岩层的压力影响,静载荷集中程度高,实施大直径钻孔卸压,降低煤帮完整性支承压力向深处煤层转移。③ 对底板实施大直径钻孔+爆破卸压技术,阻断帮部支承压力向底板转移路径,降低巷道底鼓变形。工程实践结果表明,该防治措施卸压效果良好,见方构造区内顶板周期来压步距缩短,基本在15 m以内,工作面微震事件能量均小于104 J,无大能量事件发生,可为同类型矿井条件的冲击地压防治提供参考。Abstract: At present, the impact hazard analysis of fully mechanized working face is only carried out from a single geological structure or square effect factor. However, the mining conditions of rock burst mines are always changing, and the influencing factors are complex and diverse. Therefore, it is necessary to specifically analyze the impact hazard in the coupled area of geological structure and square effect in fully mechanized working face. Taking the 401111 working face of Hujiahe Coal Mine as the engineering background, the energy and frequency distribution characteristics of microseismic events of square structure area are obtained by microseismic network monitoring technology, and the impact hazard of square structure area is studied. The conclusions are listed as follows. ① The impact hazard is high in the square structure area, and the faults and folds in the area affect the continuity and deformation characteristics of the coal seam respectively, resulting in abnormal tectonic stress. ② The pressure of the overlying rock seam gradually transfers to the coal seam along with the excavation of the working face, and the concentration of static load in the area is significant. The square effect of the working face advancement process leads to frequent roof movement, resulting in a high level of concentrated dynamic load. ③ When the square effect and geological structure are combined, the concentrated static load in the coal body near the working face is at the highest level. The far-field concentrated dynamic load disturbance is the most frequent, and the potential hazard of regional impact under the coupling effect of the two is extremely great. In order to solve the problem of the impact hazards in the square structure area, specific prevention and control measures are taken for the three layers of the square structure area from top to bottom of the spatial dimension. ① The fracture of the thick hard roof will generate a high level of dynamic load, and pre-splitting blasting is carried out to reduce the connection between the roof and the adjacent goaf. ② The coal pillars and solid coal between the working faces are affected by the pressure of the overlying rock layer, and the static load concentration is high. It is proposed to implement large diameter drill holes to unload pressure and reduce the transfer of coal wall integrity support pressure to deep coal seams.③ It is proposed to implement large-diameter drilling + blasting pressure relief technology on the bottom plate to block the transfer path of the support pressure of the wall to the bottom plate and reduce the deformation of the bottom heave of the roadway. The results of engineering practice show that the prevention and control measures have good effect of pressure relief. The roof periodic weighting in the square structure area is shortened, which is basically below 15 m. The energy of the microseismic events at the working face is less than 104 J, and there is no large energy event. The proposed measures can provide reference for the prevention and control of rock burst in the same type of mine conditions.
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Key words:
- fully mechanized working face /
- impact hazard /
- square structure area /
- square effect /
- dynamic load /
- static load
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