微震监测在复合坚硬砂岩体顶板控制策略优化中的应用

Application of microseismic monitoring in the optimization of control strategy for roofs composed of composite hard sandstone masses

  • 摘要:
    目的 随着我国煤炭开采深度不断增加,上覆厚层坚硬岩层运动对矿压的影响愈加复杂,而鄂尔多斯矿井多数工作面上覆岩层赋存复合坚硬砂岩体,该类型关键层特点是厚、硬、近,这导致工作面矿震与动力显现风险并存。
    方法 以鄂尔多斯地区某矿11-3106工作面为工程背景,基于微震聚集特征演化特征,采用理论分析和数值模拟的方法,对复合坚硬砂岩体顶板破断裂隙发育进行了研究,探讨了复合坚硬砂岩体顶板控制措施。
    结果和结论 研究结果表明:(1)随着工作面的推采,上覆复合坚硬砂岩体在微震显著聚集区域发生破断,并可基于微震聚集特征演化规律来判识复合坚硬砂岩体的断裂位置,该工作面微震聚集高密度区呈现“高频率−高能量”的特征,并出现区域峰值大能量事件;(2) 11-3106工作面在推采至一次见方和二次见方附近,复合坚硬砂岩体呈现2-3个小周期和1个大周期的破断特征,微震聚集在工作面走向方向动态变化;(3)基于微震聚集演化特征,优化了深孔预裂爆破的破断步距,回风巷微震聚集程度显著减少,采动影响范围缩小,效果显著。根据工作面微震聚集特征演化的复合坚硬砂岩体动态迁移现象,对复合坚硬砂岩体顶板控制措施进行优化,对鄂尔多斯矿区相似覆岩结构的工作面的顶板防治具有参考意义。

     

    Abstract: With a gradual increase in the coal mining depth in China, the movement of overlying thick and hard rock layers exerts increasingly complex impacts on the mine pressure. In the Ordos area, the overburden of the mining face of most mines hosts composite hard sandstone masses, serving as key layers characterized by considerable thicknesses, high hardness, and close proximity. As a result, the risks of mine earthquakes and dynamic manifestation co-exist in the mining face. With the roof of mining face11-3106 in a coal mine within the Ordos mining area as the engineering background, this study investigated roofs composed of composite hard sandstone masses. Based on the evolution of microseismic accumulation characteristics and using methods like theoretical analysis and numerical simulation, this study investigated the breaking-induced fracture development in the roofs and explored the control measures for the roofs. The results indicate that as the mining face advanced, the overlying composite hard sandstone masses broke in the zone with significant microseismic accumulation. The breaking positions can be identified based on the evolutionary patterns of microseismic accumulation characteristics. The high-density microseismic accumulation zone in the mining face manifested high microseismic frequency and energy, accompanied by regional peak high-energy events. As mining face 11-3106 advanced to the first and second square states (i.e., the first advancing distance of the mining face equals its length, and the second advancing distance of the mining face equals twice its length), the breaking characteristics of the composite hard sandstone masses exhibited two to three small cycles and a large cycle, with dynamic microseismic accumulation occurring along the strike of the mining face. The breaking span for deep-hole pre-splitting blasting was optimized based on the evolutionary characteristics of microseismic accumulation, significantly reducing microseismic accumulation in the air-return roadway and the mining influence range. The control measures for the roof composed of composite hard sandstone masses were optimized based on the dynamic migration of composite hard sandstone masses derived using the microseismic accumulation in the mining face. This study can serve as a reference for controlling the mining face roofs with similar overburden structures in the Ordos mining area.

     

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