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大范围采动影响下特大断层构造区微震活动规律及调控方法

Microseismic activity law and control methods in mega-fault structure area under the influence of extensive mining

  • 摘要: 为大范围采动影响下特大断层构造区冲击地压防控提供参考,以济宁二号煤矿落差达百米级八里铺断层构造区为工程背景,研究了全矿井及八里铺断层上下盘采区的微震活动规律,基于微震累积能量分析了八里铺断层活动性,探讨了特大断层构造区微震活动调控方法,同时进行了工程实践。研究结果表明:大范围采动影响下,济宁二号煤矿微震事件以均匀分布于工作面及巷道区域的低能量量级事件为主,主要来源于顶板岩层运动;沿八里铺断层面没有产生集中、连续、大范围分布的微震事件,但微震事件随着工作面与断层距离减小而增加,即开采对断层具有明显扰动效应,但目前采动强度不足以造成八里铺断层活动;断层构造区微震最高累积能量整体呈稳定趋势,但集中位置随采掘状态改变而不断变化,尤其受工作面回采速度及强度影响较为明显;留设大宽度保护煤柱是调控特大断层构造区微震活动的有效方法,同时辅以顶板预裂和煤体卸压,能够实现特大断层构造区域煤层安全开采。基于不同类型断层在回采过程中的冲击地压防控思路,针对八里铺断层构造区10303工作面进行了工程实践,发现回采过程中工作面微震活动强度明显减弱,单日微震总能量降低,而单日微震频次增加,即能量释放呈多次低能释放的特征。

     

    Abstract: To provide a reference for rock burst prevention and control in mega-fault structure area under the influence of extensive mining, the Balipu Fault (i.e. the drop reaches up to 100 meters) in Jining No. 2 Coal Mine has been selected as the engineering background for the study. The microseismic behavior of the entire mine as well as the footwall and hanging wall of the Balipu Fault was studied, and the fault activity was analyzed based on the accumulated microseismic energy. Additionally, the control methods of microseismic activities in mega-fault structure area were explored, and then the engineering application was carried out. Results show that: Under the influence of extensive mining, low-energy-level microseismic events were uniformly distributed in the mining face and roadway areas in the Jining No. 2 Coal Mine, which principally come from regular roof strata movement. There were no concentrated, continuous, and widely distributed microseismic events observed along the Balipu Fault plane. The microseismic events increased with the decrease of distance between the mining face and fault plane. It means that the mining can disturb the fault plane, but the current mining intensity was not enough to induce the fault activation. The highest cumulative energy of microseismic in the fault structure area exhibited an overall stable trend, but the concentrating position continuously varied as changing the mining conditions, particularly influenced by the mining speed and intensity. The effective solution is to leave a wide protective coal pillar for mitigating microseismic activity and achieving safe mining in mega-fault structure area, accompanied with reasonable roof pre-fracturing and coal pressure relief. Engineering practice was carried out in the 103lower03 mining face of the Balipu Fault area based on the rock burst control strategy of different fault types. It was observed that the intensity of microseismic activity was noticeably weakened during the mining process. The total microseismic energy of one day decreased, while the microseismic frequency increased, indicating that a high frequency-low intensity of energy release.

     

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