正、逆断层上盘开采冲击地压危险性分析

Analysis of rock burst risk of mining in hanging wall of normal and reverse faults

  • 摘要: 现有针对不同条件下断层冲击地压危险性的研究大部分围绕下盘开采或单一断层形式展开,而对于不同断层上盘开采冲击地压危险性的对比研究较少涉及。针对上述问题,以河南义马耿村煤矿12220工作面为研究背景,借助理论分析、数值模拟及现场监测等方法,对正、逆断层上盘开采时冲击地压危险性进行了分析。建立了正、逆断层上盘开采的力学模型,通过对断层岩块的受力分析,得出了断层上下剪滑的力学条件,理论分析结果表明:正、逆断层上盘开采时断层是否发生剪滑与断层倾角、断层内摩擦角及岩块受到的断层面作用力等因素密切相关,且工作面越靠近断层,发生剪滑的危险性越大。开展了正、逆断层上盘开采过程的数值模拟研究,对断层面法向应力、剪切应力及滑移量变化进行了分析,结果表明:在工作面开采过程中,当工作面距断层距离小于40 m后发生剪滑及冲击地压的危险性逐渐增加,距断层10 m时危险性最大,最易发生剪滑的位置为断层面的煤层顶板和煤层处,煤层底板受开采影响程度明显小于顶板;断层类型对冲击地压危险性有一定的影响,逆断层开采时的冲击地压危险性高于正断层。对12220工作面的冲击地压危险性进行了微震监测,结果表明:当工作面距断层小于20 m时,微震事件频繁,冲击地压危险性较大,与数值模拟结果一致,验证了数值模拟分析的合理性。

     

    Abstract: The existing research on the rock burst risk of faults under different conditions is mostly carried out around the footwall mining or single fault form. The comparative research on the rock burst risk of hanging wall mining of different faults is seldom involved. In order to solve the above problems, the 12220 working face of Gengcun Coal Mine in Yima, Henan is taken as the research background. The rock burst risk of mining in hanging wall of normal and reverse faults is analyzed by means of theoretical analysis, numerical simulation and field monitoring. The mechanical model of mining in the hanging wall of normal and reverse faults is established. The mechanical condition of shear slip on the fault is obtained by analyzing the stress of fault rock. The results of the theoretical analysis show that the occurrence of shear slip is closely related to such factors as fault dip angle, internal friction angle of fault and fault surface force on rock block during hanging wall mining of normal and reverse faults. The closer the working face is to the fault, the greater the risk of shear slip. The numerical simulation of the mining process in the hanging wall of normal and reverse faults is carried out, and the normal stress, shear stress and slippage of the fault plane are analyzed. The results show that in the mining process of the working face, when the distance between the working face and the fault is less than 40 m, the risk of shear slip and rock burst increases gradually. When the distance from the fault is 10 m, the risk is the greatest. The most likely position for shear slip is the coal seam roof and coal seam of the fault plane. The influence degree of the coal seam floor is obviously less than that of the roof. The type of fault has a certain impact on the rock burst risk. The rock burst risk of reverse fault mining is higher than that of normal fault. Microseismic monitoring of rock burst risk is carried out on the 12220 working face. The results show that when the working face is less than 20 m from the fault, the microseismic events are frequent and the rock burst risk is high. The results are consistent with the numerical simulation results, which verifies the rationality of the numerical simulation analysis.

     

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