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坚硬顶板型冲击地压发生机理及监测预警研究

Study on occurrence mechanism and monitoring and early warning of rock burst caused by hard roof

  • 摘要: 针对坚硬顶板条件下冲击地压发生频率高、强度大、破坏范围广等问题,以华丰煤矿1411工作面为工程背景,采用理论分析研究了坚硬顶板型冲击地压发生机理,分析了坚硬顶板型工作面的声发射及应力前兆信息特点,最后进行了现场实践。研究结果表明:坚硬顶板型冲击地压以能量及应力判据为主,冲击地压前兆信息主要有2个特点,即能量增大和应力突变;坚硬顶板悬空长度大,导致煤体内部集中应力持续升高,若积聚的大量弹性能不能有效安全释放,可能会导致冲击地压的发生;采用声发射和应力监测手段可及时得到坚硬顶板工作面回采过程中煤体应力及能量动态发展情况,从而对冲击危险进行预警。结合现场条件,设计采用大直径钻孔和深孔断顶爆破进行卸压解危,卸压前后最大钻粉量由4 kg/m降为3 kg/m、应力集中系数由2.03降低为1.72,且支承压力峰值向深部转移,煤体应力集中得到明显释放,卸压效果较好。

     

    Abstract: According to the high frequent occurrence, high strength, wide destroy scope and other problems occurred by the mine pressure bump under the condition of the hard roof, based on No. 1411 coal mining face in Huafeng Mine as an engineering background, the theoretical analysis was firstly applied to study the occurrence mechanism of the mine hard roof type pressure bump and then to analyze the acoustic emission and stress precursory information features of the hard rood type coal mining face. Finally the site practices were conducted. The study results showed that the mine hard roof type pressure bump was mainly based on the energy and stress criterion, the precursory information of the mine pressure bump mainly would have two features and they were the energy increased and stress sudden changed. A long free span of the hard roof would cause the concentrated stress continuously increased internally in the coal mass. Once the accumulated great elastic energy could not be effectively and softly released, a mine pressure bump would be possibly occurred. The acoustic emission and the stress monitoring means could be applied to timely obtain the coal stress and energy dynamic development conditions during the mining process of the hard roof type coal mining face. Thus the early warning could be conducted on the mine pressure bump danger. In combination with the site conditions, a large diameter borehole and deep borehole roof cutting blasting was designed and applied to the pressure released and the danger solved. Before and after the pressure released, the maximum drilling cuttings were reduced from 4 kg/m to 3 kg/m, the stress concentration parameters would be reduced from 2.03 to 1.72, the support pressure peak could be migrated to the deep section, the stress concentration of the coal would be obviously released and the pressure released effect would be good.

     

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