典型深厚表土煤层冲击地压模式研究

Rock burst model of typical coal seam under thick alluvium

  • 摘要: 煤矿冲击地压发生过程可描述为外部力源驱动围岩结构失稳或系统平衡状态突变。冲击地压发生过程中,应力起着重要作用。 根据主控性应力来源或类型可得到我国煤矿冲击地压的区域性特点。其中,深厚表土地层控制型冲击地压属于巨野矿区特有的冲击地压类型,其显现特征与地层结构具有密切的关联性。 针对此类冲击地压,通过案例与现场监测数据分析,探讨了典型深厚表土煤层冲击地压特征,结合煤层应力演化分析,表征了深厚表土煤层瞬时冲击和延时冲击过程,最后通过相似材料模拟试验揭示了煤层应力演化与覆岩运动、地层变形之间的关系,并对典型深厚表土煤层冲击地压模式进行了验证。 研究表明:覆岩整体失稳促使煤层应力快速达到冲击地压临界应力,发生大能量冲击地压,表土层持续变形和移动促使煤层应力缓慢达到冲击地压临界应力,再次发生冲击地压;离层发育高度与回采距离有关,但具有明显的“平台效应”,煤层应力演化与离层发育有关,但相对于回采距离具有明显的滞后性;瞬时冲击地压加载机理为“覆岩结构运动→煤层应力演化→冲击地压”,延时冲击地压加载机理为“地层变形→煤层应力增长→冲击地压”;最后,提出了深厚表土煤层冲击地压监测对策。

     

    Abstract: The process of rock burst can be described as the instability of surrounding rock structure driven by external force sources or the mutation of system equilibrium state under stress disturbance. The stress plays an important role in the process of rock burst. The regional feature of rock burst in Chinese collieries can be obtained based on the origin or type of main controlling stress. The rock burst controlled by the thick overburden is a characteristic of Juye coal mining area. The characteristics of rock burst behavior are associated with the stratum structure. The characteristics of rock burst in the typical coal seam under thick alluvium are investigated by means of case studies and in-situ monitoring da- ta analysis. Combined with the analysis of coal seam stress evolution,the process of instantaneous burst and delay burst in the coal seam under thick alluvium has been characterized. Finally,the relationship between coal seam stress evolu- tion and overlying strata movement and ground deformation is revealed by similar material simulation test,and the rock burst model of typical coal seam under thick alluvium is verified. The results show that the whole overlaying rock failure impels coal seam stress to reach the critical stress of rock burst rapidly,while ground deformation and movement result in slow increase of coal seam stress and rock burst when the stress reach the critical stress of rock burst. The de- velopment height of overlying separation is related to face advancing distance,and has an obvious platform effect. The coal seam stress evolution is related to overlying separation development,and has an obvious stagnation relative to face advancing distance. The instantaneous burst process is described as “overlying strata structure moving→coal stress e- volving→rock burst”,while the delay burst process is “ground deforming→coal stress growing→rock burst”. Monito- ring technology of rock burst in coal seam under thick alluvium is put forward in the end.

     

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