深部煤层开采诱发断层卸载滑移的围压效应研究

Confining pressure effect of fault unloading and slippage induced by deep coal seam mining

  • 摘要: 随着我国煤炭资源逐步转向深部开采,地质构造诱发的动力灾害问题愈发突出,断层卸载滑移作为采动应力扰动下典型的失稳形式,严重威胁矿井安全生产。【目的及方法】以甘肃某矿工作面过断层开采期间引发的一系列大能量震动事件为背景,采用双轴卸载滑移试验的方法揭示了深部采掘扰动诱发断层卸载滑移过程及其作用机制,并提出深部断层滑移的差异化防控策略。【结果】研究结果表明,断层滑移可分为应力积累、临界滑移和失稳滑移三个阶段,不同阶段滑移特征差异显著。断层滑移主要由断层面上正剪应力变化导致,其中剪应力控制着断层滑移,一旦断层面上的剪应力超过断层的最大剪切强度,断层便会发生滑移,而正应力主要影响断层的稳定性,高围压会增加断层的稳定性,一旦高围压下断层发生滑移便会产生更加显著的动力灾害。【结论】本研究可为深部煤矿开采的断层稳定性评价和灾害防治提供指导,对降低煤矿深部灾害风险具有借鉴意义。

     

    Abstract: With the continuous advancement of deep coal resource extraction in China, the issue of dynamic disasters induced by geological structures has become increasingly prominent. Among them, fault unloading slip, as a typical instability form under mining-induced stress disturbances, poses a serious threat to the safe production of mines. This study takes a series of high-energy seismic events triggered during the mining of a working face crossing a fault in a mine in Gansu Province as the background. By employing a biaxial unloading slip test method, the process and mechanism of fault unloading slip induced by deep mining disturbances were revealed, and differentiated prevention and control strategies for deep fault slips were proposed. The research results show that fault slip can be divided into three stages: stress accumulation stage, critical slip stage, and instability slip stage, with distinct slip characteristics in each stage. Fault slip is primarily caused by changes in normal shear stress on the fault plane, where shear stress governs the fault slip. Once the shear stress on the fault plane exceeds the maximum shear strength of the fault, slip will occur. Normal stress mainly affects the stability of the fault, with high confining pressure increasing fault stability. However, once slip occurs under high confining pressure, it can lead to more significant dynamic disasters. This study provides guidance for fault stability evaluation and disaster prevention in deep coal mining.

     

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