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裂隙演化视角下厚硬岩层破断主导超大采高采场覆岩垮落运移机制

Influence mechanism of thick hard strata breakage on overburden collapse and movement in ultra-large mining height faces

  • 摘要: 针对特厚煤层10m超大采高工作面中厚硬岩层破断规律与覆岩垮落运移机理认识不足的问题,以曹家滩122104工作面为背景,综合采用相似模拟试验、图像处理与统计分析以及现场监测方法,研究厚硬岩层破断对覆岩垮落运移过程的主导作用,并通过现场实测数据验证模型结论的工程适用性与一致性。结果表明:(1)提出了基于多时序覆岩图像的裂隙自动提取与多指标定量方法,实现了裂隙发育高度、覆盖面积、总长度等参数的高效量化。结果表明,裂隙参数随工作面推进呈现显著的“阶梯式”跃升特征,各突变点与厚硬岩层(Ⅰ、Ⅱ、Ⅲ)的破断时序严格对应,从裂隙演化角度定量揭示了厚硬岩层破断对覆岩运移的主控作用。(2)阐明了厚硬岩层“悬臂梁-协同垮落”的破断机制:破断前其形成大跨度悬臂梁结构,限制覆岩垮落;悬臂梁达到极限时发生突发破断,触发覆岩大范围协同垮落,呈现典型结构性破坏特征。(3)现场分层沉降、矿压与微震监测结果与模型实验形成了有效互证:分层沉降曲线揭示的岩层协同运移模式与模型中的裂隙“阶梯式”扩展规律高度一致;矿压监测显示厚硬岩层Ⅱ、Ⅲ破断直接诱发强烈周期来压;微震监测进一步证实,厚硬岩层的周期性破断是覆岩能量集中释放的主要来源,从空间演化与能量释放两方面共同验证了厚硬岩层破断主导覆岩运移机制的现场适用性。本研究从裂隙演化视角系统阐明了厚硬岩层破断主导超大采高覆岩垮落运移的机理,为10m超大采高工作面覆岩运动理论完善与顶板灾害防控提供了量化理论依据。

     

    Abstract: To address the inadequate understanding of the fracturing behavior of thick-hard strata and the collapse-movement mechanism of overlying strata in 10 m ultra-large mining height faces of extra-thick coal seams, this study takes Panel 122104 of Caojiatan Coal Mine as the engineering background. A combined approach involving physical modeling simulation, image processing with statistical analysis, and field monitoring was adopted to investigate the dominant role of thick-hard strata breakage in the overburden collapse and movement process. The engineering applicability and consistency of the model results were verified with field measurements. The findings are as follows: (1) An automatic fracture extraction and multi-index quantification method based on multi-temporal overburden images was proposed, enabling efficient quantification of parameters such as fracture development height, coverage area, and total length. The results show that the fracture parameters exhibit a pronounced “step-like” jump evolution with face advance, where each abrupt change strictly corresponds to the breakage sequence of specific thick-hard strata (I, II, III). This quantitatively reveals, from the perspective of fracture evolution, the controlling effect of thick-hard strata breakage on overburden movement. (2) The “cantilever beam-coordinated collapse” breakage mechanism of thick-hard strata is clarified. Before breakage, thick-hard strata form a large-span cantilever beam structure that constrains overburden collapse; when the cantilever reaches its limit, sudden breakage occurs, triggering large-scale coordinated collapse of the overburden, demonstrating typical structural failure characteristics. (3) Field monitoring data, including layered subsidence, ground pressure, and microseismicity, provide effective mutual validation with the model experiments. The coordinated movement mode of strata revealed by the layered subsidence curves aligns well with the “step-like” propagation pattern of fractures observed in the model; ground pressure monitoring indicates that the breakage of thick-hard strata II and III directly induces intense periodic weighting; microseismic monitoring further confirms that the periodic breakage of thick-hard strata constitutes the main source of concentrated energy release in the overburden. These results jointly verify, in terms of spatial evolution and energy release, the field applicability of the mechanism by which thick-hard strata breakage dominates overburden movement. From the perspective of fracture evolution, this study systematically elucidates the mechanism of thick-hard strata breakage-dominated overburden collapse and movement under ultra-large mining height conditions, providing a quantitative theoretical basis for improving overburden movement theory and preventing roof disasters in 10 m ultra-large mining height faces.

     

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