刘怀东,刘长友,杨培举,等. 向斜构造区特厚煤层开采覆岩结构稳定性及突水压架机理[J]. 煤炭学报,2024,49(9):3745−3758. DOI: 10.13225/j.cnki.jccs.2023.1068
引用本文: 刘怀东,刘长友,杨培举,等. 向斜构造区特厚煤层开采覆岩结构稳定性及突水压架机理[J]. 煤炭学报,2024,49(9):3745−3758. DOI: 10.13225/j.cnki.jccs.2023.1068
LIU Huaidong,LIU Changyou,YANG Peiju,et al. Structural stability of overlying rock and mechanism of water inrush and support crushing in extra-thick coal seam mining within syncline structural area[J]. Journal of China Coal Society,2024,49(9):3745−3758. DOI: 10.13225/j.cnki.jccs.2023.1068
Citation: LIU Huaidong,LIU Changyou,YANG Peiju,et al. Structural stability of overlying rock and mechanism of water inrush and support crushing in extra-thick coal seam mining within syncline structural area[J]. Journal of China Coal Society,2024,49(9):3745−3758. DOI: 10.13225/j.cnki.jccs.2023.1068

向斜构造区特厚煤层开采覆岩结构稳定性及突水压架机理

Structural stability of overlying rock and mechanism of water inrush and support crushing in extra-thick coal seam mining within syncline structural area

  • 摘要: 针对陕西省永陇矿区褶曲构造带突水压架事故频发问题,以陕西省郭家河煤矿为工程背景,采用现场调研、物理实验与理论分析的方法,确定了导致工作面突水压架的主要含水层,得出了向斜构造区煤层开采覆岩破断失稳特征,建立了考虑承压水作用的覆岩结构力学模型,推导了工作面突水压架的临界水压力,揭示了向斜构造区突水压架机理。研究表明:① 1303、1304、1308等已开采工作面在向斜轴部区域均发生过突水压架事故,宜君组岩层是导致工作面突水事故的主要含水层,煤层之上102.5 m处厚度为28.53 m的中粒砂岩为隔水关键层。隔水关键层断裂后,其上部100.51 m载荷层同步破断,导水裂隙带导通宜君组含水层。② 在向斜构造区俯采阶段,顶板覆岩具有多层亚关键层并形成多离层区。向斜轴部岩层破断角竖直发育,顶板破坏程度最高,压架风险最大。③ 顶板突水致使覆岩结构失稳是导致压架事故发生的关键。承压水对顶板岩层稳定性的影响主要表现为:增加了覆岩载荷传递的连续性,降低了组合亚关键层的承载能力;构成了组合亚关键层的附加载荷。④ 防止突水压架所需的支护阻力随承压水压力的增大而加速增加,工作面发生突水压架事故的临界承压水压力为0.98 MPa。控制导水裂隙带发育高度与降低宜君组承压水压力是保证工作面不发生压架事故的关键。

     

    Abstract: With the aim of addressing the frequent occurrence of water inrush and support crushing (WISC) accidents in the fold structure belt of the Yonglong mining area, this study is conducted against the engineering background of the Guojiahe Coal Mine. The research methods encompassing field investigation, physical experimentation, and theoretical analysis are adopted. Accordingly, the main aquifer leading to WISC in the working face is determined, obtaining the failure and instability characteristics of overlying rock during coal seam mining within the syncline structural area. A mechanical model considering the influence of confined water on the overlying rock structure is established, deducing the critical water pressure and revealing the mechanism for WISC at the working face within the syncline structural area. The study reveals that: ① The WISC accidents occur at the mining faces 1303, 1304, and 1308 within the syncline axis region. The Yijun formation serves as the principal aquifer responsible for these incidents. The key waterproofing layer composed of medium-grained sandstone with a thickness of 28.53 m is located at 102.5 m above the coal seam. Upon the rupture of the key waterproofing layer, the upper load layer with a thickness of 100.51 m fractures simultaneously, resulting in the propagation of a water-conducting fracture zone towards the Yijun aquifer. ② During the decline mining stage of the syncline structural area, a multi-layered sub-key layer is observed in the roof overburden, leading to the formation of a multi-layer separation zone. The angle of strata breakage along the syncline axis exhibits vertical development, resulting in the elevated degree of roof failure and posing a significant risk of support crushing. ③ The instability of the overlying rock structure, resulting from water inrush from the roof, constitutes a pivotal factor contributing to the occurrence of the support crushing accident. The impact of confined water on roof strata stability is manifested primarily in the following ways: it enhances the load transfer continuity in overlying strata, diminishes the bearing capacity of combined subkey strata, and constitutes an additional load for combined subkey strata. ④ The required support resistance to prevent water inrush and support crushing increases with the rise of confined water pressure, and the critical confined water pressure for a WISC in the working face is 0.98 MPa. Therefore, controlling the development height of the water diversion fracture zone and reducing the confined water pressure of the Yijun formation are crucial for preventing pressure frame accidents in the working face.

     

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