Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining,Energy Science & Engineering

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Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining
Energy Science & Engineering ( IF 3.5 ) Pub Date : 2020-04-01 , DOI: 10.1002/ese3.659
Chao Pan _{1,

2} , Binwei Xia _{1,

2} , Bin Yu ₃ , Peng Yu _{1,

2} , Yafei Luo _{1,

2} , Yugang Gao _{1,

2}

Affiliation

Traditional methods of controlling hard roofs have a limited scope of action and cannot effectively release the strong ground pressure behavior (SGPB) induced by high‐position hard roofs (HHRs) in extra‐thick coal seam mining (ETCSM). Thus, an innovative control technology of fracturing HHRs by vertical‐well stratified fracturing (VWSF) has been proposed. However, the key parameters of VWSF, namely fracturing horizon and fracturing thickness of HHRs, which have a significant influence on stope stability, remain uncertain. In this study, a mechanical model of the “coal wall–hydraulic support–gangue” support system is established by considering the effective loading acting on HHRs, through which modified expressions for the periodic breaking span and impact kinetic energy of the stope are deduced. Based on the self‐bearing of bulking rocks, the stability principle of the surrounding rock, and energy dissipation theories, the criteria for determining the fracturing horizon and thickness of the HHR are obtained. Next, a numerical model of ETCSM, which accounts for the supporting effect of gangue, is constructed in FLAC3D. The support load and energy released by stratum breakage are determined through modeling under various hard roof parameters, thus verifying the correctness of the determination criteria. The results show that the energy released by a hard roof, average support load, and critical support load are positively correlated with thickness, and first increase before declining with respect to an increase in the fracturing horizon. The key parameters for a real coal mine are obtained by theoretical calculations and numerical simulations. A field application demonstrates that the support load and advance roadway deformation can be decreased using the proposed parameterization. This provides theoretical support for determining the key parameters of HHRs for VWSF and facilitates the widespread application of VWSF technology in HHR control.

中文翻译：

确定超厚煤层开采中垂直井分层压裂释放强地压行为的高位硬顶关键参数

传统的硬顶控制方法作用范围有限，无法有效释放特厚煤层开采（ETCSM）中高位硬顶（HHR）引起的强地压力行为（SGPB）。因此，提出了一种通过垂直井分层压裂（VWSF）压裂HHRs的创新控制技术。但是，VWSF的关键参数，即HHRs的压裂水平和压裂厚度，对采场稳定性具有重大影响，仍不确定。在这项研究中，通过考虑作用于HHR的有效载荷，建立了“煤壁-水力支撑-脉石”支撑系统的力学模型，由此推导了采场的周期性破坏跨度和冲击动能的修正表达式。根据膨胀岩石的自承，得到了围岩的稳定原理，能量耗散理论，确定HHR压裂层位和厚度的判据。接下来，在FLAC3D中构造了一个ETCSM数值模型，该模型考虑了脉石的支持作用。通过在各种硬顶参数下进行建模确定由地层破裂释放的支撑载荷和能量，从而验证了确定标准的正确性。结果表明，坚硬顶板释放的能量，平均支撑载荷和临界支撑载荷与厚度呈正相关，并且相对于压裂层数的增加，其先增加后减小。通过理论计算和数值模拟获得了真实煤矿的关键参数。现场应用表明，使用建议的参数化可以减少支撑载荷和前进巷道变形。这为确定VWSF的HHR的关键参数提供了理论支持，并促进了VWSF技术在HHR控制中的广泛应用。

更新日期：2020-04-01

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