煤炭绿色开发地质保障体系的构建

为推进瓦斯抽采钻孔精准智能化发展水平，基于分布式光纤监测和布里渊光学时域分析技术(BOTDA)，以山西某矿为工程背景，开展了不同粒径配比下的钻孔堵孔模拟实验；构建了试验矿井堵孔率计算数学模型，揭示了钻孔变形塌孔发育规律，提出了适用于试验矿井的瓦斯抽采钻孔精准监测现场实施技术工艺，并通过现场试验对技术工艺的可行性和准确性进行了验证。结果表明：(1)光纤耦合体应变、模拟煤样堆积质量与钻孔变形塌孔间具有线性关系，随质量增加应变变化趋势相近，呈“陡−缓−陡”三阶段变化。通过分段拟合构建了适用于试验矿井的钻孔堵孔率计算数学模型。(2)通过误差分析，发现随着应变增加最大绝对误差先变大后变小再变大，中期最大绝对误差为19.48 %，后期完全堵孔状态下的质量极值越接近不同配比煤样的平均质量极值误差越小。(3)基于上述数学模型解算，揭示了模拟堵孔过程中煤块首先在钻孔底部呈“凸”状堆积，随后滑向两侧，最后又在顶部聚集的塌孔演化规律，以应变值0、45.95×10⁻⁶、72.19×10⁻⁶为临界值区分塌孔前、中、后期，构建了适用于试验矿井的瓦斯抽采钻孔精准监测技术。通过现场应变监测结果分析，发现在孔周应力、扰动等因素作用下，失稳孔段孔周裂隙更易发育，塌孔程度随时间加剧。结合钻孔沿程堵孔率计算结果，对钻孔沿程变形塌孔情况进行了判断，对比钻孔窥视图可得，该精准监测技术判断结果基本符合实际观测情况。提出的以分布式光纤耦合体和BOTDA技术为基础的钻孔精准监测技术工艺可行、可靠，可为推进瓦斯抽采钻孔精准智能化发展水平提供参考。

Construction of geological guarantee system for green coal mining

This study aims to promote the precise and intelligent monitoring of gas drainage boreholes. In the engineering background of a coal mine in Shanxi Province, this study conducted simulation experiments on the plugging of gas extraction boreholes under varying particle size ratios of simulated coal samples using distributed optical fiber monitoring and the Brillouin Optical Time-Domain Analysis (BOTDA). Then, this study established a mathematical model for calculating the borehole plugging rate of the test mine, revealing the deformation and collapse patterns of gas drainage boreholes. Furthermore, this study proposed a precise in-situ monitoring technology for the gas drainage boreholes in the test mine and verified its feasibility and accuracy through field tests. Key findings are as follows: (1) There existed a linear correlation between the strain measured by fiber couplers, the mass of simulated coal samples, and the deformation and collapse of the boreholes. With an increase in the coal sample mass, the strain exhibited similar variation trends, increasing sharply, generally, and sharply in sequence. A mathematical model for calculating the borehole plugging rate was established through segmented fitting. (2) The error analysis revealed that with an increase in the strain, the maximum absolute error between the actual and theoretical borehole plugging rates manifested a trend of initial increase, followed by decrease and then increase, equaling 19.48% in the middle collapse stage. Under complete borehole plugging in the late collapse stage, the local maximum of the coal sample mass closer to the average local maximum of the mass of coal samples with different particle size ratios corresponded to a smaller error. (3) Based on calculations using the mathematical model, this study revealed the boreholes’ collapse pattern during the borehole plugging simulation. Specifically, coal blocks first accumulated in a convex shape at the bottom of a borehole, then slid toward both sides, and finally accumulated at the borehole’s top. With strain values of 0, 45.95×10⁻⁶, and 72.19×10⁻⁶ as critical values, this study determined the early, middle, and late stages of borehole collapse, developing the precise monitoring technology for the gas drainage boreholes in the test mine. As indicated by the analysis of in-situ strain monitoring results, fractures are prone to form around the boreholes in their unstable segments under the action of factors such as stress and disturbance, with borehole collapse intensifying over time. By combining the calculated plugging rates along the boreholes, this study determined the deformation and collapse along the boreholes. Comparison with the boreholes’ inside images reveals that the results obtained using the precise monitoring technology are roughly consistent with actual observations. Therefore, the precise borehole monitoring technology based on the distributed fiber optic coupler and the BOTDA is feasible and reliable, serving as a reference for advancing the precise and intelligent monitoring of gas drainage boreholes.