Yang Zhenhua, Liu Xiaoshuai, Fan Chaojun, Li Sheng, Wang Xuezeng, Liu Longkang
College of Mining, Liaoning Technical University, Fuxin 123000, China.
Liaoning Geology Engineering Vocational College, Dandong 118000, China.
ACS Omega. 2024 Jun 1;9(23):24864-24879. doi: 10.1021/acsomega.4c01684. eCollection 2024 Jun 11.
The deep highly gassy soft coal seam has the characteristics of high ground stress, high gas pressure, and low permeability. In the process of coal roadway excavation, there are problems such as frequent gas concentration exceeding the limit and easy induction of gas dynamic disasters. To investigate the pressure relief and disaster reduction efficiency of large-diameter boreholes in a deep high-gas soft coal seam, the 8002 high-gas working face of the Wuyang coal mine was taken as the engineering background to study the deformation law of large-diameter boreholes in deep high-gas soft coal seams. A coupled damage-stress-seepage model for pressure relief of large-diameter boreholes in gas-bearing coal seams was constructed based on the Hoek-Brown criterion, the correlation between the damage area and the gas pressure distribution in the gas-bearing coal seam after the pressure relief of boreholes of different apertures was analyzed, and the pressure relief efficiency of different technical parameters "three flower holes" in the roadway head was determined. The law of stress transfer, gas migration, and energy release in the coal seam after pressure relief of a large-diameter borehole under different initial gas pressures was revealed, and the power function equations of the damage range and borehole diameter, maximum stress at the roadway head, and driving distance after pressure relief of a gas-bearing coal seam were determined. Results showed that under the confining pressure of the 8002 working face roadway in the Wuyang coal mine, the pressure relief effect of 250 mm aperture is better, the drilling plastic zone is "butterfly" or "X″-type distribution, and the plastic zone range is positively correlated with the aperture size. Under the arrangement of "three flower holes", the plastic zone is larger and the pressure relief effect is better when the hole spacing is 1.4 m. With the increase of initial gas pressure, the vertical stress above the borehole increases and the pressure relief efficiency decreases. According to the vertical stress distribution within 200 h of borehole pressure relief, the pressure relief process is divided into a coal damage and failure stage, stress balance stage, and hole collapse stability stage. The research results provide a theoretical basis for the prevention and control of coal rock gas dynamic disasters by large-diameter drilling in a deep high-gas soft coal seam.
深部高瓦斯松软煤层具有高地应力、高瓦斯压力和低渗透率的特点。在煤巷掘进过程中，存在瓦斯浓度频繁超限、易诱发瓦斯动力灾害等问题。为研究大直径钻孔在深部高瓦斯松软煤层中的卸压减灾效果，以五阳煤矿8002高瓦斯工作面为工程背景，研究深部高瓦斯松软煤层大直径钻孔的变形规律。基于Hoek-Brown准则建立了含瓦斯煤层大直径钻孔卸压的损伤-应力-渗流耦合模型，分析了不同孔径钻孔卸压后含瓦斯煤层损伤区域与瓦斯压力分布的相关性，确定了巷道掘进头不同技术参数“三花孔”的卸压效果。揭示了不同初始瓦斯压力下大直径钻孔卸压后煤层中的应力转移、瓦斯运移和能量释放规律，确定了含瓦斯煤层损伤范围与钻孔直径、巷道掘进头最大应力、卸压后推进距离的幂函数方程。结果表明，在五阳煤矿8002工作面巷道围压作用下，孔径250 mm的卸压效果较好，钻孔塑性区呈“蝴蝶”或“X”型分布，塑性区范围与孔径大小呈正相关。在“三花孔”布置方式下，孔间距为1.4 m时塑性区较大，卸压效果较好。随着初始瓦斯压力的增加，钻孔上方垂直应力增大，卸压效率降低。根据钻孔卸压200 h内的垂直应力分布，将卸压过程分为煤体损伤破坏阶段、应力平衡阶段和钻孔垮塌稳定阶段。研究成果为深部高瓦斯松软煤层大直径钻孔防治煤岩瓦斯动力灾害提供了理论依据。
