Song Weihua, Yan Luo, Jiao Huice
College of Mining, Liaoning Technical University, Fuxin, Liaoning, China.
Sci Rep. 2025 Jul 1;15(1):20362. doi: 10.1038/s41598-025-09179-5.
In deep mining environments, normal fault structures significantly influence coal seam permeability, which plays a crucial role in coal and gas outbursts. Utilizing a true triaxial multifunctional physical simulation system, this study conducted gas seepage and hydraulic fracturing experiments on normal fault-associated coal seams at depths of - 400 m, - 600 m, and - 800 m. The research systematically investigates the gas permeability evolution in hanging wall and footwall coal seams of normal faults and proposes enhanced control measures tailored to the Guodishan normal fault. The results showed: Permeability exhibited a negative exponential relationship with confining pressure. As confining pressure increases, the permeability disparity between the hanging wall and footwall diminishes. Under true triaxial conditions, the permeability of the coal in the hanging wall of the normal fault is generally lower than that in the footwall. This difference gradually increases with burial depth, with the permeability ratio between the two sides increasing from 2.96 to 10.2 times. Moreover, the permeability reduction in the hanging wall coal is greater than that in the footwall coal. The crack initiation pressure for fracturing is higher in the hanging wall. Post-fracturing, permeability increases significantly in both walls, with the footwall demonstrating superior enhancement. However, the permeability amplification factor decreases progressively with depth. Building on the evolutionary characteristics of the Guodishan normal fault and its permeability patterns, targeted gas control strategies were developed in the Pingdingshan mining area. This work provides theoretical and practical guidance for gas extraction and outburst prevention in fault-affected coal seams.
在深部开采环境中，正断层结构对煤层渗透率有显著影响，而煤层渗透率在煤与瓦斯突出中起着关键作用。本研究利用真三轴多功能物理模拟系统，对埋深为-400m、-600m和-800m的与正断层相关的煤层进行了瓦斯渗流和水力压裂实验。系统研究了正断层上盘和下盘煤层瓦斯渗透率的演化规律，提出了针对锅底山正断层的强化控制措施。结果表明：渗透率与围压呈负指数关系。随着围压增大，上盘与下盘的渗透率差异减小。在真三轴条件下，正断层上盘煤的渗透率普遍低于下盘煤。这种差异随埋深逐渐增大，两侧渗透率比值从2.96增大到10.2倍。而且，上盘煤渗透率降低幅度大于下盘煤。上盘水力压裂的起裂压力较高。压裂后，两盘渗透率均显著增加，下盘增幅更优。然而，渗透率放大倍数随深度逐渐减小。基于锅底山正断层的演化特征及其渗透率规律，在平顶山矿区制定了针对性的瓦斯防治策略。该研究为断层影响煤层的瓦斯抽采和防突工作提供了理论和实践指导。
