负压影响下不同应力分区煤样瓦斯渗流特性及应用研究

    Research on Gas Seepage Characteristics and Application of Coal Samples in Different Stress Zones under Negative Pressure Influence

    • 摘要: 为揭示抽采负压与采动应力分区对煤体瓦斯渗流特性的耦合控制机制,以九里山矿1607工作面为工程背景,采用物理模拟实验与现场跟踪考察相结合的方法,系统研究了原岩应力区、应力集中区及卸压区煤样在8~30 kPa负压范围内的渗透率演化规律。结果表明:①负压对渗透率的影响呈显著分区特征:在原岩应力区与应力集中区,渗透率随负压增加呈“先升后降”趋势,峰值渗透率对应的临界负压约为25 kPa,归因于有效应力增加与基质收缩效应的竞争关系;在卸压区,渗透率随负压增加持续增大,表明充分发育的裂隙系统对负压驱动力具有更强的敏感性。②现场抽采效果验证了实验室规律,但最佳经济与安全负压为15 kPa,在此负压下抽采纯量达到最大值(0.24 m3/min),更高负压(30 kPa)会因漏风加剧及近孔裂隙闭合导致抽采效率下降。研究确定了本工作面合理抽采负压为15 kPa,成果可为类似条件矿井的抽采参数优化提供理论依据与技术参考。

       

      Abstract: To reveal the coupled control mechanism of extraction negative pressure and mining-induced stress zoning on coal gas permeability, taking the 1607 working face of Jiulishan Mine as the engineering background, a combination of physical simulation experiments and field tests was conducted. The permeability evolution of coal samples from the in-situ stress zone, stress concentration zone, and pressure-relief zone under negative pressures ranging from 8 to 30 kPa was systematically investigated. Results show: (1) Negative pressure has a significant zoning effect on permeability. In the in-situ stress zone and stress concentration zone, permeability first increases and then decreases with rising negative pressure, peaking at approximately 25 kPa, which is attributed to the competition between effective stress increase and matrix shrinkage. In the pressure-relief zone, permeability continuously increases, indicating that the well-developed fracture system is more sensitive to negative pressure driving force. (2) Field tests confirmed the laboratory results, but the optimal negative pressure for safety and economy is 15 kPa, at which the pure gas drainage rate reaches a maximum of 0.24 m3/min. Higher negative pressure (30 kPa) reduces extraction efficiency due to intensified air leakage and near-borehole fracture closure. The reasonable negative pressure of 15 kPa is determined for this working face, providing theoretical basis and technical reference for extraction parameter optimization in mines with similar conditions.

       

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