“呼吸”现象下浅埋极近距离煤层采空区群漏风规律及防控研究

Air leakage patterns and control of goaf groups in shallow-buried extremely close coal seams under "breathing" phenomenon

  • 摘要: 浅埋极近距离煤层采空区群漏风网络极为复杂,外界气压扰动引发的“呼吸”现象为采空区煤自燃防治带来极大挑战。目前针对该漏风网络的内部动态连通规律的认识尚不充分,当采空区与地表无贯通裂隙时,大气参数变化与采空区“呼吸”现象及漏风强度的关联性仍有待揭示。针对上述问题,以唐山沟煤矿83103工作面为工程背景,综合运用地表裂隙观测、能位测定与示踪技术,对极近距离煤层采空区群动态漏风规律进行研究,揭示了采空区与地表无贯通裂隙情况下,不同天气下大气参数的动态变化对“呼吸”现象的驱动机制及对采空区群漏风强度的影响,并提出了针对浅埋极近距离煤层的采空区群协同防控措施。研究结果表明:地表裂隙与83103工作面采空区未形成有效贯通;83103工作面采空区与邻近及上覆采空区群形成了“水平对流−垂直下泄”的立体漏风网络;“呼吸”现象受压差驱动,地表温度及地表大气压分别与压差呈正、负相关,在持续正压差的作用下,邻近及上覆采空区有害气体大量涌出。基于上述研究结果,提出了以均压调控、裂隙封堵、注浆加固及抽采置换为主的协同漏风防控措施;治理后的83103工作面回风隅角的CO体积分数下降了48.6%,O2体积分数恢复至20%左右,有效控制了有害气体下泄问题。

     

    Abstract: The air leakage network of goaf groups in shallow-buried extremely close coal seams is highly complex, and the "breathing" phenomenon induced by external atmospheric pressure disturbances poses great challenges to the prevention and control of coal spontaneous combustion in goafs. At present, the internal dynamic connectivity of this leakage network is not fully understood. When there are no through-going fractures between the goaf and the surface, the relationship between atmospheric parameter variations, the "breathing" phenomenon, and air leakage intensity remains unclear. To address this issue, taking the working face 83103 of Tangshangou Coal Mine as the engineering background, surface fracture observation, energy potential measurement, and tracer techniques were comprehensively used to investigate the dynamic air leakage patterns of the goaf groups in extremely close coal seams. The driving mechanism of the "breathing" phenomenon induced by dynamic changes of atmospheric parameters under different weather conditions and its influence on air leakage intensity of the goaf groups were revealed in the absence of through-going fractures between the goaf and the surface. Coordinated prevention and control measures for goaf groups in shallow-buried extremely close coal seams were proposed. The results showed that surface fractures did not form effective connections with the goaf of the working face 83103. A three-dimensional air leakage network of "horizontal convection–vertical downward leakage" was formed among the goaf of the working face 83103 and the adjacent and overlying goaf groups. The "breathing" phenomenon was driven by the pressure difference. Surface temperature and surface atmospheric pressure were positively and negatively correlated with the pressure difference, respectively. Under sustained positive pressure difference, harmful gases from adjacent and overlying goaf groups were released in large quantities. Based on these findings, coordinated control measures focusing on pressure equalization regulation, fracture sealing, grouting reinforcement, and extraction–replacement were proposed. After treatment, the volume fraction of CO in the return air corner of the 83103 working face decreased by 48.6%, and the volume fraction of O2 recovered to about 20%, effectively controlling the downward leakage of harmful gases.

     

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