基于微震−电法技术的煤层顶板采动裂隙及其富水异常监测

Monitoring of mining-induced fractures and associated water-rich anomalies in coal seam roofs using microseismic and electrical methods

  • 摘要: 微震监测、矿井音频电透视是煤矿顶板灾变监测的核心技术手段,但单一技术无法同时获取裂隙力学发育过程及其富水状态。针对该问题,提出融合微震监测和矿井音频电透视的煤层顶板采动裂隙及其富水异常监测技术,通过统一2套监测系统的空间坐标,实现微震破裂定位与三维视电阻率成像的空间耦合,经多参量联合解译,判断富水异常的力学成因及裂隙发育区含水性等信息。以文家坡煤矿4106工作面为工程研究背景开展联合监测,结果表明:微震事件垂向上距顶板越近能量占比越大,回采过程中导水断裂带发育高度未波及宜君−洛河组含水层底板,覆岩破坏存在明显周期效应,回采进尺推进至约2倍工作面倾向长度附近是顶板覆岩破裂、裂隙向上扩展的高危阶段;工作面采动应力作用下,顶板覆岩破裂区出现明显低阻富水异常区,且异常区向采空区及区段煤柱一侧延展;微震能量集中区与电法低阻异常区呈显著的空间耦合特征,裂隙发育的力学过程加剧了区域裂隙富水性增强。该技术构建了“动态监测−静态成像−联合解译”体系,为顶板水害预警和透明工作面搭建提供技术支撑。

     

    Abstract: Microseismic monitoring and the mine audio-frequency electric perspective method are key techniques for monitoring roof disasters in coal mines, but neither can simultaneously capture the mechanical evolution of fractures and their water-bearing condition. To address this problem, a method integrating microseismic monitoring and the mine audio-frequency electric perspective method was proposed to monitor mining-induced fractures and associated water-rich anomalies in coal seam roofs. By unifying the spatial coordinate systems of the two monitoring systems, spatial coupling between microseismic source locations and three-dimensional apparent-resistivity images was achieved, and multi-parameter joint interpretation was used to determine the mechanical causes of water-rich anomalies and the water-bearing characteristics of fractured zones. Joint monitoring was conducted at working face 4106 of Wenjiapo Coal Mine. The results showed that the proportion of microseismic energy increased as events occurred closer to the roof in the vertical direction. During mining, the water-conducting fracture zone did not extend to the floor of the Yijun-Luohe Formation aquifer, and overburden failure exhibited a pronounced periodic pattern. When the mining advance approached twice the dip length of the working face, this stage represented a high-risk period for roof-overburden rupture and upward fracture propagation. Under mining-induced stress, a distinct low-resistivity, water-rich anomalous zone developed in the roof-overburden fracture zone and extended toward the goaf and the side adjacent to the section coal pillar. Microseismic energy concentration zones were markedly spatially coupled with low-resistivity electrical anomaly zones, and the mechanical process of fracture development further increased the water richness of fractures in the region. The method establishes a 'dynamic monitoring–static imaging–joint interpretation' framework and provides technical support for early warning of roof water hazards and development of transparent working faces.

     

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