近距离煤层群重复采动导水裂隙带演化规律及防治水措施研究

Evolution Patterns of Water−Guiding Fracture Zones Due to Repeated Mining in Close−Bearing Coal Bed Groups and Measures for Water Control

  • 摘要: 凉水井煤矿地处陕北侏罗纪煤田,具备典型的近距离煤层群赋存条件,重复采动效应显著。针对该矿多层重复采动、基岩隔水层缺失、含水层富水性强等复杂地质开采条件,综合采用物理相似模拟、数值模拟与现场实测相结合的方法,系统研究了近距离煤层群开采过程中覆岩导水裂隙带的动态演化规律。研究表明:重复采动条件下,导水裂隙呈现明显的“活化扩展”特征,下部煤层开采后采动应力重分布,激活上部采空区既有裂隙,促使裂隙带高度非线性快速增长;间隔岩层的完全破断是裂隙快速向上延伸的关键控制节点,突破后裂隙发育高度呈突增态势;多煤层开采之间存在稳定压实阶段,覆岩裂隙在自重压实及黏土遇水膨胀作用下表现出一定的自愈闭合能力,可恢复部分隔水性能,形成从发育活化到压实闭合的动态演化机制。基于上述演化规律,提出了分层协调开采策略,构建了“源头控制—渗流削减—风险消除”立体化顶板水害协同防控体系,有效抑制了导水裂隙带的过度发育,保护了强富水性含水层的结构完整性,实现了矿井安全高效生产,为类似地质条件下的近距离煤层群保水开采提供了理论依据与工程借鉴。

     

    Abstract: Located in the Jurassic coalfield of northern Shaanxi, Liangshuijing Coal Mine exhibits typical conditions for close−range coal seam clusters and significant repeated mining effects. Addressing complex geological conditions—including multi−layered repeated mining, the absence of basement water barriers, and strong aquifer permeability—the study employed a combination of physical similarity modeling, numerical simulations, and field measurements to systematically investigate the dynamic evolution of water−conducting fracture zones in overlying rock during close−range coal mining. Results demonstrate that under repeated mining conditions, water−conducting fractures exhibit pronounced "activation and expansion" characteristics: mining activities cause stress redistribution in lower coal seams, activating existing fractures in upper goaf areas and inducing rapid nonlinear growth of fracture zones; complete fracture failure of inter−bedding rocks serves as a critical control point for upward fracture extension, with fracture development height showing abrupt increases after breakthrough; stable compaction phases occur between mining layers, where overlying rock fractures demonstrate self−healing capacity through gravity−induced compaction and clay swelling upon water contact, partially restoring water−barrier properties, thus forming a dynamic evolution mechanism of "development → activation → compaction closure." Based on the aforementioned evolutionary principles, a layered coordinated mining strategy was proposed, establishing a three−dimensional integrated prevention and control system for roof water hazards comprising "source control – seepage reduction – risk elimination." This approach effectively curbed the excessive development of water−conducting fracture zones, preserved the integrity of highly water−rich aquifers, and ensured safe and efficient mine operations, and provides both theoretical foundations and practical references for water−preserving mining of close−coal seams under similar geological conditions.

     

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