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某金属矿山近地表历史采空区综合探查与稳定性分析

Integrated investigation and stability analysis of near-surface historical goafs in metal mine

  • 摘要: 针对长期地下开采形成的历史采空区位置不明确、空间关系复杂及稳定状态难以准确判定等问题,以某金属矿山近地表历史采空区为研究对象,开展采空区综合探查与稳定性分析研究。通过地表及井下现场调查,结合瞬变电磁探测、无人机倾斜摄影、卫星遥感影像分析和钻探验证等方法,对近地表采空区分布特征、异常区域性质及地表变形特征进行了调查分析。结果表明,矿区浅部采空区主要分布于历史采矿影响范围内,地表塌陷、废弃硐口与早期采掘工程具有较好的空间对应关系;瞬变电磁探测发现的局部异常经钻探验证后,部分为构造破碎带,部分为尾砂充填采空区,验证了物探异常解释的可靠性。基于探查结果建立典型采空区二维数值模型,对采空区围岩位移及应力分布特征进行了分析。计算结果显示,采空区变形主要集中于采空区周边及充填体与围岩接触区域,顶板及边界区域存在一定应力集中现象,但未出现明显贯通性破坏区域,现状条件下采空区整体保持稳定。在此基础上,进一步开展地震作用下尾砂充填体动力响应分析,结果表明充填体内部存在一定程度的超静孔隙水压力累积,但超孔压比明显低于液化判别标准,未形成明显液化区域。研究结果可为类似金属矿山近地表历史采空区探查、稳定性评价及安全管理提供参考。

     

    Abstract: To address the unclear locations, complex spatial relationships, and difficulty in accurately determining the stability of historical goafs formed by long-term underground mining, an integrated investigation and stability analysis was conducted on near-surface historical goafs in a metal mine. Surface and underground field investigations, transient electromagnetic surveys, UAV oblique photogrammetry, satellite remote sensing analysis, and drilling verification were jointly used to characterize the distribution of near-surface goafs, the nature of anomalous areas, and surface deformation. The results indicate that the shallow goafs are mainly distributed within the areas affected by historical mining, and surface subsidence areas and abandoned adit portals show good spatial correspondence with early mining workings. The anomalies identified by transient electromagnetic surveys were further verified by drilling. The verification results show that some anomalies correspond to structural fracture zones, while others correspond to tailings-filled goafs, demonstrating the reliability of the geophysical interpretation. Based on the investigation results, a two-dimensional numerical model of a typical goaf was established to analyze the displacement and stress distribution characteristics of the surrounding rock. The results show that deformation mainly occurs around the goaf boundaries and at the interfaces between the backfill and surrounding rock. Although stress concentrations occur in the roof and boundary areas, no obvious through-going failure zones are observed, indicating that the goaf remains generally stable under current conditions. Furthermore, the dynamic response of the tailings backfill under seismic loading was analyzed. The results show that excess pore water pressure accumulates to some extent within the backfill. However, the excess pore pressure ratio remains significantly below the liquefaction criterion, and no obvious liquefaction zone forms. The findings provide a reference for goaf investigation, stability evaluation, and safety management of near-surface historical goafs in similar metal mines.

     

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