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陕北浅埋煤层似膏体充填条带开采参数研究及应用

Study and application of paste-like filling mining parameters of shallow buried coal seam in Northern Shaanxi

  • 摘要: 陕北地区生态环境脆弱、水资源缺乏,同时该区域又赋存着丰富的浅埋煤层资源。为解决采煤引起的水资源流失问题,提出了在陕北“保水区”应用风积沙似膏体充填条带置换开采技术。基于弹性地基理论,构建了条带开采的煤柱-顶板力学模型,推导出了采后顶板下沉的挠曲公式,并结合Winkler地基理论及极限强度准则,计算出条带工作面合理的采宽及留宽。 针对由风积沙作为骨料,由粉煤灰、水泥作为胶结料,与水经充分混合搅拌形成的充填体,经实验室合理配比试验,得出了最佳的充填材料配比及强度指标,并从微观层面揭示了充填体内结晶体穿插成网程度决定不同龄期充填体强度的机理。以榆林市上河煤矿为实例,通过对该矿3216工作面开采实践, 数值模拟得到了开采过程中隔水层运移规律。研究结果表明:采后隔水层沉降量最大值为27.9 mm,表明开采过程隔水层保持稳定,采场覆岩结构得到了较好的控制。现场工业性实验表明,条带开采采空区充填效果良好,现场监测覆岩位移变化不显著,总体呈现出下部岩层位移>中部岩层位移>上部岩层位移。上河煤矿通过成功实践条带充填置换开采技术保证了覆岩的良好稳定性,大幅降低了覆岩导水裂隙带发育高度,3216工作面充填后涌水问题得到根本解决,并大幅提高了上河煤矿煤炭采出率,对陕北保水采煤具有良好的借鉴和推广应用价值。

     

    Abstract: The ecological environment is fragile and water resources are scarce in northern Shaanxi,and abundant shallow coal seam resources exist in this area. In order to solve the problem of water resources loss caused by coal mining,the paper proposes to apply the technology of replacement of eolian sand paste-like filling strip in the "water-retaining area" of Northern Shaanxi. Based on the theory of elastic foundation,the mechanical model of coal pillar roof in strip mining is established,and the deflection formula of the roof after mining is deduced. Combined with Winkler foundation theory and ultimate strength criterion,the reasonable mining width and reserved width of strip working face are calculated. The study results show at the backfill formed by the mixture of aeolian sand as aggregate,fly ash,cement,as binder and water. Based on the laboratory cross matching experiment,the optimal filling material ratio and strength index are obtained,and at the micro level,the mechanism that the strength of backfill at different age is determined by the degree of crystal interpenetrating into mesh is revealed. Taking Shanghe coal mine in Yulin City as an example,through the numerical simulation of the movement law of the aquiclude in the mining process of the experimental No.3216 working face,it shows that the maximum value of the settlement of the aquiclude after mining is 27.9 mm,which indicates that the aquiclude keeps stable in the mining process and the overiying rock structure of the stope is well controlled. The industrial experiments show that the filling effect of the strip gobs is good,and the displacement of overburden rock is not obvious. In general,lower strata displacement>middle strata displacement>upper strata displacement. Through successful practice of strip filling replacement mining technology,the good stability of overburden rock was ensured in Shanghe Coal Mine,the development height of water-conducting fracture zone in overburden is greatly reduced,the problem of water gushing after filling of No.3216 working face is fundamentally solved,and the recovery rate of Coal in Shanghe Coal Mine is greatly improved in Northern Shaanxi.

     

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