生态脆弱区采煤扰动下包气带水分再分布影响因素敏感性分析

Sensitivity analysis of factors influencing water redistribution in vadose zones under coal mining disturbance in ecologically vulnerable areas

  • 摘要:
    目的 采煤扰动下矿区包气带水分将再分布,其再分布影响因素敏感性对于矿区生态地质环境重建和经济可持续发展意义重大。
    方法 以陕北榆神风沙滩地矿区为工程背景,在分析采煤扰动下包气带水分再分布的主要影响因素基础上,基于正交试验建立18组采煤扰动下包气带水分再分布COMSOL Multiphysics数值模型,理论上获得采煤扰动恢复至采煤前阶段距地表6.2、7.0、7.8 m深度监测线处的平均饱和度,并通过极差分析和多元线性回归分析,厘清采煤扰动下包气带水分再分布影响因素敏感性,进而运用层次分析法确定各主要影响因素的权重。
    结果和结论  (1)分别从地层结构、水文地质条件和采矿条件等角度确定采煤扰动下包气带水分再分布的主要影响因素:砂质壤土和砂质黏土厚度比值a、初始孔隙率p、初始裂隙数量l、包气带基质渗透系数K1、裂隙渗透系数K2、煤层采高b。(2)采煤扰动下包气带水分再分布总体上受砂质壤土和砂质黏土厚度比值a和裂隙渗透系数K2影响较大;而受初始裂隙数量l、煤层采高b和包气带基质渗透系数K1的影响较小;综合比较后得出敏感性大小排序为a>K2>p>b>l>K1。(3)根据正交试验极差分析和多元线性回归分析结果综合确定各因素敏感性排序后,利用层次分析法确定敏感性排列顺序的各主要因素的权重分别为:38.25%、25.04%、15.96%、10.06%、6.41%、4.28%;敏感性排序和权重排序一致,两者相互验证。研究成果对于我国西部生态脆弱区生态安全格局重构、绿色矿山建设具有重要意义。

     

    Abstract:
    Objective Coal mining-induced disturbance leads to water redistribution in the vadose zones of mining areas. The sensitivity analysis of the factors influencing this redistribution holds critical significance for the reconstruction of eco-geological environments and the sustainable economic development in mining areas.
    Methods Against the engineering background of the Yushen mining area characterized by wind-blown sandy terrain in northern Shaanxi Province, this study analyzed the primary factors influencing water redistribution in the vadose zone under coal mining disturbance. Accordingly, 18 COMSOL Multiphysics numerical models for water redistribution in the vadose zone under coal mining disturbance were constructed through orthogonal experiments. Using these models, the theoretical average saturation along three monitoring lines at burial depths of 6.2 m, 7.0 m, and 7.8 m was derived to recover the coal mining disturbance of the pre-mining stage. Through the range analysis and multiple linear regression analysis, this study clarified the sensitivity of the factors influencing water redistribution in the vadose zone under coal mining disturbance and further determined the weights of the primary influential factors using the analytic hierarchy process (AHP).
    Results and Conclusions From the perspective of stratigraphic structure, hydrogeological conditions, and mining conditions, the primary factors influencing water redistribution in the vadose zone under coal mining disturbance included the ratio of the sandy loam thickness to the sandy clay thickness (a), initial porosity (p), initial number of fractures (l), the matrix permeability coefficient of the vadose zone (K1), fracture permeability coefficient (K2), and coal seam mining height (b). Under coal mining disturbance, the overall water redistribution in the vadose zone was primarily influenced by factors a and K2, along with minor influence from factors l, b, and K1. Based on the range analysis and multiple linear regression analysis of the orthogonal experimental results, the sensitivity of these factors decreased in the order of a, K2, p, b, l, and K1. Following the sensitivity ranking of these factors, the weights of the primary factors were determined at 38.25% (a), 25.04% (K2), 15.96% (p), 10.06% (b), 6.41% (l), and 4.28% (K1) using the AHP. The sensitivity ranking was consistent with the weight ranking, with both substantiating each other. The results of this study hold great significance for reconstructing the ecological security patterns and constructing green mines in ecologically vulnerable areas within western China.

     

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