浅埋近距离煤层工作面过煤柱开采强矿压危险性评价

Hazard assessment of strong mine pressure at working face crossing coal pillars in shallow closely spaced coal seams

  • 摘要: 浅埋近距离煤层群下煤层开采过上覆遗留煤柱时,易诱发以顶板台阶下沉或压架为特征的强矿压灾害,其危险性定量评价是现场控制的难题。以神东矿区为工程背景,提出了浅埋近距离煤层工作面过煤柱开采强矿压危险性评价方法。基于过煤柱开采的“倒梯形覆岩—间隔岩层”耦合顶板结构力学模型,辨识出间采比、煤柱与工作面夹角、间隔岩层稳定性等9项关键指标,构建了包含地质条件、煤柱属性、工程参数的三级递阶评价指标体系,并建立了各指标的四级量化分级标准(弱、一般、中等、高危险);采用层次分析法计算各评价指标权重,合成权重排名前3位的依次为间采比、煤柱与工作面夹角和间隔岩层稳定性;分别采用加权求和法和模糊综合评价法对过煤柱开采强矿压危险性进行评价,并分析2种评价方法的适用性,结果表明模糊综合评价法的最大隶属度原则会弱化非主导等级的潜在风险信息,因此推荐以加权求和法作为主评价模型,模糊综合评价法作为辅助校验模型。通过神东矿区6个典型过平行煤柱工作面的实测数据验证了该评价方法的合理性。

     

    Abstract: When lower seams in shallow closely spaced coal seam groups are mined beneath overlying residual coal pillars, strong mine pressure hazards characterized by step subsidence of the roof or support crushing can readily occur, and their quantitative hazard assessment is difficult for field control. With Shendong mining area as the engineering background, a method was proposed for assessing strong mine pressure hazard at working faces crossing coal pillars in shallow closely spaced coal seams. Based on a mechanical model of the coupled roof structure comprising inverted-trapezoidal overburden and interburden during coal pillar crossing, nine key indicators, including inter-mining ratio, angle between coal pillar and working face, and interburden stability, were identified; a three-level hierarchical evaluation system encompassing geological conditions, coal pillar attributes, and engineering parameters was constructed; and four-level quantitative classification criteria (weak, general, medium, and high hazard) were established for the indicators. The Analytic Hierarchy Process was used to calculate the weights of the evaluation indicators, and the top three indicators by composite weight were inter-mining ratio, angle between coal pillar and working face, and interburden stability, in descending order. The weighted summation method and fuzzy comprehensive evaluation method were used separately to assess strong mine pressure hazard during coal pillar crossing, and the applicability of the two methods was analyzed. The results showed that the maximum membership principle of fuzzy comprehensive evaluation would weaken potential risk information from non-dominant grades. Therefore, the weighted summation method was recommended as the primary evaluation model and fuzzy comprehensive evaluation as an auxiliary validation model. The rationality of the proposed method was verified using field-measured data from six typical working faces crossing parallel coal pillars in Shendong mining area.

     

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