1.School of Mining Engineering,Liaoning Technical University,Fuxin ,China； 2.CCTEG Shenyang Research Institute,Shenyang ,China

保护效果分析是保护层开采的关键技术之一,体积变形与渗透特性是评价保护效果的核心指标。以长平矿3号煤层下保护层开采防治瓦斯灾害为工程背景,基于实验室相似模拟研究平台,根据体积应变特征研究被保护层渗透特性演化规律,提出了"四定点围域面积"分析方法,应用其研究被保护层在采动应力变化条件下体积应变特征;建立了体积应变与渗透率相关性数学模型,揭示了被保护层卸压煤岩体渗透特性演化规律。研究成果表明:下保护层工作面推进过程中,被保护层煤体体积应变在空间上依次呈∧型、π型和马鞍型分布;在保护层开采过程中被保护层最大压缩变形率为0.723%,最大膨胀变形率为0.77%。下保护层开采过程中,被保护层煤体渗透性演化规律总体呈马鞍型发展趋势,被保护层在拉伸蠕变阶段渗透率最大增加129%,在采空区覆岩压缩密实阶段渗透率平均增加82%,在压缩稳定后渗透率平均增加43%。研究成果揭示了长平矿下保护层开采过程中被保护层渗透特征演化规律,为被保护层卸压效果评价、卸压瓦斯治理方案确定提供了理论依据。

The protection effect analysis is one of the key technologies of mining protective coal seam,and volumetric strain and permeability are the core indexes for evaluating the protective effect.Taking No.3 coal seam mining protective coal seam and gas disaster prevention of Changping Mine as the project background,the volumetric strain feature was applied to study the protected coal seam evolution rule of permeability on laboratory similarity simulation study platform. The method of “four point surrounded area” was put forward,which was applied to study the feature of volumetric strain in protected coal seam under the condition of mining stress changing. The mathematical model correlation between volumetric strain and permeability was established,and the permeability evolution of pressure-relief coal and rock mass during mining protective coal seam was revealed. The research results showed that the volumetric strain of protected coal seam in the space showed ∧ shape,π shape and saddle shape during the process of lower protective coal seam; the maximum compressive deformation rate of protected coal seam was 0.723% and the maximum expansion rate was 0.77% during the process of mining protective coal seam. During lower mining protective coal seam,the permeability evolution rule of protected coal seam showed saddle shape,the permeability of protected coal seam in tensile creep phase reached up to 129%,the permeability reached up to 82% on average in the compaction of the overlying strata in the goaf,the permeability increased by 43% after compression on average. The research results revealed the evolution feature of permeability of protected coal seam during mining protective coal seam under Changping Mine and provided theoretical basis for protected coal seam about the pressure-relief effective evaluation and pressure-relief gas extraction scheme.

国家自然科学基金青年科学基金资助项目(51504127)；辽宁省煤炭资源安全开采与洁净利用工程研究中心开放基金资助项目(NTU17KF06)；