煤矿临空巷道水力压裂防冲技术应用

Application of hydraulic fracturing technology for rockburst prevention in coal mine roadway adjacent to gob area

  • 摘要: 【目的】煤矿临空巷道受叠加应力及采动影响,发生冲击的危险性随之增加,故以蒋家河煤矿ZF1412工作面回风顺槽水力压裂为例开展技术研究。【方法】研究表明,回采期间基本顶“OX”破断,临空侧悬顶弧形三角区不易垮落;在回风顺槽4号煤层顶板15 m的砂岩层中布置3个压裂孔进行压裂试验,确定了岩石起裂压力及水力做功下主次裂缝扩展规律。【结果及结论】通过现场监测结果表明,端头支架支撑力明显减小,90#液压支架支撑力同比下降了12.2 MPa,压裂水平半径约为15 m,裂缝网络为椭球体,沿压裂孔呈轴对称分布,水力压裂有效切断了工作面与临空侧煤柱连接,降低了临空侧煤柱压力,从而防止回采期间临空侧保护煤柱因压力过大产生回风顺槽巷道变形甚至诱发冲击危险。

     

    Abstract: Coal mine roadway adjacent to the goaf is subjected to superimposed stress and mining influence,increasing the risk of rockburst. This paper conducts a technical study based on the hydraulic fracturing in the return airway of the ZF1412 working face in Jiangjiahe Coal Mine. The research shows that during the mining period,the main roof undergoes “ O-X”type breakage,and the arc-shaped triangular roof area on the goaf-side is prone to forming a cantilever structure that does not easily collapse. In the sandstone layer 15 meters above the No. 4 coal seam in the return airway,three fracturing holes were arranged for fracturing experiments,determining the rock initiation pressure and the propagation patterns of primary and secondary fractures under hydraulic action. On-site monitoring results indicate that the support resistance of the support at the roadway end significantly decreased,with the support resistance of the No. 90 hydraulic support reduced by 12. 2 MPa compared to pre-fracturing levels. The effective horizontal radius of the fracturing was approximately 15 meters,and the fracture network formed an ellipsoidal shape,exhibiting axisymmetric distribution around the fracturing holes. Hydraulic fracturing effectively severed the connection between the working face and the goaf-side coal pillar,reduced the pressure on the goaf-side coal pillar,and prevented deformation of the return airway and potential rockburst hazards caused by excessive pressure on the protective coal pillar adjacent to the goaf during mining.

     

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