综采坚硬顶板分段水力压裂卸压护巷技术研究

Investigation on the Pressure Relief and Roadway Support by Segmented Hydraulic Fracturing Technique in Hard Roof of Fully Mechanized Mining

针对富家凹煤业11205工作面顺槽受相邻工作面采动效应引起的围岩变形问题,分析了矿压显现原因及水力切顶卸压机制,提出利用水力压裂作为预处理措施来缓解煤矿开采引起的采动应力,并开展了现场工业试验,验证切顶卸压效果。研究结果表明:采用水力切顶卸压可有效削弱坚硬顶板的强度、降低矿压显现,顶板窥视发现压裂后孔内壁裂缝明显增多,说明水力压裂效果良好。在11205综采工作面运输顺槽布置监测点,现场监测数据显示,水力压裂后,巷道顶板与两帮变形分别减少了54.8%和50%。数值模拟结果显示,压裂后回采顶板及时垮落,应力得到释放,煤柱上方应力明显减小,由30 MPa减少到17 MPa,证明了压裂弱化作用的有效性。定向分段水力压裂技术降低了采动应力对护巷煤柱的冲击。

Targeting the issue of surrounding rock deformation in the 11205 working face groove of Fujiawa Coal Mine caused by the mining-induced effect from adjacent working faces,the causes of mining pressure manifestation and the hydraulic roof cutting pressure relief mechanism was analyzed,using hydraulic fracturing as a pre-treatment measure to alleviate mining induced stress in coal mines was proposed,and on-site industrial experiments were conducted to verify the effect of roof cutting pressure relief.The results demonstrate that hydraulic fracturing effectively weakens the strength of the hard roof and reduces mining pressure manifestations.Observations of the roof reveal that the number of cracks within the borehole walls increases significantly after fracturing,indicating a favorable fracturing effect.By setting up monitoring points in the transportation groove of the 11205 fully mechanized working face,field monitoring data show that deformations of the roadway roof and two sides are reduced by 54%and 50%,respectively.Additionally,the roof stress decreases from 30 MPa to 17 MPa,confirming the effectiveness of the fracturing-induced weakening.The directional segmented hydraulic fracturing technique can effectively reduce the mining-induced stress impact on the protective coal pillar.