大断面软弱破碎围岩煤巷演化规律与控制技术

随着矿井开采深度与巷道断面尺寸的增加,煤巷围岩松软、破碎程度越来越严重,煤巷顶板冒落的危险性增大,大断面煤巷支护与维护难度随之增加。基于煤巷围岩松动圈测试与分析,揭示了大断面软弱破碎围岩煤巷变形破坏特征;采用FLAC3D模拟研究了不同巷道布置方式、顶煤厚度、巷道高宽比及侧压系数等条件下大断面软弱破碎围岩煤巷开挖后围岩变形特征、塑性区演化规律及应力分布特征,为煤巷优化布置、合理支护方案与参数的选取提供了理论依据;针对大断面软弱破碎围岩煤巷变形破坏特征与支护难点,提出了全断面锚网索喷初次支护、高预应力锚索与锚注二次加固组成的"三锚"联合支护技术方案,采用数值模拟分析与相似材料模型试验,验证了该方案的合理性与围岩控制效果,并进行了井下工业性试验。监测结果表明,采用"三锚"联合支护技术,有效地控制了大断面软弱破碎围岩煤巷的大变形与底臌,维持了煤巷围岩与支护结构的稳定及安全。

Evolution law and control technology of surrounding rock for weak and broken coal roadway with large cross section

With the increase of mining depth and the cross section size of roadway，the soft and crushing degree of roadway surrounding rock becomes serious，and the risk of roadway roof caving increases as well，which make the support and maintenance of big cross section coal roadway become difficult.Based on the surrounding rock loose circle test and analysis，the deformation and failure characteristics of weak and broken coal roadway with large cross section were revealed.Roadway deformation characteristics，the evolutionary law of plastic zone and the characteristics of surrounding rock stress were simulated by FLAC3D under different mining roadway layouts，mining thicknesses，the height-width ratios of roadway and the coefficients of lateral earth pressure.With the work above，the basis for the roadway layout optimization，and the selection of reasonable support pattern and parameters were provided.According to the characteristics of deformation and failure and the difficulties in supporting the roadway，the “three anchor” combination supporting scheme was put forward，i.e.，bolting with wire mesh and shotcreting as the first step support，the high prestressed anchor and bolting-grouting as the second step support.Using numerical simulation analysis and similar material model test，the rationality of the scheme and the effect of surrounding rock control were verified，and the underground industrial tests were carried out.The result of monitoring shows that the roadway large deformation and bottom drum can be effectively controlled with the “three anchor” combined supporting technology，and the stability and safety of coal roadway surrounding rock and supporting structure can be ensured.It is an effective control technology for surrounding rock in coal roadway.