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    跨采软岩巷道变形破坏机理及注浆加固围岩控制研究

    Research on deformation and failure mechanism and grouting reinforcement technology of surrounding rock control in soft-rock cross-cut mining roadway

    • 摘要: 针对上覆工作面开采影响后底板软岩巷道围岩控制难题,以某煤矿263采区跨采底板南翼运输上山为研究背景,通过现场监测、理论分析、数值模拟相结合的研究方法,分析了上覆工作面回采过程中底板岩层应力分布及巷道围岩变形特征。研究结果表明:受跨采工作面动压影响,南翼运输上山围岩破坏严重,实测顶板破裂范围3.55 m,两帮2.91 m,因围岩破裂范围超过了锚杆长度,原支护体系无法对巷道围岩起到有效的锚固作用,必须进行补强加固支护。采用极限平衡理论计算得到263采区底板岩体塑性区深度为22.4 m,表明南翼运输上山的大部处于上部263采区开采形成的底板破坏区域范围之内。此外,通过数值模拟计算,分析了上覆工作面不同推进距离下跨采软岩巷道围岩变形破坏情况,揭示了跨采软岩巷道围岩的变形破坏机理的演化规律。针对南翼运输上山围岩特别软弱破碎的特点,研制了具有良好流动性、快速初凝和高膨胀性的UFJC注浆材料,试验确定了材料配比并进行了性能测试。针对现场实际情况,提出了“深浅孔注浆+补强锚杆(索)”加固支护方法,南翼运输上山补强加固后20~40 d内围岩变形趋于稳定,稳定后的巷道顶底板平均移近量仅为134 mm,两帮平均移近量仅为114 mm,巷道围岩整体变形较小,补强加固支护取得了良好控制效果。

       

      Abstract: To address the challenge of surrounding rock control in floor soft-rock roadways affected by the mining of an overlying working face, this study takes the cross-cut mining over the south-wing main haulage rise in the floor of the 263 mining area in a coal mine as its research background, through a combination of field monitoring, theoretical analysis and numerical simulation, the stress characteristics of the floor strata and the deformation characteristics of the roadway surrounding rock during mining of the overlying working face were analyzed. The research results indicate that under the influence of dynamic pressure from the cross-mining face, the surrounding rock of the south-wing main haulage rise has been severely damaged. The measured fracture range in the roof is 3.55 m, and that in the sidewalls is 2.91 m. As the extent of surrounding rock failure exceeds the length of the anchor bolts, the original support scheme fails to effectively anchor the surrounding rock, making reinforcement support imperative. Based on limit equilibrium theory calculations, the failure depth of the floor rock mass in the 263 mining area reaches 22.4 m, placing the majority of the south-wing main haulage rise within the floor failure zone induced by the mining activities in the overlying 263 mining area. Furthermore, numerical simulations were conducted to analyze the deformation and failure of the roadway surrounding rock under different advance distances of the cross-cut mining face, thereby revealing the deformation and failure mechanism as well as the spatiotemporal evolution law of the surrounding rock in the cross-mined soft rock roadway. Considering the exceptionally soft and fractured nature of the surrounding rock in the south-wing main haulage rise, a novel UFJC grouting material characterized by excellent fluidity, rapid initial setting and high expansibility was developed. The optimal mixing ratio was determined through experimental testing, and its performance was systematically evaluated. In response to the actual site conditions, a reinforcement support method combining deep and shallow hole grouting with supplementary anchor bolts (cables) was proposed. Following the reinforcement of the south-wing main haulage rise, the deformation of the surrounding rock tended to stabilize within 20 to 40 days, the average convergence of the roof and floor was only 134 mm and the average convergence of the two sidewalls was only 114 mm after stabilization, indicating minimal overall deformation of the roadway surrounding rock, and the reinforcement support scheme achieved satisfactory control effects.

       

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