Floor deformation control for roof cutting and pressure relief in gob-side entry retaining of deep buried mines
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摘要: 目前有关巷道底鼓的研究与实践主要探讨巷道底板的变形机理及控制技术,对沿空留巷切顶卸压前后底板力学分析不全面。针对该问题,基于煤体分区破坏特征构建了切顶前后巷道围岩和底板力学模型,分析实体煤、巷旁支护及采空区对底板的作用,获得切顶前后巷道底鼓解析解,得出巷旁煤帮弹塑性区、巷道支护体及顶板下沉区底板所受载荷共同影响巷道底鼓量大小。采用数值模拟验证切顶卸压前后沿空留巷围岩破坏特征、应力分布及底鼓量变化,结果表明:切顶卸压技术可有效缩小巷道实体煤侧面及顶部的破坏区域,维持巷道围岩结构稳定;巷道底板最大应力、巷旁支护阻力、巷道底鼓量均下降,平均降幅分别为25.78%,56.14%,54.07%。现场应用结果表明,厚硬顶板沿空留巷底鼓量由709.345 1 mm降至320.965 8 mm,切顶卸压技术可以优化巷道围岩应力结构,抑制巷道底鼓,有效改善底板破坏情况。Abstract: Currently, research and practice on roadway floor heave mainly explore the deformation mechanism and control technology of roadway floor. The mechanical analysis of floor before and after roof cutting and pressure relief in gob-side entry retaining is not comprehensive. In order to solve the above problem, mechanical models of the surrounding rock and floor of the roadway before and after roof cutting are constructed based on the features of coal partition failure. The effects of solid coal, roadway support, and goaf on the floor are analyzed. The analytical solutions for the floor heave of the roadway before and after roof cutting are obtained. The conclusion is drawn that the elastic-plastic zone of the coal wall beside the roadway, the support structure of the roadway, and the load on the floor of the subsidence zone jointly affect the magnitude of the roadway floor heave. Numerical simulation is used to verify the features of rock mass failure, stress distribution, and changes in floor heave in gob-side entry retaining before and after roof cutting and pressure relief. The results show that roof cutting and pressure relief technology can effectively reduce the damage area on the solid coal side and top of the roadway, and maintain the stability of the roadway rock mass structure. The maximum stress of the roadway floor, the resistance of the roadway side support, and the amount of roadway floor heave all decrease, with an average decrease of 25.78%, 56.14%, and 54.07%, respectively. The on-site application results show that the amount of floor heave of thick hard top in gob-side entry retaining is reduced from 709.345 1 mm to 320.965 8 mm. The roof cutting and pressure relief technology can optimize the stress structure of the surrounding rock of the roadway, suppress the floor heave of the roadway, and effectively improve the floor damage.
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表 1 各岩层物理力学参数
Table 1. Physical and mechanical parameters of each rock formation
岩性 弹性模
量/GPa抗拉强
度/MPa内摩擦
角/(°)泊松比 容重/
(kN·m−3)黏聚
力/MPa细砂岩 42 6.50 25 0.16 27.0 5.4 粉细砂岩 18 2.35 31 0.21 26.0 3.8 中砂岩 12 2.11 28 0.22 26.2 3.3 泥岩 6 1.47 24 0.21 22.5 2.4 1煤 0.8 1.20 21 0.35 13.8 1.8 砂质泥岩 9 2.91 24 0.23 25.2 2.8 -
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