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深部碎裂岩体巷道变形破坏机制与支护效应连续−非连续分析

Continuous-discontinuous analysis of deformation failure mechanism and supporting effect of roadway in deep fractured rock mass

  • 摘要: 金川二矿深部碎裂岩体具有“岩块强度高, 岩体强度低”的显著特点, 巷道围岩具有显著的大变形特征, 导致喷锚网或衬砌等支护结构破坏频繁, 严重威胁采矿生产安全。以该矿深部巷道现场工程为背景, 首先, 通过现场调查和实测确定该矿深部巷道围岩具有典型层状、碎裂状和复合结构特征, 冒落和底臌为典型的破坏形式; 其次, 结合室内试验和现场监测数据, 基于连续−非连续数值模拟分析方法(FDEM)提出一种可破Voronoi块体模型和离散裂隙网络模型模拟巷道开挖过程, 捕获围岩损伤破裂特征; 最后, 结合实体单元和锚杆单元模拟支护结构响应, 探讨深部碎裂岩体变形破坏机制和支护效应。研究结果表明, 结构面间距和倾角显著影响应力释放区的位置和压力拱的形成, 导致围岩变形各向异性和破裂非均匀性; 锚杆、混凝土喷层+锚杆及U型钢拱架+锚杆3种支护结构对于限制围岩变形具有显著差异性, 加入锚杆和衬砌能有效抑制冒落区, 限制顶拱位移, 但不能有效抑制底板隆起; 超前注浆、加长锚杆和钢拱架是控制深部碎裂岩体巷道大变形的重要措施。研究结果可为深部碎裂岩体巷道变形控制与支护设计提供理论参考。

     

    Abstract: The deep fractured rock mass of Jinchuan No. 2 Mine has the remarkable characteristics of high-strength rock and low-strength rock mass. The surrounding rock shows significant large deformation behaviour, which frequently leads to the destruction of supporting structures, such as spray anchor net or lining and seriously, threatening the mining activities. Based on the field work in deep roadway of Jinchuan No. 2 Mine and the continuous-discontinuous numerical analysis method, this study discussed the large deformation mechanism and supporting effect. First, the field investigation reported that the surrounding rock had typical layered, fractured and mixed structure characteristics, and caving and bottom drum were typical failure mode. Next, based on laboratory tests, field monitoring data, the Voronoi-based breakable block model and the discrete fracture network model, the roadway excavation processes were simulated to capture the damage and fracture characteristics of surrounding rock. Finally, the support structure responses were simulated using the solid element and rockbolt element. The numerical results show that the spacing and dip angle of joints significantly influenced the location of stress relief zone and the formation of pressure arch, which results in deformation anisotropy and fracture heterogeneity. There were significant difference in limiting the deformation of surrounding rock for the supporting structures of rockbolt, spray layer+rockbolt and U-shaped steel arch+rockbolt. The rockbolt and lining could effectively restrain the caving zone and limit the displacement of top arch, but could not effectively restrain the floor uplift. The advance grouting, lengthening rockbolt and steel arch were important measures to control the large deformation. This study can provide theoretical support and practical guidance for deformation control and support design of roadway in deep fractured rock mass.

     

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