深部破裂围岩-锚杆支护时效特性及巷道长时稳定性分析

    Time-effect characteristics of bolt support in deep fractured surrounding rock and long-term stability analysis of roadway

    • 摘要: 深部巷道围岩在破裂时往往表现出明显的碎胀蠕变特征,锚网喷支护难以有效控制,导致围岩持续大变形或巷道大面积破坏,严重影响矿井的安全高效生产。深部巷道破裂围岩碎胀蠕变控制已是制约深地矿产资源安全开发的突出技术难题,为探究深部破裂围岩锚固体的蠕变机理与锚杆的长效作用机制,基于经典的Burgers蠕变模型,通过破裂度变量引入非线性黏壶元件,表征深部破裂围岩的非线性蠕变阶段,将弹性元件表征的锚杆与其并联,构建了深部破裂围岩锚固体的非线性蠕变本构模型,选取立方体试样在最后一级应力作用下的应变-时间曲线对深部破裂围岩立方体试样蠕变本构模型进行参数辨识;采用FLAC3D开展了深部破裂围岩巷道长时稳定性模拟分析,得到了深部破裂围岩变形-支护时效特性曲线,分析了不同锚杆长度和锚杆排距情况下巷道围岩与锚杆的时效相互作用,有效证明了深部巷道围岩变形具有明显的时效性,且锚杆、锚索等支护手段可以有效限制围岩的蠕变变形,同时揭示了埋深(应力水平)和侧压力系数(应力状态)对深部破裂围岩巷道变形和锚杆长时受力的影响规律,确定了锚杆在深部巷道的适用工况,表明锚杆支护具有自身的适应性。研究成果可为解决深部破裂围岩巷道长期稳控难题提供理论依据,对深地资源安全开发具有重要的理论指导与工程应用价值。

       

      Abstract: The surrounding rock of deep roadways often exhibits significant fragmentation and swelling creep characteristics during failure, making anchor mesh and shotcrete support ineffective. This leads to continuous large deformations of the surrounding rock or widespread damage to the roadway, severely affecting the safe and efficient production of mines. The control of swelling creep in fractured surrounding rock of deep roadways has become a prominent technical challenge restricting the safe development of deep mineral resources. To investigate the creep mechanism of anchor bodies in fractured surrounding rock and the long-term effectiveness of anchor bolts, a nonlinear viscous component is introduced to represent the nonlinear creep stage of deep fractured surrounding rock based on the classic Burgers creep model and fracture degree variable. A nonlinear creep constitutive model for the anchor body in deep fractured surrounding rock is established by combining the elastic component representation of anchor bolts in parallel. Parameter identification for the creep constitutive model of deep fractured surrounding rock cubic samples is conducted using strain-time curves under the final stress stage. FLAC3D is used to simulate and analyze the long-term stability of deep fractured surrounding rock roadways, producing deformation-support time characteristic curves. The interaction between the surrounding rock and anchor bolts under different anchor bolt lengths and spacing is analyzed, effectively proving that the deformation of deep roadway surrounding rock is time-effect. Moreover, anchor bolts, anchor cables, and other support measures can effectively limit the creep deformation of surrounding rock. The study also reveals the impact of burial depth (stress level) and lateral pressure coefficient (stress state) on the deformation of deep fractured surrounding rock roadways and the long-term force on anchor bolts. The findings identify the applicable working conditions for anchor bolts in deep roadways and indicate that anchor support has its own adaptability. The results provide a theoretical basis for solving the long-term control problems of fractured surrounding rock in deep roadways and have important theoretical and engineering application value for the safe development of deep mineral resources.

       

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