层状节理岩体隧道爆破裂纹扩展规律与参数优化研究

Blasting crack propagation patterns and parameters optimization in tunnel with layered jointed rock mass

  • 摘要: 钻爆法隧道施工过程中,层状节理岩体常导致拱顶和掘进工作面超欠挖等工程问题。针对这一问题采用理论分析、数值模拟和现场试验展开研究。理论分析表明,当节理结构面与断裂控制面相互垂直时,爆破能量能够得到最有效地利用。数值模拟结果显示,层状节理对爆炸应力波的传播具有显著的阻隔和干扰作用,大幅减弱爆炸能量在岩体内部的传递效果。层状节理对爆生裂纹的扩展起控制和导向作用,使裂纹扩展过程中出现偏移和分叉。现场爆破试验表明,炮孔之间设置空孔,能够有效控制和引导炮孔间裂纹的扩展方向,从而抑制拱顶、拱肩岩体的大面积垮落,避免了掘进工作面出现超欠挖现象。在此基础上,优化了隧道爆破参数及周边孔布设方案,为层状节理岩体隧道精准开挖提供有力的技术支撑。

     

    Abstract: During tunnel construction using the drilling and blasting method, layered jointed rock masses often pose engineering challenges such as over- and under-excavation of the crown and working face. The authors addressed these challenges via theoretical analysis, numerical simulation and field testing. Theoretical analysis revealed that blasting energy utilization is maximized when the jointed structural plane is perpendicular to the fracture control plane. The numerical simulation results shown that that layered joints significantly block and interfere with the propagation of explosive stress waves, reducing the transmission of explosive energy within the rock mass. They govern and direct the expansion of blast-induced cracks, inducing deviation and bifurcation. On site blasting tests have shown that setting empty holes between blast holes could govern and direct the expansion direction of cracks between blast holes, thereby suppressing large-scale collapse of the rock mass at the crown and spandrel, and avoiding over- and under-excavation at the working face. On this basis this study optimized tunnel blasting parameters and the layout scheme of surrounding holes, and provided robust technical support for the precise control of tunnel excavation in layered jointed rock masses.

     

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