软岩大变形隧道最优支护参数选择

Selection of Optimal Support Parameters for Large Deformation Tunnel in Soft Rock

目前国内外软岩隧道施工出现了大量变形问题,软岩隧道变形过大将无法实施二次支护,因此软岩隧道施工初期支护参数的设置至关重要。本研究构建了基于统一强度理论的应变软化模型,并结合松动圈理论计算得到锚杆最优支护参数的计算方法。依托软岩隧道A的实际施工,使用数值模拟和现场监测两种方式,验证最优支护参数计算方法的有效性。结果表明:支护参数优化之后,隧道围岩松动圈的拱顶厚度减少了45.4%,边墙厚度减小了43.5%,说明施加支护措施能够有效遏制松动圈的进一步扩散,并且效果明显。研究提出的软岩大变形隧道最优支护参数设计方法在理论推演和工程应用中均有效,可为软岩隧道初期支护措施设计提供一定思路。

At present, there are a lot of deformation problems in soft rock tunnel construction at home and abroad.If the deformation of soft rock tunnel is too large, it will not be able to implement secondary support.Therefore, the setting of support parameters in the initial stage of soft rock tunnel construction is very important.The strain softening model based on the unified strength theory is established, and the calculation method of the optimal support parameters is obtained by combining with the loose circle theory.Based on the actual construction of soft rock tunnel A,numerical simulation and field monitoring are used to verify the effectiveness of the optimal support parameters calculation method.The results show that, after the optimization of support parameters, the vault thickness of loose circle of tunnel surrounding rock is reduced by 45.4%,and the side wall thickness is reduced by 43.5%,which indicates that the application of support measures can effectively curb the further diffusion of loose circle, and the effect is obvious.The optimal support parameter design method of soft rock tunnel with large deformation proposed in this paper is effective in theoretical deduction and engineering application, which can provide some ideas for the design of initial support measures of soft rock tunnel.