超高边坡开挖对既有隧道衬砌结构安全影响分析

Influence Analysis of Excavation of Ultra-high Slope on Lining Structure Safety of Existing Tunnel

以某临近既有隧道的道路改建高挖方边坡工程为研究对象,利用有限差分软件模拟分析了边坡逐级开挖过程中隧道衬砌结构变形与主应力的变化规律,计算了衬砌结构安全系数进而评价隧道结构稳定性,并结合现场测量数据分析验证仿真模拟的可靠度。结果表明:随着超高边坡逐级开挖,隧道衬砌结构各部位变形均增大,最大主应力从压应力变为拉应力而最小应力均表现为压应力;安全系数大幅度降低,Ⅲ阶段右拱腰存在局部破坏风险,Ⅳ阶段拱顶与左边墙易受拉破坏;模拟值高于实际值,减少边坡爆破施工可确保隧道运营阶段的安全性,可为相似工程提供一定参考价值。

Taking a high excavation slope of a road reconstruction project near an existing tunnel as a research object,this paper used finite difference software to simulate and analyze the variation law of the deformation of the tunnel lining structure and the principal stress during the step-by-step excavation of the slope.The safety factor of the lining structure was calculated to evaluate the stability of the tunnel structure,and the reliability of the simulation was verified by the field data.The results showed that with the excavation of the ultra-high slope,the deformation of each part of the tunnel lining structure increased,and the maximum principal stress became tensile stress from compressive stress while the minimum stress was compressive stress.The safety factor was significantly reduced.There was a partial failure risk at the right hance in stageⅢ,and the vault and left side wall were vulnerable to tensile failure in stageⅣ.The simulated value was higher than the actual value,and reducing the blasting construction of the slope can ensure the safety of the tunnel operation.This paper can provide a certain reference for similar engineering.