大断面水工隧洞下穿既有公路隧道沉降影响分析

Analysis on settlement impact from under-crossing construction of large-section hydraulic tunnel through existing highway tunnel

针对某大断面水工隧洞下穿双线公路隧道工程,采用理论解方法,综合考虑大断面水工隧洞开挖引起的土层位移影响,提出了一种计算水工隧洞下穿引起上部既有公路隧道沉降位移值的计算方法。结合有限元模拟和实测数据对理论计算方法进行了可靠性验证,分析了既有双线公路隧道沉降影响范围大小及沉降位移规律。研究结果表明:三种方法所得公路隧道沉降曲线相互吻合,近似呈现正态分布,最大沉降值均位于分洪隧洞下穿轴线处;穿越引起的公路隧道下沉区域主要分布在穿越中心点两侧各23 m的范围,而在下沉区域外隧道出现局部的上浮变形;公路隧道总体沉降变形较小,结构稳定安全。

Aiming at the under-crossing construction of a large cross-section hydraulic tunnel through a double-line highway tunnel, the displacement of soil layer caused by the impact from the excavation of the large-section hydraulic tunnel is comprehensively considered with the relevant theoretical solution method, and then a method for the calculation of the settlement displacement of an existing highway tunnel caused by the under-crossing of a hydraulic tunnel is put forward herein. Combined with the finite element simulation and the related measured data, the reliability of the theoretical calculation method is verified, while the impacting range of the settlement and the law of the settlement displacement for the existing double-line highway tunnel are analyzed as well. The study result shows that the settlement curves of the highway tunnel obtained by three methods are consistent with each other and all approximately exhibit normal distributions. The maximum settlement values are all located at the under-crossing axis of the hydraulic tunnel, from which the subsidence area of the highway tunnel caused by the under-crossing is mainly distributed in the ranges of 23 m on both the sides of the crossing center point, while local uplift-deformation of the tunnel occurs outside the subsidence area. Generally, the total settlement deformation of the highway tunnel is less and the structure of it is stable and safe.