双线盾构隧道斜交下穿对高速公路的影响

为研究盾构隧道斜交下穿施工对既有高速公路工程的影响,以某城市轨道交通盾构下穿工程为背景,采用FLAC3D进行盾构施工三维数值模拟,分析了双线盾构施工对公路路面、路堑边坡的影响规律,评价了施工方案的安全性。结果表明：盾构斜交下穿时,路面沉降呈现三维非对称特征,在公路横断面方向,沉降曲线呈现左低右高的线性规律,在公路纵断面方向,沉降曲线呈现左高右低的不对称“V”形,且横断面方向沉降总是大于纵向沉降;边坡竖向位移大于水平位移,以沉降变形为主,开挖面距边坡坡脚水平距离约为2倍洞径时,边坡位移显著增加,该区段为施工强影响区;双线盾构贯通后,路面最大沉降值为3.15mm,纵向沉降变化率为0.0094% ,边坡最大水平位移为1.2mm,三者均小于变形控制标准,公路路基、边坡无塑性区出现,处于弹性状态,盾构下穿施工对既有高速公路影响较小。研究结果可为类似盾构下穿工程提供参考。

Influence of a Double Line Shield Tunnelling Obliquely Underpass Expressway

In order to study the influence of a shield tunnel oblique underpass construction on the existing expressway project, taking the shield tunneling project of an urban rail transit as the background, three dimensional numerical analysis of shield construction was carried out by using FLAC3D. The influence of shield tunnel construction on road surface and cutting slope was studied, and the safety of construction scheme was evaluated. The results show that: the settlement of the road surface presents three-dimensional asymmetric characteristics when the shield is obliquely underpass. In the direction of cross section, the settlement curve presents a linear law of low left and high right, and in the longitudinal direction, the settlement curve presents an asymmetrical "V" shape with high left and low right. The settlement in the direction of cross section is always greater than that in the longitudinal direction. The vertical displacement of the slope is larger than the horizontal displacement, and the main deformation is settlement. When the horizontal distance between the shield excavation face and slope toe is about 2 times of the tunnel diameter, the slope displacement increases significantly, and this section is a strong excavation influence area. After the double line shield tunneling, the maximum settlement of the pavement is 3.15mm, the longitudinal settlement change rate is 0.0094%, and the maximum horizontal displacement of the slope is 1.2mm, all of them are less than the deformation control standard. Highway pavement and slope are in elastic state, no plastic zone appears. The shield underpass construction of this project has little impact on the existing expressway. The research results can provide reference for similar shield underpass projects.