不同曲线半径盾构隧道施工扰动特性研究

Study on Construction Disturbance Characteristics of Shield Tunnel with Different Curve Radius

为了探究不同曲线半径盾构隧道施工的扰动特性,本文以与桥桩水平净距为3.6 m的急曲线电力盾构隧道为例,建立不同曲线半径(50 m、80 m、120 m、150 m)下的急曲线隧道侧穿桥桩的三维有限元模型,分析曲线半径变化对盾构隧道施工地层以及附近桩基扰动的影响。研究结果表明:当电力盾构隧道曲线半径从150 m减小到50 m时,管片衬砌的横向与竖向变形值均有所增大,同时管片衬砌结构的第一主应力基本保持不变,第三主应力数值略有增大,管片衬砌拱底和右拱腰是应力集中的地方,施工中应重点监测;地表沉降变形最大值约为1.30 mm,且最大值位置出现在曲线内侧,随着盾构隧道的曲线半径从150 m减小到50 m,地表沉降值增大0.17%~22.90%;急曲线盾构隧道近接侧穿施工引起桩基上部出现沉降变形,而下部出现上隆变形,随着曲线半径从150 m减小到50 m,桩基变形增大1.0~1.1倍,桩基最大沉降值约为1.2 mm,处于较低水平。

In order to explore the construction disturbance characteristics of shield tunnels with different curve radius,taking the large-curvature electric power shield tunnel with a horizontal clear distance of 3.6 m from the bridge piles as an example,the three-dimensional finite element models of the large-curvature tunnel with different curve radii(50m,80m,120m,150m) passing alongside bridge piles are established,and the influence of the curve radius on the disturbance of shield tunnel construction to the stratum and nearby pile foundations is analyzed. The results show that:when the curve radius of the electric power shield tunnel is reduced from 150 m to 50 m,the horizontal and vertical deformation values of the segment lining will increase.At the same time,the first principal stress of the segment lining structure will basically remain unchanged,and the third principal stress will slightly increase. The arch bottom and the right arch waist of the segment lining are the places where stress is concentrated,which should be well monitored in construction. The maximum surface settlement deformation is about 1.30 mm,and the maximum value appears on the inside of the curve. As the curve radius of shield tunnel decreases from 150 m to 50 m,the surface settlement increases by 0.17% ~ 22.90%.The passing alongside construction of large-curvature shield tunnel leads to the settlement deformation of the upper part of the pile foundations and the uplift deformation of the lower part. As the curve radius decreases from 150 m to 50 m,the deformation of pile foundations increases by 1.0 ~ 1.1 times. The maximum settlement of pile foundations is about 1.2 mm,which is at a low level.