考虑环间强度折减的顶管上穿对既有隧道结构变形影响分析

Analysis of Influence of Pipe Jacking on Deformation of Existing Tunnel Structure Considering Interring Strength Reduction

确定已建盾构隧道环间连接区域强度,对指导新建上穿隧道施工和已建隧道结构进行加固具有重要的指导意义。选定环间一定区域为强度折减区,管片结构混凝土弹性模量与折减系数的乘积作为该区域参数取值;借助软件依次开展不同折减系数工况下顶管上穿已建盾构隧道结构数值计算,对比分析了不同折减系数工况下隧道结构拱顶变形、环间错台以及应力特征。结果表明:已建隧道结构拱顶变形近似呈“正态分布”;折减系数取值过大或者过小时,存在已建隧道结构拱顶变形分布收敛现象;在一定范围内,随着折减系数减小隧道结构拱顶竖向位移分布曲线由“矮胖”向“高瘦”变化;当折减系数大于10^(-1)时,隧道结构最大拉应力、压应力受折减系数影响明显。

It is of great significance to determine the strength of the connection area between the rings of the existing shield tunnel for guiding the construction of the new overpass tunnel and the reinforcement of the existing tunnel structure.A certain area between the rings was selected as the strength reduction area,and the product of the elastic modulus of the concrete of the segment structure and the reduction coefficient was used as the parameter values of the area.By using software,the numerical calculation of the structure of the pipe jacking crossing the existing shield tunnel under different reduction coefficient conditions was carried out in turn,and the deformation of the vault,the dislocation between the rings,and the stress characteristics of the tunnel structure under different reduction coefficient conditions were compared and analyzed.The results show that the vault deformation of the existing tunnel structure shows an approximately normal distribution.When the value of the reduction coefficient is too large or too small,there is a convergence phenomenon of the vault deformation distribution of the existing tunnel structure.Within a certain range,the vertical displacement distribution curve of the tunnel structure vault changes from being“short and fat”to being“tall and thin”with the reduction coefficient decreasing.When the reduction factor is greater than 10^(-1),the maximum tensile and compressive stress of the tunnel structure is obviously affected by the reduction factor.