基于应变监测的沉管隧道混凝土侧墙裂缝解析

摘要

As for an immersed tunnel that was constructed using cast-in-place concrete in two layers, vertical and diagonal cracks were regularly found on the sidewall above the horizontal cast-in-place interface with height of 2 m. In order to analyze the cause of this sidewall cracking, vibrating wire strain sensors were embedded in the bottom plate and sidewall of the immersed tunnel. The results show that:1) shrinkage strains were found at each monitoring point;2) shrinkage strains gradually increased from the middle to the end of the sidewall in the horizontal direction;and 3) the shrinkage strains gradually increased from the bottom to the top of the sidewall in the vertical direction. Based on the horizontal tensile stress and shear stress of some of the monitoring points, the plane stress state analyti⁃cal method was introduced to calculate the maximum principal stress and principal stress angle and to compare them with the development of cracks near the monitoring points. This analysis shows that the maximum principal stress angle is identical to the development direction of the cracks.%某沉管隧道分两层浇筑施工，在高度为2m的水平浇筑界面以上的侧墙出现了规则的竖向和斜向裂缝。为研究侧墙混凝土裂缝的成因，在沉管底板和侧墙内埋设振弦应变传感器，监测得知底板各监测点均产生收缩应变，侧墙水平方向从中部至端部实测收缩应变逐渐增大，竖向从下至上实测收缩应变逐渐增大。根据部分监测点的水平拉应力和剪应力，文章引入平面应力状态解析法，计算了最大主应力和最大主应力方向角，并与相应监测点附近裂缝发生情况进行对比，结果表明：根据监测数据计算的最大主应力的方向角与裂缝开展方向吻合。