襄阳汉江沉管隧道新型装配式钢端封门研究及应用

Research and Application of Assembled Steel Bulkhead for Hanjiang Immersed Tunnel in Xiangyang,China

在安装与拆除传统现浇混凝土结构端封门与焊接式钢端封门时,作业效率低下,且会产生废气。为解决该问题,基于襄阳汉江沉管隧道项目,研发新型装配式钢端封门,以实现沉管隧道端封门的循环利用。在所研发的新型装配式钢端封门接缝内安装三元乙丙橡胶条,通过柔性橡胶条的受压变形,实现接缝的止水功能,并通过室内试验对止水橡胶条的水密性及压缩变形特性开展研究;然后,进行新型装配式钢端封门的构造与安拆工艺设计,并对其受力与变形特性开展数值仿真与现场监测。研究结果表明:(1)拼装错位量及接缝宽度为关键指标,当端封门子块与沉管结构间的接缝宽度小于15 mm时,可保证40 m水深下接缝不漏水;当相邻端封门子块间的接缝水平错位量小于40 mm及接缝宽度小于15 mm时,可保证30 m水深下接缝不漏水。(2)研发的具有横移行走、纠偏、升降、仰角调节等功能的安装台车,可快速精准地实现端封门子块的空间姿态调整。(3)随着沉管单元下沉深度增加,端封门H型钢部件的弯曲应力与弯曲变形呈线性增大趋势,但均未超过设计值。

When installing and dismantling traditional cast-in-place concrete bulkheads and welded steel bulkheads,the work efficiency is low,and gas pollution is produced.To address these issues,a case study is conducted on the Hanjiang immersed tunnel project in Xiangyang,China,and a novel assembled bulkhead is developed to realize the recycling of bulkhead doors of immersed tunnels.Ethylene-propylene-diene monomer rubber strips are installed inside joints between steel bulkhead fragments,and the water-stop function can be realized through the compression deformation of flexible rubber strips.Via indoor tests,the watertightness and compressive stress-strain characteristics of water-stop rubber strips are examined.The structure and installation process of the newly assembled bulkhead are designed,and the on-site monitoring and numerical simulation of its stress and deformation characteristics are performed.The results indicate the following:(1)The maximum horizontal misplacement between the adjacent steel bulkhead and joint width are the key indicators of installation.When the opening between the bulkhead fragment and immersed tunnel element is less than 15 mm,the joint does not leak under a water depth of 40 m.When the horizontal misplacement of the joint between adjacent bulkhead fragments is less than 40 mm and the opening is less than 15 mm,the joint does not leak under a water depth of 30 m.(2)The installation trolley with the functions of traverse walking,deviation correction,lifting,and elevation adjustment is developed to realize space attitude adjustment of the bulkhead fragments quickly.(3)With an increase in the sinking depth of tunnel elements,the bending stress and deformation of the I-shaped steel parts of the bulkhead increase linearly but do not exceed the design values.