Abstract: 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. 

Key words: immersed tunnel, assembled steel bulkhead, waterstop rubber strip, stress, deformation, installation and dismantling procedure