Advanced Developments in Steel and RC Immersed Tunnels Sakaeda Hideki, Ozgur Ozturk, Tsang Chor Kin AECOM, Hong Kong SAR Online published on 20 April, 2019. Abstract By the help of recent advanced technologies and innovative solutions in steel and reinforced concrete immersed tunnels, very deep and very long sea crossings under challenging ground and environmental conditions becomes feasible and competitive. Sandwich or hybrid immersed tunnels are popular in Japan where both internal and external surfaces are constructed by structural steel plates. Steel diaphragm plates and shear connectors are used between internal and external surfaces, fi lled with non-shrinkage self-compacting concrete, eliminating the necessity of reinforcement bars. On the other hand, the mega highway immersed tunnel project, Hong Kong-Zhuhai-Macao Bridge Link (HZMB) is currently under construction as reinforced concrete immersed tunnel where segmental full-face casting technique has been applied. It is the fi rst very long immersed tunnel project with two artifi cial islands in the open sea in China, connecting Hong Kong SAR, Zhuhai (PRC) and Macao SAR once completed. High quality concrete and full-face segmental casting minimized cracking risk. In addition, submersible fl oating tunnels are also being considered to be built in the future which may extend the immersed tunnelling technology one more step further. This paper discusses about the recent advancement of immersed tunnel construction technologies by giving examples from the recent projects. Top Keywords Reinforced Concrete, Steel, Hybrid, Immersed. Top |