Abstract: The authors discuss the feasibility of immersed-tube tunnels in ultra-deep (over 100 m) water areas such as Taiwan Strait, and make a investigation on global immersed-tube tunnels such as the Hong Kong-Zhuhai-Macao bridge and the Shenzhen-Zhongshan link. Based on three major technical challenges of immersed tube tunnels, i.e., element joint, foundation, element floating and installation, the adaptability of element structure, joint sealing system, foundation, and floating and installation ship machinery equipment are discussed from the perspectives of scheme design and construction technology. The results demonstrate that the immersed-tube tunnels are feasible for crossing Taiwan Strait by redesigning GINA waterstops, developing novel equipment, measurement and control systems, and sinking systems. 

Key words: Taiwan Strait channel, ultra-deep immersed-tube tunnel, joint waterproofing, foundation treatment, element sinking and installation