Abstract: Su′ai shield tunnel in Shantou is the first extralong and super largediameter subsea shield tunnel located in 8degree seismic intensity area in China. In this paper, the design process of the project is reviewed. First, every special research completed in phases of engineering feasibility study, preliminary design and construction drawing design of Su′ai Tunnel are presented, and experience is summarized. Second, the main contents of route comparison and selection, construction method comparison and seismic design are introduced, and the thinking of design consideration of various schemes, specific methods of seismic design and specific values of waterproof standard, etc. are provided. Finally, the experience of the design of this project is summarized, and some advices are proposed to provide a useful reference for the design of underwater shield tunnel in high seismic intensity area.

Key words: subsea shield tunnel, 8degree seismic intensity area, tunnel design, route comparison, construction method selection, seismic resistance design, waterproof standard