ABSTRACT
Deflection of the tube of submerged floating tunnel (SFT) under environmental loading such as current, long crest wave or even sea density variation as well as its vibration characteristic are of great interest to engineering researchers. In this paper, the simplified two-dimensional SFT mathematical models are expressed by a set of partial differential equations, including four partial differential equations and four boundary conditions, totally 16 combinations. Each represents a type of SFT with a specific way by which the tube connects to the shores. They are SFT with or without cables, SFT with or without axial compression or tension, SFT with two fixed or pinned ends and SFT with only one pinned or fixed end. And the last one stands for the constructional stage. The analytical solutions to the simplified two-dimensional SFT models are obtained by using the method of variables separation. And these solutions apply to the tether type SFT in both operational stage and constructional stage, where the cable mass must be negligibly small compared to the tube mass, tube section must be constant along its length and the cable is idealized by continuous springs. Finally, the examples of application are given. The research results provide a theoretical reference for further study and construction of the SFT.
The SFT was proposed more than 150 years ago. Norway, Turkey, Italy, Japan and China have all studied it at different times, but it has never been built [1]. The Hong Kong-Zhuhai-Macau bridge islandtunnel project has built the longest highway immersed tube tunnel in the world, overcoming a series of difficult problems such as the installation of complex sea conditions, deep burial, siltation, abnormal waves and plume. Today, immersed tube tunnel technology has been developed into the third generation, and the next breakthrough should be the realization of SFT technology [2]. After the completion of the Hong Kong-Zhuhai-Macau bridge island-tunnel project in 2018, China Communications Construction Company Limited has set up the Joint research group of suspended Tunnel Engineering Technology with 11 research directions [3], and the model of education, research and production has also been established. Participating organizations include Northwestern Polytechnical University, Dalian University of Technology, Dutch TEC company, Delft University of Technology, etc. The research team of structure and design method was established in 2019. And this paper is one of the research achievements of the project team.
