Theoretical framework of life cycle design of the submerged floating tunnel

The life cycle design of the submerged floating tunnel(SFT) is to consider the safety, applicability, durability, service life requirements, environmental and social impact etc various factors of the structure during the whole process of design, construction, operation, maintenance, repair, failure and dismantling, give corresponding optimization and cost prediction and control to achieve optimal decision-making. In this paper, the method of "target system.research content.research method" is used to study and establish the theoretical framework of whole life cycle design of the SFT. The research target system mainly includes structural risk control goal, structural reliability goal, economic optimization goal, time optimization goal, social environmental goal, user satisfaction goal and regional sustainable development goal. According to the corresponding target system, the content, influencing factors or index system of relevant research are proposed. The research results show that the service life and risk control of the SFT are related to the section type, the strength and deterioration of each material, the load type, the strength of the action forces, the magnitude and position of the change, the safety of the structural design, the construction quality, and the maintenance and repair measures. At the same time, they also affect the overall cost of the structure and the maintenance cost of SFT in the later period. Therefore, design and decision makers should conduct detailed research and analysis of influencing factors to make more scientific and reasonable decision and choice.