Parametric Study on Mooring System Design of Submerged Floating Tunnel under Extreme Wave and Seismic Excitation

• Published in: Journal of marine science and engineering Vol. 11; no. 12; p. 2357
• Main Authors: Chung, Woo Chul, Jin, Chungkuk, Kim, MooHyun, Kim, Sewon
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.12.2023
• Subjects: Boundary conditions; Construction; Depth; Design; Design parameters; Dynamic response; earthquake; Earthquake resistance; Earthquakes; Elasticity; Environmental conditions; Extreme waves; Floating; Mooring; mooring interval; mooring system design; Mooring systems; Seismic activity; Seismic engineering; Seismic response; Sensitivity analysis; Simulation; Simulation models; Structural integrity; submerged depth; submerged floating tunnel (SFT); Systems design; Tunnels; South Korea
• ISSN: 2077-1312; 2077-1312
• DOI: 10.3390/jmse11122357

This study proposes a mooring design strategy for a submerged floating tunnel (SFT) subject to extreme waves and earthquakes. Several critical design parameters, such as submerged depth and mooring station interval, are taken into account. As a target structure, a 700 m long SFT system with permanent stations at both ends, representing the fixed–fixed-end boundary condition, is established. To consider coupled dynamics between the tunnel and the mooring system with structural elasticity, an efficient time-domain simulation model is established. Three combinations of environmental conditions are considered: extreme wave only, extreme earthquake only, and both extreme earthquake and operating wave. First, to check the submerged-depth effect on the dynamic response of the SFT system, including mooring tension, two different submerged-depth (deep and shallow) types are simulated and analyzed. It is confirmed that the deep submerged-depth model (A-type) has an advantage under extreme wave conditions, whereas the shallow submerged-depth model (B-type) is equipped with better resistance when subject to an earthquake. Thus, the compromise submerged-depth model (C-type) is newly devised to enhance structural integrity under various environmental circumstances. Furthermore, a mooring station interval sensitivity test with the C-type is performed and demonstrates the integrity of the C-type.