Dynamics of a moored submerged floating tunnel under tsunami waves

Abstract

This paper investigates the dynamic behavior of a moored submerged floating tunnel (SFT) under tsunami-like waves. A hydro-elastic numerical study is conducted with the time-domain dynamics simulation model that considers structural deformability through 1D line elements. Tsunami-like waves (solitary wave, 2011 Tohoku-tsunami, and 2005 Indian-Ocean-tsunami) are applied to the numerically modeled dynamic system to demonstrate the effects of tsunami wave profiles on the hydro-elastic behavior of the SFT and mooring-line tensions. After setting the numerical model, systematic sensitivity tests are conducted concerning various design parameters, such as drag coefficient, wave height, buoyancy-weight ratio, and water depth. The results show that SFT dynamics and mooring tensions can significantly depend on those design parameters. The SFT system is generally more vulnerable to shorter-duration and higher-elevation tsunamis due to greatly enlarged SFT transient motions and mooring snap loadings—a shorter-duration solitary wave results in 2.5 times higher maximum lateral SFT motions than longer-duration combined waves. Also, a three times larger full lateral movement is observed when tsunami elevation is doubled in combined waves. The results highlight the roles of those design factors and tsunami patterns so that they can be applied to the design of future SFTs in tsunami-prone regions.