Effects of Submergence Depth of Submerged Floating Tunnel on Global Behaviors under Waves and Earthquakes

A submerged floating tunnel is an innovative structure designed for deep-water, long-distance crossing. In this study, two conceptual designs with respect to submergence depth of the tunnel were suggested, and feasibility of them was analyzed under harsh waves and earthquakes. Slender tunnel sections and mooring lines were modeled by the lumped-mass-based line model. The Morison equation was utilized for wave-load estimations. Dynamic responses of the tunnel and mooring tensions were analyzed to evaluate the characteristics of both designs. Larger responses are observed from the case of same submergence depth of the tunnel than variable one under wave excitations. However, while both cases have similar dynamic responses under seismic excitations, same submergence depth of the tunnel contributes to smaller mooring tensions.