Abstract
Submerged floating tunnels (SFTs) are innovative structural solutions to waterway crossings and are more economical compared to the conventional structures such as cable-supported bridges, underground tunnels or immersed tunnels. The dynamic behaviors of SFT under real train loads is the primary design requirement of an SFT, However, it is not investigated using realistic train models. In this study, the China-star high-speed train is used to evaluate the dynamic displacements, internal forces and cable tensions of SFT. The tunnel is modeled by FEM, the cables are modeled by elastic catenary cables, and ocean waves and currents are modeled by Airy’s wave theory. The SFT displacements, bending moments and cable tensions were significantly influenced by moving trains. The SFT experienced extreme vertical displacements and there was a large drop in the minimum cable tensions. The mooring cables were slacked both by magnitudes and speed of the moving trains, which should be avoided for the safety of SFT. This study recommends the additional buoyancies for the stability of SFT subjected to high speed trains.
Highlights
Connecting the opposite shores of lake, fjord, river, and sea strait through a structure, has always been a challenging task for the engineers
The dynamic responses of submerged floating tunnel (SFT) are evaluated for the China-star high-speed train, the design speed of this train is 270 km/hr
To evaluate the effect of moving trainloads on the responses of SFT, three load combinations are defined as: (1) Load combination 1 (LC1): in this load combination, the dynamic responses of SFT are evaluated under moving trainloads
Summary
Connecting the opposite shores of lake, fjord, river, and sea strait through a structure, has always been a challenging task for the engineers. A procedure for the nonlinear dynamic analysis of SFT considering 3D multi-support seismic excitations and nonlinear drag forces due to steady current and wind waves was presented by Di Pilato et al [6]. The dynamic problem of SFT is formulated, modeling the tunnel as FEM and mooring cables as catenary elements. The dynamic responses of SFT under waves, ground motions and China-star high-speed trainloads are evaluated, and some useful conclusions are drawn from the numerical simulations. Moment of inertia Length of tunnel Elastic modulus Diameter of cable Moment of inertia Cable density Wave height (H) Time period (T) Surface current velocity ( Uc) Depth of water (h) Distance of SFT from free surface (h1) Density of water (ρw) Drag coefficient (CD) Inertia coefficient [35]
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