Analysis of wave force induced dynamic response of submerged floating tunnel

Submerged floating tunnel (SFT) is an innovative underwater structure for crossing long straits, which withstands the effects of water wave and current throughout its lifecycle. This paper proposes a theoretical approach to investigate the nonlinear dynamic response of the SFT tube-cable system under combined parametric excitation and hydrodynamic forcing excitations (i.e., wave and vortex-induced loading). Firstly, the governing equations of the SFT system considering the coupled degrees of freedom in the tube and cable are established based on the Hamilton principle and are solved numerically. Then, several representative cases are analyzed to reveal the dynamic characteristics of the SFT. Finally, some key parameters are discussed, such as the wave and current conditions and the structural parameters. The results show that when the flow velocity reaches a certain value, the vortex-induced vibration (VIV) of the anchor-cables will excite a strong resonance in the structure. The displacement amplitude of the SFT increases with the increase of the wave height. Gravity-buoyance ratio (GBR) of the tube and the inclined mooring angle (IMA) of the cables jointly determine the natural vibration frequency of the SFT. The influence of the wave force on the tube is limited when the installation depth of SFT is more than 40 m.

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Dynamic Response of a Porous Seabed and an Offshore Pile to Linear Water Waves

Volume 4: Ocean Engineering; Offshore Renewable Energy ◽

10.1115/omae2008-57814 ◽

2008 ◽

Cited By ~ 1

Author(s):

Jian-Fei Lu ◽

Dong-Sheng Jeng

Keyword(s):

Dynamic Response ◽

Water Waves ◽

Coupled Model ◽

Expansion Method ◽

Wave Theory ◽

Horizontal Displacement ◽

Element Model ◽

Wave Force ◽

Acoustic Medium ◽

Linear Wave

In this study, a coupled model is proposed to investigate dynamic response of a porous seabed and an offshore pile to ocean wave loadings. Both the offshore pile and the porous seabed are treated as a saturated poro-elastic medium, while the seawater is considered as a conventional acoustic medium. The coupled boundary element model is established by the continuity conditions along the interfaces between the three media. In the system, wave force is considered as an external load and it is evaluated via the wave function expansion method in the context of a linear wave theory. Numerical results show that the increase of the modulus ratio between the pile and the seabed can reduce the horizontal displacement of the pile and the pore pressures of the seabed around the pile. Furthermore, the maximum pore pressure of the seabed usually occurs at the upper part of the seabed around the pile.

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Dynamic Response Comparison of Mono and Dual Submerged Floating Tunnels

Volume 6B: Ocean Engineering ◽

10.1115/omae2020-18882 ◽

2020 ◽

Author(s):

Woo Chul Chung ◽

Chungkuk Jin ◽

MooHyun Kim

Keyword(s):

Dynamic Response ◽

Dynamic Responses ◽

Hydrodynamic Load ◽

Extreme Wave ◽

Lumped Mass ◽

Mooring Lines ◽

Drag Forces ◽

Different Types ◽

Submerged Floating Tunnel ◽

Fully Coupled

Abstract Submerged floating tunnel (SFT) concept has been studied by many researchers as an alternative of conventional or floating bridges, especially in the fjord or as a connection between island and land. One of the major challenges is large dynamic responses under extreme wave and earthquake excitations. In this regard, two different types of SFT, which are mono and dual SFTs, are suggested in this study, and the global performance of them is compared through tunnel-mooring fully-coupled time-domain numerical simulations. The tunnel and mooring lines are modeled by the lumped-mass-based line model. The Morison equation is utilized for hydrodynamic load estimations of the tunnel and mooring lines at their instantaneous positions. To check dynamic response of SFT under operating condition, 10-yr waves with the current are considered as an environmental condition. Dynamic responses, mooring tensions, and inertial and drag forces are systematically compared.

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