Fluid-structure interaction of submerged floating tunnel in wave field

Abstract

The aspect ratio of submerged floating tunnel (SFT), i.e. the ratio of length to diameter, is usually as large as 102 to 103, which means the behavior of SFT would like a slender cylinder restrained by tethers. Although SFT is usually placed under the water surface at a certain depth, surface wave has important influence on its dynamic response due to the slenderness. This paper performs analyses on the fluid-structure interaction of SFT in wave field. Potential fluid theory is adopted to describe the wave field. Boundary element method is used to solve the interaction between SFT and surface wave. Wave potential is divided into three parts, including incident wave potential, diffraction wave potential and radiation wave potential. SFT is discretized into finite elements and its dynamic response is finally solved in frequency domain. As a case study, the values of design parameters for SFT prototype in Qiandao Lake are adopted. Two different tunnel end connectors are used to compare the distributions of tunnel deflections, axial membrane forces at the tube segment connectors and tunnel end connectors.