Dynamic response characteristics of an entire long span submerged floating tunnel tube under wave and current loads

Abstract

This study performs a numerical investigation of the dynamic response characteristics of a three-dimensional, full-scale submerged floating tunnel (SFT) tube using finite element software coupled with hydrodynamic analysis subroutines, under regular-wave and combined wave-current excitation. The tube's motion responses - including displacements, response frequencies, and motion trajectories - are systematically analyzed. Results indicate that under pure wave excitation, displacement amplitude is positively correlated with wave height and negatively correlated with wave incidence angle, exhibiting a non-monotonic dependence on wave period. The response is predominantly single-frequency, matching the wave frequency. Under combined wave-current loading, dynamic responses are jointly governed by current velocity, wave height, and wave period. Sway and torsional displacements strongly depend on all three parameters, whereas heave displacement is primarily associated with wave height and shows weak sensitivity to current velocity and wave period. The response exhibits multi-frequency characteristics, with a secondary component at twice the fundamental frequency.