Abstract: To investigate the relationship between wave parameters and the motion law of tube, as well as the tension of mooring cables, in the sinking system during the construction process of the submerged floating tunnel(SFT), the wave-induced characteristics of a largescale elliptical SFT tube under regular wave action are analyzed using the numerical simulation methods based on the ANSYSAQWA software. The feasibility of the proposed numerical method is validated using a scale-model experiment of SFT tube, and the time-history curves, the response-amplitude-operator(RAO) curves, and cable force distribution patterns of the large-scale elliptical SFT tube in wave environment are examined. The variation relationships between the time/frequency-domain motion characteristics of the sinking system and wave parameters including the period, wave height, incidence angle, as well as the sinking depth and buoyancy-weight-ratio(BWR) of the tube, are obtained. The results reveal the following: (1) Both the tube displacements and the cable forces increase significantly as the wave height and period increase, when they grow to a certain degree, the tube displacements exhibit nonlinear characteristics and the anchor cables show slack. (2) During the process of increasing the incident angle, the distribution pattern of the heave RAO curve is basically consistent, with an increase in roll value and a decrease in pitch value. (3) The sway RAO curve pattern is consistent at different sinking depths. The heave RAO curve is very sensitive to the sinking depth, and as it increases, the heave value decreases. When the sinking depth is greater, the roll value is smaller. (4) When the BWR of tube decreases, the amplitude of the transverse displacement of tube decreases and becomes periodic or quasi-periodic motion. The cable tension is greater than zero, the slack phenomenon disappears, and the time history of the cable tension shows a quasiperiodic pattern.

Key words: submerged floating tunnel, sinking, characteristics of wave-induced motion, numerical simulation, response-amplitude-operator curves