Experimental study on 3D hydroelastic response of entire long span submerged floating tunnel with catenary-mooring constraint and perpendicular regular waves action

Clarifying the hydroelastic dynamic response of submerged floating tunnel (SFT) is an important prerequisite for its safety design. Currently, most of the research focuses on theoretical analysis and numerical simulation, and lack of relevant 3D model tests. In this series of studies, 3D entire long span experiments were carried out to systematically study the hydroelastic response mechanism of the SFT. The practical end constraint, the elastic deformation along the tunnel and the coupling effect between the tube and the mooring system was entirely experimentally simulated. Taking the catenary as the mooring system and perpendicular regular waves action, this paper analyzes the 3D hydroelastic response characteristics of the submerged floating tunnel under different wave periods and end pretension conditions, the tube displacement, acceleration and mooring tension along the tunnel were carefully measured. The test results show that the wave period has a significant effect on the displacement and acceleration of the tube, especially when the wave period is close to the structure natural period, the amplitude reaches the maximum, and the displacement and acceleration of the tube reach the maximum at the mid-span. Both horizontal and vertical displacement and acceleration increase first and then decrease with increasing the relative frequency f/f_N and KC number. With the increase of the end pretension, the maximum displacement or acceleration amplitude decreases, and the response peaks shift to the direction of low KC number. After applying the end pretension, the horizontal displacement and acceleration amplitude of the tube decrease, but the vertical displacement and acceleration amplitude increase. Increasing the end pretension will increase the mooring tension, and the tension amplitude of the waveward side is always higher than that of the leeward side.