Experimental study on the hydrodynamic response of immersed tunnel segments during floating pouring under wave-current excitation

The technology of immersed tunnel floating pouring is susceptible to severe risks, including segment instability, excessive tension in mooring cables, and even structural overturning in complex hydrodynamic environments. Existing studies largely neglect the combined effects of progressive concrete pouring and dynamic marine loads, resulting in significant knowledge gaps. This study tested a 1:80 scale physical model in a wave-current flume to investigate the effects of wave parameters, current velocity, pouring stage, and mooring mode on the motion response and mooring cable forces of immersed tunnel segments during floating pouring. Results show that employing a "cross-mooring arrangement" method combined with a symmetric pouring scheme from the middle to both ends of the segment significantly enhances stability, reducing the sway motion amplitude by up to 51.4%. Compared to the initial pouring stage (Stage 1), the sway, heave, and roll amplitudes in the final stage (Stage 5) increase by 36.3%, 57.7%, and 43.9%, respectively. Additionally, segment stability is found to sharply decline under extreme conditions of high wave height and long period, with corresponding peak values reached in mooring cable tension. These findings provide valuable insights into the stability design for immersed tunnel floating pouring process.