Experimental study on multi-body coupling system for twin-barge hydraulic lifting shipwreck salvaging system

The twin-barge lifting method, applied in the overall salvaging scheme of ‘SEWOL’, is one of the main approaches for salvaging large-tonnage shipwrecks. A model experiment for the twin-barge lifting shipwreck salvaging system was conducted for three typical salvaging stages. Based on the experimental results, this study investigated the coupled dynamic response characteristics of the multi-body system consisting of the shipwreck and twin barges. The coupling effects between the multi-body system were discussed to understand the complex dynamic behaviour in twin-barge salvaging system, utilizing spectrum and statistical analysis. Additionally, this study considered the influence of the environment direction on the barge motion. It was revealed that the multi-body system exhibits significant shielding, which greatly affects the heave, roll, and pitch motions, particularly for beam and quarter seas. The maximum sling tension, including the case of single lifting sling broken, was also analysed to ensure safety under extreme conditions. Finally, it is advisable to perform salvage operations in head seas considering motion response amplitude, and to conduct the salvage in beam seas from the perspective of lifting slings safety. This study is of great significance for improving the safety of large-tonnage wreck salvage operations, promoting the development of research on multi-body system.