STUDY ON NUMERICAL SIMULATION OF JACKET LAUNCH PROGRESS

Jacket type structures are widely used in shallow waters. The size of a jacket is determined by the dimensions of the deck and piles, as well as the environment loads. The jackets are usually transported with barges to the operation water after they have been fabricated in the shipyard, then the jackets slip into the water. Launch operation is the most hazardous stage during the installation of a jacket. The main purpose of this study is to evaluate the physical modeling test results for the launch, and compared to those of numerical simulation. It is found that there are some differences between the numerical simulations and physical model tests. The scale effect cannot be ignored in the prediction of the jacket launching process. The model test is based on the Froude similarity law, and the effect of Reynolds number is neglected. The drag coefficient depending on the Reynolds number plays a crucial role in determining the launch process. With different Reynolds number, the structure has different hydrodynamic force that results to different pitch angle, heave, launch time, acceleration and so on. Thus, a scale effect emerges when we convert the results of a wave basin model test to the prototype scale. This study also includes a sensitivity analysis about some key parameters in the launch process, such as initial barge trim and draft, frictions between barge and jacket.