Study On Dynamic Response Of The Pipe-lay And Mooring System Considering The Pipeline

There are two main methods of laying marine pipe: J-lay and S-lay. J-lay is widelyused in deep sea as it does not require stinger and its laying stress is much smaller. Thispaper analyzes the J-Lay pipe lay and the Mooring system using the coupling analysismethod, and the dynamic response of vessel, pipes and mooring system been obtained. Themain research contents and results are summarized as follows:1. Research on the hydrodynamic characteristics of the vessel. Based on the potentialflow theory, this paper take a numerical analysis on floating platform, and get the addedmass, damping and RAO of the vessel.2. Research on the hydrodynamic performance of the vessel and mooring system.Motion performance of the vessel and tension of the lines are simulated with differentincoming wave angles.3. Research on the hydrodynamic performance of the vessel and mooring system whenpipe-laying. Mainly research two conditions to analyze the impact of vessel movement andthe tension of the lines. One is considering different kinds of pipes, the other consideringdifferent incident waves.4. Research on the strength of the pipeline when laying the pipe. Different pre-tensionand different incident waves when pipe-laying are considered to discuss the comparison ofthe pipeline strength.Through researching and analysis, the main conclusions of this paper are obtained asfollows:1. With the wave direction angles increasing, the surge movement becomes smaller andthe sway movement is just the opposite when the vessel subjected to the incident wave withthe angle of0°to90°. As the angle reached90°, the tension of the mooring liner gets themaximum.2. There is a significant change of sway、surge and yaw when considering the impact ofthe pipeline; the pipeline has a significant influence on the mooring system. The tension oftwo lines become slightly larger and other six lines are significantly smaller; there is asignificant relationship between wet weight of the pipeline and the pre-tension of thepipeline, the greater Wet weight is, the larger the tension is;then the impact of vessel motionis larger. 3. The axial stress of pipeline gets larger as the pre-tension increases, and the bendingstress and the combine stress are just the opposite. Bending stress plays a leading role intotal stress of pipeline. With the wave direction angles increasing, the tension and bendingmoment become larger when the vessel subjected to the incident wave with the angle of0°to90°; The stress of pipeline is been influenced directly by the heave motion.