Simulation of TDP Dynamics during S-laying of Subsea Pipelines
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- Institutt for marin teknikk 
During the past one and a half decade, pipeline has been proven to the most economical means of large scale overland transportation for crude oil, natural gas and other products. At the same time, more and more problems are encountered. A lot of effort has been put to gain more knowledge about pipeline installation, operation and so on. During installation of subsea pipeline, the penetration of the pipe prior to operation has a tendency of being larger than the predicted values. This may have a great influence on the intervention work and cost impact. It is therefore of interest to investigate whether this behavior can be explained by the dynamics at the touch down point (TDP) induced by 1st order motions from waves. This thesis work therefore focus on dynamic simulation of pipelines using the computer code SIMLA and put special emphasis on investigating the work done by the pipe onto the soil at TDP as the installation process goes on. For this purpose, a dynamic analysis model for a 32 inch pipeline at 200-300 m water depth is established with SIMLA input code. Both static and dynamic analyses are performed. A comparable very long time analysis time is applied in order to get stable results. The influence of various parameters viz. wave height, wave period and wave direction are investigated in this thesis. The TDP dynamics as a function of sea state is investigated with concentration on the dynamic pipe-soil interaction force and displacement as a function of time.