Numerical simulation of deepwater S-lay and J-lay pipeline using vector form intrinsic finite element method

S-lay and J-lay systems are progressively utilized for deepwater pipeline installation. The paper presents a simple and feasible model for the static and dynamic analysis of S-lay and J-lay pipelines. This mechanical model of the laying pipeline is established by the combination of the vector mechanics principle with the numerical technique based upon the vector form intrinsic finite element (VFIFE) method. The internal forces resulted from element deformations and node rotations as well as the external forces due to hydrodynamic loads and the boundary interactions are fully taken into account. The movement governing equation of pipeline particles is solved by the explicit central difference approach using program coding. Two numerical models of a 12-inch pipeline being laid to 1000 m water depth are created in order to illustrate in detail the modeling process of S-laying and Jlaying pipeline, respectively, and also verify the feasibility of the VFIFE model with a reasonable accuracy for deepwater pipeline installation. The effects of wave height and sloping seabed on the pipeline responses are identified and the noticeable differences of the pipeline behaviors between the S-lay and J-lay operation are observed. The results offer a significant reference for the installation design of the offshore pipeline.