Non-linear Finite Element Simulations Of Submarine Pipeline During Installation From Laybarge

During the pipe-laying operation with a lay-barge, one end of the pipeline is put on the seafloor, the other on the lay-barge, and the suspended part of the pipeline is very long. In case of the pipeline overstressing, the mechanics properties of the pipeline should be analyzed quickly and accurately according to the marine environment, so that the reasonable working parameters of the lay-barge could be determined. In fact, the suspended pipeline has the nonlinear properties in geometry, it's length and the force of the touch down point are unknown during laying operations, so that the question is difficult to be solved. Much methods of the pipeline analysis have been put forward during the past thirty years, but almost all of them are limited in the analysis accuracy, speed and common use. Little study on the beach pipeline-laying has been done till now, and there is no any analysis software of pipeline suitable for engineering in our country.To meet the requirements of pipelines laying in our country, it is urgent to solved the problems of mechanics properties of the pipelines. This paper is closely combined with the key project of "Pipeline and Cable laying on Beach", design and manufacturing of the first lay-barge in our country sponsored by The China National Petroleum Company. The mechanic properties of the pipeline and related techniques are studied deeply in this paper.The differential equations are established according to the non-linear finite element theory and pipeline element force balance, The differential equations are deduced to pipeline element stiffness matrix and then composing total stiffness matrix by using the finite element method. The problem of the non-linear coupled equations is tackled by means of over-relaxation iterative calculation approach. The method not only considered the aspect of non-linearity, elasticity and large deformation of the pipeline but fitted numerical calculation with computer. This method can be used to analyze the static and dynamic problems of pipelines under different conditions, and treat with complex loads and boundaries. The results of the relationship among calculating speed, accuracy and common use are very well by using this method.