Research On The Pipe Mechanical Characteristics Of Deep-water Pipe-laying Vessel

During the pipe-laying operation with a lay-barge, one end of the pipeline is put on the sea-bed, the other on the lay-barge, and the suspended part of the pipe line is very long. In case of the pipe line over stressing, the mechanics properties of the pipe line should be analyzed quickly and accurately according to the marine environment, so that the reasonable working parameters of the lay-barge could be fixed. In fact, the suspended pipeline has the nonlinear properties in geometry, its 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 universality. 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.Previous studies always focus on a particular laying way, The key to the study is the establishment of methods of pipeline differential equations, and then discussed the method. In this paper, several kinds of analysis methods of the sea pipeline elastic deformation while lay down in deepwater are compared Make use of nonlinear elasticity theory to set up the pipe mode, then use non-linear finite element method to obtain the numerical solution. This method not only takes full account of pipeline's elasticity, non-linear and geometry big deformation problem, but also uses computer language carries on the numerical calculus easily. Using this method can handle complex forces and boundary conditions, and handle the relationship well between speed, accuracy and universality which exist in the method of analysis of the marine pipeline.In order to solve the problem which exists between the theoretical analysis and the project application, this thesis based on the previous studies of static and dynamic analysis about the pipeline-laying, and then discussed the method of mathematical model establishment and solution while the lay-barge works in deep water. Based on this, I use the ANSYS software to set up the finite element models of various types of pipes' laying operation and got the numerical solution. Finally, some suggestions referring to the pipe laying design obtained after considering the reality of construction, and studying the factors such as the stinger shape, the size of entry angle, the laying of the way ocean current in the impact of changes in the pipeline, meanwhile, the influence of pipeline stress on the Ship floating state is calculated.