Study On Perturbation Method For Lateral Global Buckling Of Submarine Pipelines

With the rapid development of offshore oil recovery technology,submarine pipelines are widely used in oil and gas transportation worldwide.Bare submarine pipelines would easily trigger the lateral global buckling under the combined effect of high pressure and high temperature.It has attracted the attention of engineering and academia.In order to effectively consider the nonlinear characteristics of soil resistance,the nonlinear perturbation method is used to derive the analytical solution for lateral global buckling of submarine pipelines in this paper.Large deformation numerical simulation method and classical solution are used for verification.The main research content and innovative achievements are as follows:(1)The problem of lateral global buckling is solved by the nonlinear perturbation method.The perturbation method derives the analytical solution of lateral global buckling of ideal pipelines and pipelines with initial imperfections under the nonlinear constraint of soil resistance.The difference among solutions of perturbation method from first-order to fourth-order is analyzed.(2)The reliability of the perturbation method is verified by the proposed coupling method of PSI elements and the modified Riks algorithms.By compared with the classical solution,the reliability of the numerical simulation method is verified.Based on the nonlinear soil resistance model,large deformation numerical simulation of lateral buckling of pipelines are carried out,and then to compare with perturbation method.(3)Galerkin analytical solution of lateral global buckling under nonlinear soil resistance model is adopted to verify perturbation method.Galerkin analytical solution is a classical solution to the lateral global buckling.Its solving process is complicated and the amount of calculation is large,so it has not been widely used since it was put forward.Galerkin analytical solution verifies perturbation method furthermore.(4)The influence factors and regularity of lateral global buckling of pipelines are studied by perturbation method.The effects of unit pipeline weight and ratio of initial imperfection amplitude to wavelength on lateral global buckling shape and buckling axial force are analyzed.Results show that the increase of pipeline weight is beneficial to overcome the lateral global buckling.The initial imperfection amplitude of pipelines mainly affects the critical buckling axial force and initial temperature difference in the pre-buckling stage.