The Study On Displacement Constraint Technique Of Submarine Pipeline In Deep-Sea

Submarine pipeline is the oil and gas transportation tool,which connects wells and platform,platform and land transportation facilities.It has the advantages of safety,stability,economy,large conveying capacity and so on.And it is an important part of marine oil and gas transportation system.This paper focuses on solving specific problems in real submarine pipeline projects,using mathematical models and finite element analyses,based on the stability of submarine pipeline,studies displacement constraint technique of submarine pipeline in deep-sea and obtains practical and reliable quantitative conclusions.Through finite element software ABAQUS,a seabed soil-pipe coupling system model was established in operation condition and out of service.Through balancing the seabed soil in-situ stress,analyzing self-loading of pipeline,setting seabed soil-pipe contact,studying internal pressure of pipeline,researching Pipeline buckling,displacement distribution and stress distribution can be calculated in operation condition and out of service.The analysis results show,large deformation caused by temperature difference and pressure difference is the most important reason of failure situations of pipeline.At the same time,by comparing the simulation research,we can conclude that The parameters of the seabed soil,such as young's modulus,poisson's ration,cohesive force,ect.,makes a difference on the Buckling of pipe differing in degree.The size of the effect depends on stiffness of the seabed soil and lateral soil resistance acting on the pipeline.Based on the above study,this paper studies the commonly used displacement constraint technique of submarine pipeline by modeling analysis,including increasing the coefficient of friction between the pipeline and soil,increasing negative buoyancy of pipeline,burying part of submarine pipeline.Calculation results show that the three kinds of displacement constraint technique of submarine pipeline all limit the displacement of submarine pipeline which caused by lateral buckling.The size of displacement constraint depends on the passive earth pressure of soil and the tangential friction force between pipeline and soil.The bigger the passive earth pressure of soil and the tangential friction force between pipeline andsoil,the smaller displacement of submarine pipeline caused by lateral buckling,the greater insurance the running stability and security of submarine pipeline.