Study On Numerical Simulation Of Lateral Buckling Of Deep-sea Unburied Pipeline

To meet the working condition of deep sea oil and gas transportation,the temperature of the submarine oil and gas pipeline is over 100?,and it has been widely used under high temperature and high pressure environment.However,pipeline that works under high temperature and high pressure may occur in global buckling,which leads to local buckling,strength failure and consequent fatigue failure,will affect the normal operation of the submarine oil and gas pipeline.So it is of important meaning to study the global buckling characteristics of submarine pipelines.In this paper,the first order mode of global buckling of the pipeline is deduced based on the Hobbs' s theory of buckling mode,and then global buckling behavior of the submarine pipeline with initial defects is analyzed by using ABAQUS software.In the end,given the stress and deformation of the pipeline,the influence of different seabed topography on the stress and displacement distribution of the pipeline is studied by comparing the two typical models.The main conclusions are as follows:(1)Theoretical research of the first-order of global lateral buckling has been done.Formulations of axial force and deformation are studied.They only depend on the parameters of pipeline.(2)With the increase of temperature,the pipeline has the deformation at the initial defect.When the lateral buckling displacement increases to a certain value,the displacement appears in the opposite direction.Because both ends of the pipe are fixed,the axial force of the pipe ends is the largest,and the axis force of the pipeline decreases linearly from the ends to the midpoint.(3)The stress and displacement of the pipeline reaches the maximum at the midpoint of the pipeline.So the midpoint of the pipeline is the most insecure.(4)The seabed induced along the pipeline has a great influence on the distribution of the axial force of pipeline.The larger the inclined angle is,the bigger the difference between the two sides of the pipeline will be.The maximum stress of the inclined pipe is at the initial defect of the pipeline.The lateral deformation of the inclined pipe is larger than that of horizontal pipe,and the maximum lateral buckling displacement occurs at the initial defect of the pipeline.(5)The lateral buckling displacement,stress distribution and axial force distribution of pipeline are greatly affected by the seabed induced along the the vertical direction of pipe.The larger the the inclined angle is,the larger the displacement of the pipeline will be.The maximum displacement and maximum stress occurred at the initial defect of the pipe or the reverse bend.