Study On Lateral Buckling Control Measures Of Deep-sea Unburied Pipeline

Laying in the deep sea oil and gas pipelines,to withstand the role of high temperature and pressure,can easily lead to the overall pipe buckling.For deep sea,pipes are normally laid by unburied methods.Sleeper and buoyancy methods are used as a measure of lateral buckling in order to divide a "large" buckling into several "small" buckling.It is of great importance to study the overall buckling control measures of unburied pipes.In this paper,based on the ABAQUS software,using the pipe-soil friction contact model,the lateral buckling behavior of submarine pipelines with initial defects was analyzed by implicit dynamic algorithm.As well as the control effect of installing sleepers on the lateral buckling,analyzing the relationship between temperature,maximum stress and lateral deformation amplitude.The spring element was used to simulate the pipe-soil interaction and analyzed the influence of the parameters of the buoyancy unit on the buckling behavior.According to the current equivalent method of PIP,the numerical model of PIP with ITT31 contact unit is established.The parameters of ITT unit are analyzed,and analyzed the applicability of equivalent method in ABAQUS finite element simulation.The main research results are as follows:(1)The sleeper method induced the buckling of the pipeline in the preset position well,and the height of sleeper could effectively improve the effect of inducing total buckling and reduce the maximum stress,but the improvement effect was reduced with the increase of height.Rising sleeper surface roughness is not conducive to improving the induced effect,but conducive to control the lateral displacement amplitude.This conclusion has laid the foundation for practical application of the sleeper method.(2)The buckling of the pipe is very sensitive to the parameters of the buoyancy unit.The size of the buoyancy is more important than the buoyancy unit length.By analyzing the parameters of different buoyancy units,the influence mechanism of distributed buoyancy unit parameters on the overall buckling is revealed.(3)The initial defect wavelength and amplitude have an impact on the overall buckling of the pipe,but the amplitude has a greater impact on the overall buckling and the relative impact of the defect wavelength.Increasing the initial defect amplitude is equivalent to causing the pipe to buckle prematurely.(4)The reliable numerical model of double pipe was established and the influence of different outer pipe temperature on the overall buckling behavior of the pipe was obtained.