Study On Lateral Buckling In Low Order Mode Of Submarine Pipelines

With the rapid development of the world marine petroleum industry, submarine pipelines have been widely used in the offshore oil and gas exploitation. In order to reduce the difficulty of transportation, oil and gas must be transported in the condition of high pressure and temperature, which always leads to the global buckling of submarine pipelines under temperature stress. Therefore, it is of practical engineering significance and high theoretical value to reveal the mechanism of pipeline buckling and develop the analysis approaches under thermal load. This paper mainly applies a method combined with theoretical deduction and numerical simulation to study the mechanism and analysis approaches of pipelines’global lateral buckling. The main research contents are as follows:Submarine pipelines’global lateral buckling is classified in ideal conditions. Mathematical model and mechanical model are introduced respectively for different category of pipeline. Afterwards the theory knowledge including theoretical mechanics, material mechanics, structural mechanics and advanced mathematics is used to get the corresponding analytical solutions for model curve shape. Based on the results above, further analysis on linkage between and among coefficient of friction between pipelines and soils, temperature, buckling strength and buckling amplitude is carried out. This paper introduces the improved Riks method to establish models of temperature field and temperature flow,properly modeling contact relationship between submarine pipeline and soil simultaneously, which are ultimately applied to finite element simulation for post-buckling behaviors of submarine pipeline withstanding temperature stress.The study approves that the coefficient of friction between pipelines and soils has a great influence to global lateral buckling of submarine pipeline. In considering low-level buckling mode merely, the second global lateral buckling mode of submarine pipeline occurs more easily. When initial defect is small, the curve of arch magnitude versus temperature has obvious instability, which appears to have a gradual change when initial defect is large. With the pipelines’initial imperfection increases, the global lateral buckling of pipelines’critical temperature decreases; In considering temperature flow, the global lateral buckling of pipelines’critical temperature and buckling stress are little smaller.