【作者】 李彪；

【导师】 刘润；

【作者基本信息】 天津大学 ， 岩土工程， 2012， 硕士

【摘要】 随着世界海洋石油工业的迅猛发展,海底管线在海洋石油、天然气开采中得到了广泛的应用。为了降低运输难度,原油需要在高温、高压条件下输送,但这样会导致海底管线发生温度应力下的整体屈曲,因此揭示海底管线发生整体屈曲的机理,建立温度荷载作用下管线整体屈曲的分析方法具有重要的理论意义和实用价值。本文采用解析法与数值模拟法相结合的手段,对海底管线水平向整体屈曲产生机理和模拟分析方法进行了系统研究。研究内容如下:对理想状态下海底管线水平向整体屈曲进行了分类,针对不同屈曲模式的管线建立了数学和力学分析模型;应用理论力学、材料力学、结构力学、高等数学等理论知识对管线屈曲的低阶模态进行求解,并推导相应的解析解,进而分析海底管线和土体之间的摩擦系数、输油温度、屈曲内力和屈曲幅值之间的关系;提出了采用改进的Riks算法并构建温度场和温度流模型、合理设置海底管线和地基土体之间接触关系,实现了对温度应力下海底管线水平向整体后屈曲的数值模拟;应用ABAQUS有限元软件,对具有不同初始缺陷的管线进行了模拟分析,研究海底管线在温度流和温度场这两种热荷载作用下,水平向整体屈曲的发生及发展规律,将分析结果与解析解进行了对比。研究表明,海底管线与土体之间的摩擦系数对理想管线的水平向整体屈曲有很大影响,当仅考虑低阶屈曲模式时,海底管线更易发生第二种模式的水平向整体屈曲;当初始缺陷较小时,管线拱起幅值与温度的关系曲线出现不稳定现象,而当初始缺陷较大时管线的屈曲呈渐变型;随着管线初始缺陷幅值的增加,管线发生水平向整体屈曲的临界温差降低;考虑管线输油温度沿程损失时,得到的海底管线水平向整体屈曲临界温差和屈曲应力都较小。更多还原

【Abstract】 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.更多还原