【作者】 李静；

【导师】 王锡朝； 张春会； 田英辉；

【作者基本信息】 河北科技大学 ， 建筑与土木工程（专业学位）， 2020， 硕士

【摘要】 随着石油工业的不断发展,海底油气管道已经广泛的应用在石油和天然气的开采以及运输中。在海底油气管道的安装以及输送过程中,由于海上作业、平台操作、锚定处理、拖网活动、海上运输船只等第三方的人类活动,可能会经常发生由坠落物撞击管道而产生的各种意外事故,使得海底管道管壁产生较大的凹痕或者较大的裂缝。海底油气管道一旦发生失效,不仅可能会影响人类正常的生产经营活动,造成巨大的社会经济损失,甚至会严重污染海洋生态环境,造成灾难性的后果。因此,保证海底油气管道安全正常运行,需要对海底管道损伤情况进行全面的评估,从而制定出相应的安全保护措施。本文利用数值分析方法从海底管道和海床土体两个方面深入研究坠落物的撞击对海底管道造成的损伤程度,并提出在土体海床上坠落物对海底管道损伤的评估方法。首先在建模过程中考虑材料非线性、几何非线性以及接触非线性等因素对海底管道损伤的影响,采用有限元软件ABAQUS中的显示动力学方法来建立坠落物-海底管道-海床土体的撞击计算模型。其次对模型的准确性进行验证分析。第三,分析管道直径、管道壁厚、管道内压、管道钢材强度等级以及海床的土体参数等因素对海底管道损伤的影响。最后提出一个考虑土体海床作用下海底管道塑性变形能与管道损伤两者之间关系的经验公式。具体研究结论如下:1)管道塑性变形能与管道损伤两者之间存在一定的关系,随着管道吸收塑性变形能的增加,管道的损伤也逐渐的增加,而且管道塑性变形能与管道损伤两者之间的关系是一种非线性关系。2)管道的直径、管道的壁厚、管道的钢材等级、管道的内压全都影响着管道塑性变形能量与管道损伤的关系,管道吸收相同的塑性变形能时,管道损伤程度随管道直径、管道壁厚、管道钢材等级、管道内压增加而逐渐减小;土体不排水抗剪强度和弹性模量对管道塑性变形能量与管道损伤的关系基本没有影响。3)综合上述研究,提出了一个考虑土体海床作用下海底管道塑性变形能与管道损伤两者之间关系的经验公式,用来评估海底管道的损伤程度。更多还原

【Abstract】 With the continuous development of the petroleum industry,submarine oil and gas pipelines have been widely used in the exploration and transportation of oil and gas.During the installation and transportation of submarine oil and gas pipelines,various accidents caused by the falling objects hitting the pipelines may often occur due to the third-party human activities such as the offshore operations,the platform operations,the anchoring processing,the trawling activities and the offshore transport vessels.What’s more,the falling objects can cause large dents or large cracks on the wall of submarine pipelines.Once the submarine oil and gas pipeline fails,it may not only affect the normal production and operation activities of humans and cause huge economic losses,but also seriously pollute the marine ecological environment and cause disastrous consequences.Therefore,to ensure the safe operation of submarine oil and gas pipelines,it is necessary to conduct a comprehensive assessment of the damage of the submarine pipelines and formulate corresponding safety protection measures.In this paper,numerical analysis method is used to study the damage degree of the submarine pipeline caused by the impact of falling objects from the two aspects of the submarine pipeline and the soil seabed,and propose a method for evaluating the damage of the submarine pipeline caused by the falling object on the soil seabed.First of all,the influence of material nonlinearity,geometric nonlinearity and contact nonlinearity on the damage of submarine pipeline is considered during the process of building the model,and the display dynamics method in the finite element software ABAQUS is used to establish the impact calculation model of the falling object-the submarine pipeline-the soil seabed.Secondly,verify the accuracy of the model.Thirdly,analyze the influence of factors such as the diameter of the submarine pipeline,the thickness of the submarine pipeline,the internal pressure of the submarine pipeline,the strength grade of the submarine pipeline steel and the soil parameters of the seabed on the damage of the submarine pipeline.Finally,an empirical formula considering the relationship between the plastic deformation energy of the submarine pipeline and the pipeline damage under the action of the soil seabed is proposed.The specific research conclusions are as follows:1)There is a certain relationship between the plastic deformation energy of the pipeline and the damage of the pipeline.As the absorption of plastic deformation energyof the pipeline increases,the damage of the pipeline gradually increases.Moreover,there is a nonlinear relationship between the plastic deformation energy of the pipeline and the pipeline damage.2)The diameter of the pipeline,the wall thickness of the pipeline,the steel grade of the pipeline and the internal pressure of the pipeline all affect the relationship between the pipeline plastic deformation energy and the pipeline damage.When the pipe absorbs the same plastic deformation energy,the damage degree of the pipe gradually decreases with the increase of pipe diameter,pipe wall thickness,pipe steel grade and pipe internal pressure;the undrained shear strength and elastic modulus of the soil have basically no effect on the relationship between the energy of the plastic deformation of the pipeline and the pipeline damage.3)Synthesize the above research,an empirical formula considering the relationship between the plastic deformation energy of the submarine pipeline and the pipeline damage under the action of the seabed is proposed to evaluate the damage degree of the submarine pipeline.更多还原