水下管汇坠物撞击变形及在波流作用下的动力响应研究

发布时间：2018-10-23 20:33

【摘要】：水下管汇作为开发油气田的一种重要方式,已被世界上大多数国家广泛研究和应用。水下管汇在安装以及服役期间都处于非常复杂海洋环境中,随时都可能会受到坠物冲击荷载以及风、浪、流等荷载的作用。一旦水下管汇失效,乃至引起泄露事故,不仅会影响油气的生产活动,造成严重的经济损失,泄露的油气等还会造成环境污染,给海洋生态系统带来灾难。所以,对水下管汇的碰撞以及动力响应进行分析研究,提前做好预防措施,对水下管汇的安全运行具有一定的指导意义。首先,参考DNV-RP-F107中海底管道受坠落物撞击概率的计算模型,建立水下管汇的撞击概率计算模型,给出一次抛锚事故中水下管汇受撞击概率的数值计算方法,并对水下管汇的锚击概率进行了参数分析。其次,本文对由抛锚作业引起的水下管汇的碰撞损伤进行计算分析。通过大量的数值模拟得出:在同一冲击能量下,锚与水下管汇的接触面积越小,即水下管汇损伤面积越小,则管汇的损伤深度越大,且水下管汇的应力达到屈服强度所需要的冲击能量越小,越容易发生塑性变形;冲击能量越大,水下管汇的损伤变形越大;冲击能量较小时,海床土体的剪切弹性模量对管汇的凹陷损伤深度和最大等效应力的影响比较小,冲击能量较大时,管汇的凹陷损伤深度和最大等效应力会随着海床土体剪切弹性模量的增大而增大;海床土体的内聚力和内摩擦角的变化对管汇的凹陷损伤深度及等效应力的影响相对比较小。最后,本文建立水下管汇的模型,对水下管汇在波浪、海流荷载作用下的动力响应进行计算分析。波流作用下水下管汇在X、Y方向的水平运动及转动为不规则的周期性运动。波高增加,管汇的运动频率增加,水下管汇在X、Y方向的线位移幅值和角位移幅值也随之增加。波浪周期增加,水下管汇在X、Y方向的线位移幅值和角位移幅值有减小的趋势。管汇入水深度增加,水下管汇在X、Y方向的线位移幅值和角位移幅值都明显变小,而且管汇的运动频率明显减弱。
[Abstract]:As an important way to develop oil and gas fields, underwater pipe sink has been widely studied and applied in most countries in the world. The underwater pipe sink is in a very complex marine environment during installation and service, and may be subjected to the impact of falling objects, wind, wave, current and other loads at any time. Once the underwater pipe sink fails or even causes leakage accidents, it will not only affect the production activities of oil and gas, cause serious economic losses, but also cause environmental pollution and bring disaster to marine ecosystem. Therefore, the collision and dynamic response of underwater tube sink are analyzed and studied, and the preventive measures are done in advance, which has certain guiding significance for the safe operation of underwater pipe sink. First of all, referring to the calculation model of the impact probability of the submarine pipeline falling in DNV-RP-F107, the model of the impact probability of the underwater pipe sink is established, and the numerical calculation method of the impact probability of the underwater pipe sink in an accident of breaking down is given. The anchoring probability of underwater pipe is analyzed. Secondly, the collision damage of underwater pipe sink caused by anchor operation is calculated and analyzed. Through a large number of numerical simulations, it is concluded that under the same impact energy, the smaller the contact area between the anchor and the underwater tube sink, that is, the smaller the damage area of the underwater pipe sink, the greater the damage depth of the pipe sink. And the smaller the impact energy required for the stress of the underwater tube sink to reach yield strength, the easier the plastic deformation will occur; the greater the impact energy, the greater the damage and deformation of the underwater pipe sink; the smaller the impact energy, the smaller the impact energy. The shear elastic modulus of the seabed soil has little effect on the damage depth and maximum equivalent stress of the pipe sink, and when the impact energy is large, The indentation damage depth and maximum equivalent stress increase with the increase of shear elastic modulus of seabed soil, and the change of cohesion force and friction angle of seabed soil have little effect on the indentation damage depth and equivalent stress of pipe sink. Finally, the model of underwater pipe sink is established, and the dynamic response of underwater pipe sink under the action of wave and current is calculated and analyzed. Under the action of wave and current, the horizontal motion and rotation of the underwater tube in the XY direction are irregular and periodic. With the increase of wave height, the moving frequency of the tube sink increases, and the linear displacement amplitude and the angular displacement amplitude of the underwater tube sink in the XY direction also increase. With the increase of wave period, the linear displacement amplitude and angular displacement amplitude of the underwater tube converge in the XY direction have a decreasing trend. With the increase of the water inlet depth, the linear displacement amplitude and the angular displacement amplitude of the underwater pipe sink in the XY direction become smaller obviously, and the moving frequency of the pipe sink is obviously weakened.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE53

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