深海悬链线立管触地区域疲劳及可靠性研究

发布时间：2018-06-22 07:46

本文选题：悬链线立管 + 浮体系统耦合模型　；参考：《上海交通大学》2014年博士论文

【摘要】：立管是连接海床和海洋平台的细长柔性构件，主要用于钻井和油气输送等。在各种类型的立管中，悬链线立管因具有安装简便、成本低、适合应用于多种平台类型等优点而在深海油气开采中得到越来越多的应用。尽管悬链线立管集诸多优点于一身，但其特殊的布置形式所带来的疲劳损伤一直是海洋工程领域的挑战性问题。如果能够充分考虑悬链线立管承受的环境载荷，并合理的模拟立管与海床的相互作用，那么可以大大提高触地点疲劳损伤的预报精度，从而避免偏大的安全因子给立管制造带来的额外费用。本文作为国家自然科学基金项目“基于海流随机性的深海立管涡激振动疲劳寿命概率预测方法研究”、国家重大科技专项“深水海底管道和立管工程技术”和海洋工程国家重点实验室自主研究课题“深海立管多模态涡激振动疲劳损伤特性研究”的重要组成部分，旨在深入研究深海悬链线立管触地点附近的疲劳损伤特性，并建立合理的疲劳损伤评估体系。本文根据国际上悬链线立管触地点疲劳损伤的最新研究动向，对悬链线与海床的相互作用、涡激振动的频域和时域预报技术、触地点的疲劳损伤特性及可靠性等开展了深入的研究，取得了积极的成果。论文的主要研究工作如下： (1)总结了已公布的管土作用实验和涡激振动实验，并详细归纳了平台系统耦合响应预报技术、管土作用模型、涡激振动模型以及立管疲劳分析方法的研究，阐述了有待补充和完善的内容。 (2)根据频域转时域理论，利用频域水动力系数开发了浮体时域单元。采用考虑几何非线性的三节点杆单元和梁单元模拟系泊索和立管，并通过推导的多点约束连接浮体单元与杆单元和梁单元，将浮体系统通过有限元组装到统一矩阵下，从而构建浮体系统全耦合预报模型。 (3)基于梁-弹簧模型编制立管初始嵌入海床的静力分析程序，研究了立管最大嵌入深度、海床刚度和立管重量对触地区域立管形状的影响。讨论了已有的海床沟槽模型，指出其中的不足，并根据墨西哥湾现场监测的沟槽形状提出了全新的海床沟槽模型。根据大尺度模型实验得到的垂向管土作用力的特性，提出了线性滞后的管土作用模型；海床的侧向作用通过与海床嵌入深度有关的弹簧模拟。结合沟槽模型、管土垂向和侧向作用模型，开发了与深海悬链线立管匹配的触地单元，并通过定性分析证明了触地单元能够有效的捕捉管土作用吸力的产生和释放过程。 (4)对刚性圆柱体受迫振荡和自激振荡得到涡激振动锁定区间的一致性进行了分析，提出了顺流涡激振动不同激发模态能量输入叠加区域的处理原则，在此基础上，利用受迫振荡实验数据建立了深海立管横流和顺流涡激振动频域预报模型，并通过一系列大尺度立管涡激振动模型实验进行了验证分析。利用开发的频域程序研究了触地区域存在对涡激振动诱发的触地点响应的影响进行了分析，阐明了传统截断模型得到触地点响应的不合理之处。 (5)针对涡激振动频域模型固有的缺陷，本文提出了适合涡激振动时域分析的立管单元锁定判断准则，并建了横流和顺流耦合涡激振动时域预报模型，，然后通过顶端张紧式立管和悬链线立管的涡激振动模型实验进行了验证。分析了悬链线立管模态振型所在的平面，并验证了涡激振动频域和时域预报方法将二维有限元模型得到的模态代替三维有限元模型模态的合理性。将管土作用模型与涡激振动时域模型结合，研究了海床参数对触地区域响应模态以及悬链线立管整体响应位移的影响。 (6)采用雨流计数法编制了疲劳损伤计算程序，并通过比较涡激振动诱发的立管实验模型疲劳损伤的数值结果和文献结果进行了验证。对于涡激振动的频域预报模型，对比分析了三种多模态诱发的疲劳损伤计算方法，并为横流和顺流涡激振动分别推荐了合适的方案。采用全耦合程序和涡激振动时域方法对深海悬链线立管进行了相应分析，讨论了触地区域的疲劳损伤对波浪参数和海床参数敏感性。比较了时域和频域方法得到的涡激振动诱发的触地区域疲劳损伤，进一步分析了前面推荐方案的合理性。 (7)分析了立管疲劳可靠性及疲劳安全因子的计算方法，并编制了响应面法、蒙特卡洛法和Rosenblueth法程序。结合全耦合模型和频域涡激振动预报模型，研究了涡激振动诱发的触地点疲劳损伤概率分布特征、疲劳失效概率对不确定性因素的敏感性，讨论了全耦合响应和涡激振动诱发的年疲劳失效概率与疲劳安全因子的关系。
[Abstract]:Riser is a long and flexible flexible component connecting seabed and offshore platform. It is mainly used in drilling and oil and gas transportation. In various types of risers, the catenary riser has been used more and more in deep sea oil and gas mining because of its advantages of easy installation, low cost and suitable for various types of platform types. The fatigue damage caused by the special arrangement has been a challenging problem in the field of marine engineering. If the environmental load of the catenary riser is taken into full consideration and the interaction between the riser and the seabed can be reasonably simulated, the prediction accuracy of the fatigue damage of the touchdown point can be greatly improved, thus avoiding the deviation. The extra cost for riser manufacturing caused by the big safety factor.
As the National Natural Science Foundation Project "study on the probability prediction method of vortex induced vibration fatigue life of deep-sea risers based on the randomness of ocean current", the national major science and technology special "deepwater seabed pipeline and riser engineering technology" and the National Key Laboratory of Marine Engineering "deep-sea riser multimodal vortex induced vibration fatigue" The important part of the study of damage characteristics is to study the fatigue damage characteristics near the touch site of the deep-sea catenary riser and establish a reasonable fatigue damage assessment system.
In this paper, according to the latest research trend of the contact point fatigue damage of the catenary riser, the interaction of the catenary and the seabed, the frequency domain and the time domain prediction technique of the vortex excited vibration, the fatigue damage characteristics and the reliability of the touchdown point are studied in this paper, and the positive results are obtained. The main research work of this paper is as follows:
(1) the published experimental and vortex induced vibration experiments have been summarized, and the research on the coupled response prediction technique of the platform system, the soil action model, the vortex induced vibration model and the riser fatigue analysis method are discussed in detail, and the contents to be supplemented and perfected are expounded.
(2) based on the frequency domain theory of time domain, a floating body time domain unit is developed by using the frequency domain hydrodynamic coefficient. The three node element and beam element considering geometric nonlinearity are used to simulate mooring cables and risers, and the floating body unit, rod element and beam element are connected by the derivation of multi point constraints, and the floating body system is assembled under the unified matrix by the finite element. Thus the full coupling prediction model of the floating body system is constructed.
(3) based on the beam spring model, the static analysis program of the initial embedded seabed in the riser is compiled. The influence of the maximum embedded depth of the riser, the seabed stiffness and the weight of the riser on the shape of the riser in the ground is studied. The existing model of the seabed groove is discussed, and the shortcomings are pointed out, and a new method is put forward according to the groove shape in the Mexico Bay. According to the characteristics of the vertical tube soil force obtained by the large scale model experiment, a linear lagging tube soil model is proposed. The lateral action of the seabed is modeled by the spring simulation related to the depth of the seabed embedding. The vertical and lateral action model of the pipe soil is developed to match the deep-sea catenary riser. Through the qualitative analysis, it is proved that the touchdown unit can effectively capture the process of the suction and release of the pipe soil action.
(4) the consistency between the forced oscillation and the self excited oscillation of the rigid cylinder is analyzed. The principle of processing the superposition region of the energy input of the different excitation modes of the vortex excited vibration is proposed. On this basis, the frequency domain prediction of the transverse and downstream vortex excited vibration of the deep-sea riser is established by using the experimental data of the forced oscillation. The model is verified by a series of large scale riser vortex induced vibration model experiments. Using the developed frequency domain program, the influence of the contact area on the ground contact point induced by the vortex induced vibration is analyzed, and the unreasonableness of the traditional truncation model is clarified.
(5) in view of the inherent defects of the vortex excited vibration frequency domain model, this paper proposes a lock judgment criterion for the riser unit, which is suitable for the time domain analysis of vortex excited vibration, and builds a time-domain prediction model for the transverse and downstream coupled vortex excited vibration. Then, the vortex induced vibration model experiment of the top tensioned riser and the catenary riser is verified. The mode of the mode of the linear riser is located, and the rationality of the mode of the two-dimensional finite element model is replaced by the frequency domain and the time domain prediction method of the vortex excited vibration. The response mode of the seabed parameters to the ground area and the catenary riser are studied by combining the soil interaction model with the time domain model of the vortex excited vibration. The effect of the overall response displacement.
(6) the fatigue damage calculation program is compiled by the rain flow counting method, and the numerical results and the literature results of the experimental model of the riser induced by vortex induced vibration are compared and the results of the literature are verified. In the frequency domain prediction model of the vortex induced vibration, three methods of fatigue damage induced by multimodal induced fatigue are compared and analyzed, and the transverse and downstream vortices are also calculated. The appropriate scheme is recommended respectively. The full coupling program and the time-domain method of vortex excited vibration are used to analyze the deep-sea catenary riser, and the sensitivity of the fatigue damage to the wave parameters and the seabed parameters is discussed. The fatigue damage caused by the vortex induced vibration induced by the time-domain and frequency domain methods is compared. One step is to analyze the rationality of the previous recommendation.
(7) the fatigue reliability of riser and the calculation method of fatigue safety factor are analyzed, and the response surface method, Monte Carlo method and Rosenblueth procedure are compiled. The probability distribution characteristics of the fatigue damage induced by vortex induced vibration are studied in combination with the full coupling model and the frequency domain vortex induced vibration prediction model, and the probability of fatigue failure is considered to be uncertain. The relationship between the full coupling response and the annual fatigue failure probability induced by vortex induced vibration and the fatigue safety factor is discussed.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P756.2

【参考文献】