深海缓坡型脐带缆干涉分析研究

摘 要：对深海缓坡型脐带缆设计参数敏感性及管线之间干涉进行了研究。随着油气开采向深海加速迈进,脐带缆的结构变得更加复杂,重量不断增加,致使顶端张力越来越大,采用缓坡构型可有效减小顶端张力,然而浮力块的引入使得其非线性动力特性更加显著,容易与其他构件发生碰撞造成内部光纤等构件破坏,导致通信中断并影响到整个油气安全生产,因此有必要对深海缓坡型脐带缆进行干涉分析。对环境载荷作用下缓坡型脐带缆位构型的方位角、拖曳力系数及浮力块半径等影响参数进行分析,分析结果表明脐带缆位置构型与这些参数之间有很大相关性,并对SPAR平台上脐带缆之间及张力腿平台中脐带缆与张力腿之间的干涉问题进行了分析,所给出的结论便于设计人员更好理解缓坡型脐带缆干涉动力特性。     

悬索桥主缆初始位形的悬链线方程精细迭代分析法

悬索桥非线性有限元法采用悬链线单元精度高,推导了基于自重约束方程,求解两种设计条件下主缆初始位形的悬链线精细迭代法公式,该方法能够计算主缆变形后自重荷载集度的变化.根据索鞍的受力特点,推导了不平衡索力与索鞍预偏量之间增量函数形式的显式刚度方程,导出了索鞍弧顶主缆曲线的无应力索长的精确计算公式.算例结果表明,方法精度高,计算稳定且收敛快.     

全海深ROV非金属铠装脐带缆动力学性能研究

为了全面评估全海深无人遥控潜水器(ROV)在不同模式配置、不同作业深度及工况下的脐带缆受力状态,提高脐带缆在全海深ROV系统应用的安全性和可靠性,开展了全海深ROV非金属铠装脐带缆动态力学理论分析与研究。针对铠缆系统水下运动具有小应变和大位移的几何特点,基于几何精确梁理论和虚功原理建立全海深非金属铠装脐带缆三维非线性有限元模型,基于所建立的动力学模型并结合工作母船升沉与海流联合激励,对脐带缆在全海深应用环境下扭转特性、在位运行等动态力学特性进行分析和研究。实验结果得出5000 m左右潜深为该全海深脐带缆系统的共振区域。研究结果可为全海深ROV非金属铠装脐带缆的安全应用及配套绞车优化设计提供理论依据。     

钢悬链线立管振动响应影响因素分析

海洋立管内部一般有高压的油或气通过,这将对立管的振动响应产生较大的影响。首先研究SCR管内流体的流速对结构固有频率的影响,结果表明：立管的固有频率随着管内流体流动速度的增加而降低,应在设计时予以足够重视。另外又分析悬链线立管张力随水深的变化规律,计算考虑变张力的立管固有频率,比较分析弯曲刚度对固有频率的影响。结果表明：弯曲刚度对前10阶频率影响不大。因此,在计算低模态的涡激振动时,可以忽略弯曲刚度的影响。     

深海钢悬链立管时域疲劳寿命预估研究

研究了钢悬链立管(SCR)时域非线性动力分析用于疲劳寿命预估。随着海洋工业不断往深海进发,过去十年内钢悬链立管成为众多油田开发的优选方案。然而,对于钢悬链立管设计而言疲劳是个关键难题。钢悬链立管的非线性动力特性显著,与频域方法相比,时域分析能够模拟非线性水动力载荷以及结构的非线性特性。本文数值模拟了海洋环境载荷作用下SCR的非线性结构动力响应,利用S-N曲线对立管进行整体疲劳寿命预估。对影响SCR疲劳寿命的各参数进行敏感度分析,输入的敏感度分析参数包括拖曳力系数、浮力因子、海床土体硬度等,研究表明疲劳寿命的预估结果与这些参数相关,所给出的结论便于设计人员更好理解钢悬链立管动力特性,选择合适的参数用于立管疲劳设计。     

浮体垂荡激励下深海悬链线立管触地端动力响应及沟槽发展研究EI北大核心CSCD

基于Randolph-Quiggin非线性管土作用模型,借助ABAQUS Subroutine功能中的User Defined Element(UEL)拓展模块创建钢悬链线立管触地单元,研究了顶端垂荡激励下立管触地段动力响应特性。通过与模型试验结果比较分析,验证了开发的数值分析模型的合理性,并讨论了其相较传统线性管土作用模型体现出的优势。开展参数敏感性分析,深入探讨了立管顶端垂荡幅值及周期对沟槽形状、立管位移及弯矩响应等的影响效应。     

基于能量分析的拎手绳打结研究

目的为了设计拎手绳自动打结机而分析能量与拎手绳打结状态的关系。方法分别以悬垂约束时,缠绕1圈后和成结时的拎手绳为分析对象,利用悬链线理论建立拎手绳的二维数学模型;通过弧长方程、变分法里的Euler-Lagrange方程等,分析拎手绳在悬链线状态下的势能;通过平面曲线的Frenet方程、弯曲能量方程及扭转能量方程等,对用于打结的绳段弯曲能量和扭转能量进行分析,并进行打结试验验证。结果拎手绳在悬链线状态下势能最小;拎手绳在缠绕过程中,弯曲的形状越接近规则圆、拎手绳自身的扭转数越少,绳子的能量就越小。结论打结过程中拎手绳的状态选择决定了绳子能量的大小,能量越小绳子就越趋于稳定,打结成功率越高。     

剪切流下钢悬链线立管涡激振动响应研究

给出线性轴向张力下顶端张紧式立管忽略弯曲刚度时的固有频率和模态振型解析解,与Shear7给出的结果进行比较。结果表明:在低于20阶模态数时,两种方法得到的固有频率能很好地符合;在高于20阶模态数时,随模态数的增加,两种方法得到的固有频率结果差距也逐渐变大,因此弯曲刚度不能忽略。由悬链线方程将钢悬链线立管等效为顶端张紧立管,通过研究顶端张紧式立管的涡激振动响应来研究钢悬链线立管的涡激振动响应。研究发现钢悬链线立管的静态位移与转化之后的等效立管均方根位移组成了类似于锯条的形状。     

钢悬链线输流立管顶部浮体激励非线性响应研究

钢悬链线立管在上部附体激励作用下的动力响应在立管的性能化设计中是非常重要的。本文作者考虑钢悬链线立管轴向大应变的特性以及弯曲刚度和内流的影响,利用Hamilton原理和拉格朗日应变理论建立了立管的二维动力学模型。将外部流体的非线性作用力用Morison方程表示,通过Hermite插值函数对动力学方程进行离散,采用平均加速度法求解立管的动力响应。探讨了弯曲刚度的存在、内流流动和外部流体的非线性作用力对立管受浮体激励顺流向动力响应的影响。     

水产养殖设施与深水养殖平台工程发展战略

设施与装备是我国发展环境友好型养殖业的重要保障。要坚持生态优先、绿色发展的理念,转变过去粗放型养殖生产方式,就必须大力开展设施装备技术研究,努力提高我国装备技术水平。只有这样,才能促进我国水产养殖业健康持续地发展。本文重点介绍了我国水产养殖装备设施应用现状、发展水产养殖工程面临的主要问题和发展水产养殖工程应用的关键技术,并提出了对策建议,以期为今后的设施与装备的研发提供借鉴。     

长江口深水航道治理工程的创新

经不断探索，依靠技术创新和严格、科学的管理，史无前例的长江口深水航道治理工程在复杂、恶劣的自然条件下取得了成功。文章论述了这一大型水运工程在设计、施工和管理方面创新的思维、作法和效果。     

深水、超深水钻完井标准梳理

为确保深水、超深水钻完井作业有据可依、安全可靠,通过对国内外各类相关标准的分析,梳理出了我国深水、超深水钻完井工程需采标（超深水井控、开发井钻完井设计和作业等）和制修订的标准（井场勘察、装备选择与设计等）,供国内深水、超深水钻完井作业参考,     

Risk Identification and Mitigation Strategies for Deepwater Oilfields Development

Deepwater oilfields will become main sources of the world’s oil and gas production. It is characterized with high technology, huge investment, long duration, high risk and high profit. It is a huge system project, including exploration and appraising, field development plan (FDP) design, implementation, reservoir management and optimization. Actually, limited data, international environment and oil price will cause much uncertainty for FDP design and production management. Any unreasonable decision will cause huge loss. Thus, risk foreseeing and mitigation strategies become more important. This paper takes AKPO and EGINA as examples to analyze the main uncertainties, proposes mitigation strategies, and provides valuable experiences for the other deepwater oilfields development.     

Strategies of Efficient Exploration and Development of Deepwater Oil and Gas Overseas

Deepwater offshore area, with rich oil and gas resources, has currently become the hot area for oil and gas exploration and the main battlefield where global oil majors compete with each other. This article summarizes the current situation of deepwater oil and gas exploration and development overseas from the perspectives of exploration history, exploration achievements and technical progress, and analyzes the difficulties and challenges faced by the industry, such as low level understanding of hydrocarbon accumulation conditions, global security and environmental challenges. And then, several feasible implementation strategies have been proposed on how to actively deal with the challenges, promote Chinese oil companies’ overseas exploration, and realize efficient exploration and development of deepwater oil and gas fields overseas. These strategies consist of three aspects: profit-oriented operation principle, exploration ideas supported by theory and technology, and exploration strategy that puts safety first. In the era of low oil prices, Chinese oil companies must build up confidence, seize the opportunity and face the challenge while taking efforts to innovate technologies and theories, updates strategic ideas, and cultivate deepwater talents so as to be in an active position in global deepwater exploration and development industry in the future.     

模拟深水环境爆炸容器动力响应实验研究

对可模拟200 m水深、10 g TNT当量的爆炸容器在不同加载静压和内部爆炸载荷下的动力响应进行了实验研究,通过监测容器6个特征点的动态应变波形,分析了容器壳体的振动特性和动力学强度。测试结果揭示了在加载静压和内部爆炸载荷条件下容器的动态响应规律,为模拟深水环境爆炸容器的设计研制提供了参考。     

Elasto-plasto overall response in single and mixed mode crack configurations

This paper deals with stress-strain fields and strain energy density distribution in single and mixed mode crack configurations.To avoid stress singularity in the neighbourhood of the crack tip a proper physical-mathematical model has been devised, where plasticization effects are taken into account. Following the Dugdale model, a continuous fictitious crack extension is realized. In this way the original nonlinear boundary-value problem is reduced to a linear one that is of elastic-perfectly plastic type.The governing equations are derived within the mathematical framework of free boundary problems, and the solution is evaluated by a numerical procedure based on the incremental loading method and the Williams' stress function.Experimental investigations, by using the optical method of caustics have been carried out, evaluating the SED distributions and the fracture angles for several crack configurations.

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Résumé L'étude est relative aux champs de contraintes-dilatations et à la distribution de la densité de déformation dans des configurations de fissures de modes simple et mixte. En vue d'éviter une singularité de contraintes au voisinage de l'extrémité de la fissure, on a conçu un modèle physico-mathématique adéquat, où l'on prend en compte les effects de la plastification. En suivant le modèle de Dugdale, on arrive au concept d'extension continue d'une fissure fictive. De la sorte, le problème initial des valeurs aux limites non linéaires est ramené à un problème linéaire de type élastique-parfaitement plastique.Les équations directrices sont établies dans le cadre mathématique des problèmes aux limites non définies, et la solution est évaluée par une procédure numérique basée sur une méthode de mise en charge par incréments et par la fonction de contraintes de Williams.On effectue également des travaux expérimentaux en utilisant la méthode optique de la caustique, pour évaluer les distributions de densité d'énergie de déformation et les angles, pour diverses configurations de fissures.

     

Influence of overall structural response on perforation of concrete targets

The influence of the overall structural response on the perforation of a concrete target is studied in this paper. The local perforation of the concrete target is idealized as a combined penetration and cone-plugging model. The overall structural response is simplified as an elastic, perfectly-plastic single degree of freedom (SDoF) model. A dimensional analysis is conducted to identify influential non-dimensional numbers in this problem to obtain non-dimensional governing equations. It is shown by parametric analyses that the overall stiffness and the overall strength of the concrete structure may influence the local perforation of the concrete target, which may help plan further experiments and numerical studies. The parameters introduced in the SDoF model can be obtained from actual concrete structures by using definitions of equivalent parameters, which has been generally accepted in dynamic structural analysis.     

The contribution of star scientists to overall sex differences in research productivity

The state of the art on the issue of sex differences in research efficiency agrees in recognizing higher performances for males, however there are divergences in explaining the possible causes. One of the causes advanced is that there are sex differences in the availability of aptitude at the “high end”. By comparing sex differences in concentration and performance of Italian academic star scientists to the case in the population complement, this work aims to verify if star, or “high-end”, scientists play a preponderant role in determining higher performance among males. The study reveals the existence of a greater relative concentration of males among star scientists, as well as a performance gap between male and female star scientists that is greater than for the rest of the population. In the latter subpopulation the performance gap between the two sexes is seen as truly marginal.