考虑阻尼海底悬跨段管道的动力特性及允许悬空长度

以海底悬跨段输液管道为研究对象,考虑管道结构阻尼、流体附加阻尼、管内流体流动及管道轴向力和压强的作用,对其进行受力分析,导出管道振动微分方程,进而得到管道动力特性方程。用Hermit插值函数对管道的动力特性方程进行离散得到有限元表达式,采用复模态分析法,求得管道的自振频率。为防止管道发生横向涡激振动,用约化速度作为控制条件,确定管道允许悬空长度。结果表明,管道允许悬空长度随着内流流速、轴向压力和管内压强的增加而减小,随着轴向拉力的增加而加大。     

受落物荷载作用海底管道保护的风险评估

海洋工程具有很高的风险,一旦发生恶性事故,就会导致巨大的环境污染和经济损失。尤其是作为海洋石油工程生命线的海底管道,其风险应努力降至最低。然而,货物坠落等事故是不可能避免的。由于受很多不确定性因素的影响,受落物荷载作用管道保护的风险评估课题是很复杂的。文中介绍了风险评估方法。首先讨论了几种确定风险接受准则的方法,它是整个风险分析的基础。接下来从整体角度对风险评估方法进行了解释。最后结合渤海油田某平台设计中的一个工程算例,详细给出了风险评估的具体计算过程,可用此计算方法来解决渤海油田中类似的问题。     

An integration of multi-criteria decision making techniques with a delay time model for determination of inspection intervals for marine machinery systems

For certain critical equipment items in marine machinery systems, the optimum maintenance strategy would be a scheduled on-condition operation. This involves inspection of the equipment items in order to monitor their performance degradation and, invariably, carry out repair or replacement tasks. The main challenge with this type of maintenance approach is the determination of the appropriate interval for performing the inspection task. This paper presents a methodology which integrates multi-criteria decision making (MCDM) tools with a delay time model for the determination of optimum inspection intervals for marine machinery systems. With this approach, multiple decision criteria are modelled with the delay time concept and aggregated with MCDM tools such that different criteria can be applied simultaneously in the ranking of different inspection interval alternatives. The applicability of the proposed methodology is demonstrated using the case study of a water cooling pump of the central cooling system of a marine diesel engine.     

海南岛南部近海海底输气管道检测和安全性评价

文章采用磁力测量和侧扫声呐测量方法,对海南岛南部近海海底输气管道进行检测,并根据检测结果开展管道安全性评价。研究表明,研究区海底地形较平坦;检测范围完全覆盖预计区域;小部分管道呈现半裸露状态但未危及安全,管道整体状态良好。定期或不定期对海底输气管道进行检测,可保证管道安全,避免天然气泄漏造成海洋环境污染。     

Condition Identification Based on Vibration Measurements for Free Spanning Submarine Pipelines

Free spanning pipelines are suspended between two points on an uneven seaffoor. The variations of structural conditions, such as the changes in soil property, flow velocity, axial force and span length etc., directly affect working performance of the whole submarine pipeline system. But until now few researches have focused on condition identification for free span （CIFS）. A method to identify the operational conditions of free spanning submarine pipelines based on vibration measurements is proposed in this paper. Firstly, the ill-posedness of CIFS is analyzed in detail. Secondly, the framework for CIFS based on the nonlinear kernel discriminant analysis （KDA） is established. Thirdly, the internal structural characteristics of natural frequencies, normalized frequencies and frequency change ratios are studied. And then the condition feature vector for CIFS is extracted by use of the vibration measurements. Finally, the validity of the proposed approach is evaluated by a case study. The results demonstrate that the proposed approach can effectively identify each condition of free span when condition variation occurs even if under measurement noise. It is concluded that the proposed method is a promising tool for CIFS in real applications.     

关于编制用海项目竣工验收测量技术规程的探讨

文章针对当前填海竣工验收管理工作有管理办法但缺乏验收规范的情况,从科学意义和应用管理角度,提出编制用海项目竣工海域使用验收测量技术规程的迫切性和必要性,提出不仅需要对填海项目竣工验收制定验收技术规程,还应该对构筑物用海、海底管线用海等不同用海类型和方式特点,采用有针对性的竣工测量边界界定原则和竣工验收测量方法,分析误差限值建议说明,以期为沿海各省、市、自治区海域行政管理人员和竣工测量单位提供参考。     

Numerical study on lateral buckling of pipelines with imperfection and sleeper

Lateral buckling is an important issue in unburied high-temperature and high-pressure (HT/HP) subsea pipelines systems. The imperfection–sleeper method is one of the most well-known methods used to control lateral buckling of HT/HP pipelines. Pipelines–sleeper–seabed numerical models are established and verified to analyze the buckling behavior of pipelines using the imperfection–sleeper method. The influence of six main factors on lateral buckling behavior is investigated in details based on the numerical results. Equations of buckling displacement (buckling displacement is defined by the final displacement of the middle point of the pipelines), critical buckling force, and buckling stress (Mises stress) are proposed using the gene expression programming technique. These equations show good accuracy and can be used to assist in the design of sleepers and assess the compressive and stress levels of pipelines.     

Dynamic analysis of wave energy converter by incorporating the effect of hydraulic transmission lines

A heaving-buoy wave energy converter equipped with hydraulic power take-off is studied in this paper. This wave energy converter system is divided into five subsystems: a heaving buoy, hydraulic pump, pipelines, non-return check valves and a hydraulic motor combined with an electric generator. A dynamic model was developed by considering the interactions between the subsystems in a state space form. The transient pressures caused by starting/stopping the buoy or closing/opening the check valves were predicted numerically using the established model. The simulation results show that transmission line dynamics play a dominant role in the studied wave energy converter system. The length of the pipeline will not only affect the amplitude of the transient pressures but also affect the converted power. The variation of the time-averaged converted electric power with the pipeline length is estimated using the simulation method for the buoy exposed to one irregular sea state. Finally, it is suggested how reduced power efficiency due to the pipelines may be ameliorated.     

水声环境资料质量检核评估标准规范研究

为规范水声环境资料质量检核评估工作,开展了水声环境资料质量检核评估标准规范研究,参照水声环境数据后期处理一般程序,梳理分析了原始数据、处理算法、模型运用及处理流程等数据质量误差来源;结合标准化水声环境资料处理程序及成果形式,研究了数据及数据处理全流程检核评估方法,给出数据文件、处理代码及配套文档资料应包含的内容及检查方...     

Effect of Internal Flow on Vortex-Induced Vibration of Submarine Free Spanning Pipelines

At present, most researches on the vortex-induced vibration of submarine free spanning pipelines ignore the effect of internal flowing fluid; furthermore, there are no research reports considering the coupling effect of internal and external fluid with the free span. In this paper, combining Iwan‘s wake oscillator model with the differential equation derived for the dynamic response of submarine free spanning pipelines with inclusion of internal flow, the pipe-fluid coupling equations are developed to investigate the effect of internal flow on the vortex-induced vibration of the free spans. The finite dement approximation is implemented to derive the matrix equations of equilibrium. The Newmark method combined with simple iteration is used to solve the system of equations. The results indicate that the internal fluid flow may cause the shift of resonance band to the lower frequency and a slight decrease in the peak value; the effect will be mare pronounced with the increase of the span length and can be weakened in the presence of the axial tension.     

含初始缺陷海底管道侧向屈曲临界力的参数解

未埋设的海底管道在高温高压运行条件下可能发生侧向屈曲,情况严重时影响海底管道的结构安全。侧向屈曲临界力作为判定海底管道发生侧向屈曲的重要依据,主要影响因素有初始缺陷、管土相互作用等。现有关于侧向屈曲临界力的公式并未考虑管土相互作用、缺陷不平直度和管道自身材料特性对侧向屈曲临界力的综合影响。建立含有通用几何初始缺陷海底管道的数值模型,使用Riks算法进行参数分析以研究极限侧向土壤阻力、管道缺陷不平直度和截面几何尺寸对海底管道侧向屈曲的具体影响。基于量纲分析法和多元线性回归,推导出海底管道侧向屈曲临界力关于上述3个影响参数的一般公式,并对该公式进行了检验,结果表明文中推导的公式在参数涵盖的研究范围内有效。     

Theoretical analysis of type II dent pipe under external force

In-service pipelines are often subject to external disturbances that produce dent defects, and the presence of dent defects often affects the pipeline's ultimate bearing capacity. This paper analyzes the equilibrium state of dent pipelines under external force for in-service pipelines with type II dent defects. A simplified calculation model for the shell is established through a series of assumptions and simplifications. Firstly, the pipe ring is crushed and analyzed to obtain the crushing power of the pipe ring, and then the pipe generator is subjected to deformation analysis to obtain the generator dissipating power. According to the principle of virtual work, the relationship between the external force power and the internal power dissipation power in equilibrium state is obtained.Under the condition of internal pressure, the type II dent defect is analyzed, and the relationship between the external force and the depth of the dent defect and its corresponding analytical expression are obtained. Under the condition of no internal pressure, the dent defect under different constraints is analyzed, and the analytical expression of the applied load under different constraints is obtained.     

多跨海底管道横流向涡激振动预报模型

基于欧拉-伯努力梁理论确定了多跨管道结构振动方程,采用非线性Van der pol方程描述旋涡脱落的尾流动力特性,利用弹簧模拟两端和中间的复杂边界约束,构建了多跨海底管道横流向涡激振动预报模型。基于模态正交性展开流-固耦合作用方程,对各阶主坐标响应进行数值求解。对比了本模型预报结果与试验结果、软件分析以及DNV规范推荐值,吻合情况比较理想。本模型可为深海多跨管道涡激振动的研究、防范和治理提供有效的分析方法。     

侧扫声纳在海底管道悬空调查中的应用

海底管道在铺设及运营过程中,受各种因素的影响,会形成部分悬空状态。为保证油管的安全运营,研究了一种基于声学的快速检测方法:主要利用侧扫声纳获取油管附近声学影像,通过数据判读的方法分析并获取管线状态。然后使用该方法,在册镇海底管线调查中进行了应用测试。声学检测结论与水下探摸结果进行比较,测试结果表明该方法可高效、快速、准确并低成本地检测管线状态,可为海底管道运营与治理提供有力的技术支持。     

A semi-analytical method of stress-strain analysis of buried steel pipelines under submarine landslides

A semi-analytical method of the stress-strain analysis of buried steel pipelines under submarine landslides was proposed, considering the nonlinearities of the pipe-soil interaction and mechanical properties of the pipe steel. The pipeline was divided into three parts according to different loading conditions, and the corresponding differential equations were established based on a combination of the beam-on-elastic foundation and elastoplastic-beam theories. According to the second-order central difference method, the transverse horizontal displacement was calculated, and then the bending strain was obtained based on the relation between bending strains and curvatures. Considering the interaction between the axial and bending strains, the axial strain can be derived from the equilibrium condition by equating the axial force. The proposed method was verified through the comparison of obtained solutions to ANSYS results, with minor deviations which do not exceed about 4.6%. Additionally, the effects of the slide width, the buried depth of pipelines, the internal friction angle of soils, the cohesion of soils and the bulk density of soils are investigated through parametric studies.     

Experimental and finite element study on lateral global buckling of pipe-in-pipe structure by active control method

Offshore oil and gas exploration are gradually heading toward the deep sea and even the ultra-deep sea. According, the working temperature and pressure intensity of subsea oil and gas pipelines have increased by a considerable degree. This situation is accompanied by the global buckling problem in deep sea pipelines, which has become increasingly common. Meanwhile, ordinary single-layer pipelines cannot last for a long time under harsh deep-sea working conditions. Thus, multilayer pipelines, such as the pipe-in-pipe (PIP) structure and bundled pipelines, have gradually become top choices. However, the global buckling mechanisms of these multilayer pipelines are more complicated than those of single-layer pipelines. The sleeper–snake lay pipeline, which is an active control method for global buckling, was used in this study. The change and development laws of global buckling in a PIP structure at different wavelengths and amplitudes were determined through an experimental study. A dynamic solution method that considers artificial damping was adopted to establish finite element global buckling models of a PIP structure with initial imperfections. The effects of various factors, such as pipeline laying shape, sleeper–pipe function, and seabed–pipe function, on global buckling were analyzed. By the result of finite element method analysis, the initial imperfection, and sleeper–pipeline friction were determined to be the key factors that influenced critical pipeline buckling force. Accordingly, a reference for the design of PIP structures is presented.     

影响海洋平台检测质量因素的模糊综合评判分析

本文通过对海洋平台结构实际检测工作的调查分析，着重研究了检测人员的失误对检测质量影响的主要因素，并运用模糊数学的基本理论，对包括人因素，非人因素。进行了多级模糊综合评判，建立了相应的对检测质量影响的理论模型。为验证所建立的数学模型的正确性和有效性，进行了数值实例计算。计算分析结果表明，本文所建立的理论分析模型是比较科学合理的，能较好地分析人的因素对检测质量的影响，为平台结构的完整性、可靠性以及剩余寿命的评估提供了基础和依据     

Study on Interaction Relationship for Submarine Pipeline with Axial Corrosion Defects

Corrosion is one of the main reasons to cause the operation accident of submarine oil and gas transmission pipelines. As the major corrosion pattern in submarine pipelines, the effects of corrosion clusters consisting of the adjacent corrosion defects on failure pressure are investigated through non-linear large-deformation finite element method. Typically, the failure behavior and limit strength of submarine pipeline with axial groove-groove corrosion defect pair exposed to internal pressure are analyzed. The effects of corrosion depth and axial spacing between a pair of corrosion defects on failure pressure are concluded. An interaction relationship for corrosion defects in pipelines, as well as prediction formulations for assessing the remaining strength of corroded pipelines are proposed. The expressions based on the proposed interaction relationship give more accurate results than the methods used in the existing design guidelines.     

Hydroelastic response of marine risers subjected to internal slug-flow

It is the purpose of this study to investigate the dynamic behaviour of catenary pipelines for marine applications, assuming the combined effect of harmonic motions imposed at the top, and the internal slug-flow. The analysis is based on the assumption of a steady slug-flow inside the pipe that results in a relatively simplified model for the formulation of the internal flow. The slug-flow model is described using several assumptions and empirical correlations which attempt to reveal the ill-understood and concealed properties of the slug-flow. The pipeline dynamics are investigated in the two dimensional space omitting the out-of-plane vibrations. The system of differential equations is generic and accounts for the steady effect of the internal liquid as is conveyed through the structure.The two models, those of the internal slug-flow and the pipeline’s dynamical model, are properly combined through the internal flow terms of the dynamic equilibrium system. The solution provided is achieved using a frequency domain technique which is applied to the linearized governing set. The effect of the slug-flow is assessed through comparative computations with and without internal flow effects. The conclusions are drawn having the structure excited under axial and normal motions paying particular attention to the variation of the dynamic components along the complete length of the pipeline.     

海底输油管道掩埋状况调查研究

本文用全球卫星接收定位系统（ＧＰＳ）与浅地层剖面系统（ＧｅｏＣｈｉｒｐ Ｓｕｂ－Ｂｏｔｔｏｍ Ｐｒｏｆｉｌｅ Ｓｙｓｔｅｍ）对珠江三角洲的铜鼓、伶汀、九州水 底输油管道掩埋状况进行勘测,全部数据记录在声纳图像增强工作站。经室内回放增强处理得出硬拷贝资料,然后将全部定位资料输入计算机用ＧＩＳ系统进行处理得出测线的ＫＰ点。解释出所测管道掩埋状况,文中列出了管道几种掩埋状况,为海洋工程调查研究提供参考。