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1.
考虑阻尼海底悬跨段管道的动力特性及允许悬空长度 总被引：8，自引：0，他引：8
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。 相似文献
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Study on Interaction Relationship for Submarine Pipeline with Axial Corrosion Defects 总被引：2，自引：0，他引：2
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. 相似文献
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海底双层管单层连接管道结构受力分析 总被引：1，自引：0，他引：1
粘性高的海洋石油通常需要通过海底保温管道加温输送.温度变化会引起管道变形,并在管壁内产生较大的温度应力.同时,管道正常运营期间还受到管道内压、外压、管内流体粘滞力和土体摩擦力等环境荷载的作用.复杂的环境可能导致海底管道轴向应力过大发生破坏.为了提高铺管效率,提出了双层管单层连接管道这一特殊管道形式,并从理论上分析温度变化和环境荷载对该管道的影响,计算正常运行时管道不同位置处横截面内最大Von-Mises应力.最后得到了Von-Mises应力沿管道轴线分布情况,发现内管和单层连接管的应力一般比外管大,变径管和内管的焊缝处是Von-Mises应力最大的地方. 相似文献
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含有腐蚀缺陷海底管道极限载荷分析 总被引：8，自引：0，他引：8
利用有限元弹塑性分析方法,对含有腐蚀缺陷的海底管道进行材料非线性和几何非线性分析,探讨了确定管道极限载荷的准则。在此基础上,给出含有腐蚀缺陷的海底管道的极限载荷,研究腐蚀长度、深度和宽度对海底管道极限载荷的影响,提出了含有腐蚀缺陷的受内压的海底管道的极限载荷计算公式,并与试验结果进行了比较,证明该方法是有效的。 相似文献
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De-feng Zheng Bo Liu Min Liu Ping Yin Yan-dong Huo 《Marine Georesources & Geotechnology》2019,37(1):116-127
The exploration and exploitation of marine georesources ordinarily disturbs the submarine soft clay surrounding construction areas and leads to a significant decrease in the shear strength of structured and sensitive clayey soils in submarine slopes. Under wave action, local slides can even trigger large-scale submarine landslides, which pose a serious threat to offshore infrastructure such as pipelines and footings. Therefore, accurately evaluating the stability of submarine sensitive clay slopes under wave-induced pressure is one of the core issues of marine geotechnical engineering. In this paper, a kinematic approach of limit analysis combined with strength reduction technique is presented to accurately evaluate the real-time stability of submarine sensitive clay slopes based on the log-spiral failure mechanism, where external work rates produced by wave-induced pressure on slopes are obtained by the numerical integration technique and then are applied to the work-energy balance equations. The mathematical optimization method is employed to achieve the safety factors and the critical sliding surfaces of submarine slopes at different time in a wave cycle. On this basis, the stability of submarine sensitive clay slopes under various wave parameters is systematically investigated. In particular, extreme wave conditions and special cases of slope lengths no more than one wavelength are also discussed. The results indicate that waves have some negative effects on the stability of submarine sensitive clay slopes. 相似文献
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海底管道是海洋石油主要的运输方式,但海底管道在外部静水压力作用下很可能发生局部屈曲压溃,造成灾难性后果。安装止屈器可有效阻止屈曲传播,保证管道安全,整体式止屈器在实际中应用最为广泛。整体式止屈器存在通过减小止屈器体积以节约成本进行优化的可能性,因此,在保证止屈器止屈效果的前提下,可通过减小止屈器的体积,以达到减轻重量、节约成本、减少安装难度等多种目的。研究过程中使用ABAQUS进行模型的仿真模拟,比较了广义弧长法的优缺点,决定选用更方便的静水流体单元法,计算得到不同止屈器的穿越压力以及相应的体积,对比各止屈器的穿越压力变化和体积变化,实现结构优化的目标。基于以上研究,可以得出减少止屈器体积的结构优化方案具有可行性的结论。 相似文献
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为了探索不同径厚比海底管道的压溃屈曲特性,本文分别采用挪威船级社（Det Norske Veritas,DNV）规范、有限元模拟和深海压力舱模型试验,研究不同径厚比海底管道承载外部水压的能力,并就DNV规范压溃屈曲计算公式对不同径厚比管道的适用性进行了讨论,优化了小径厚比海底管道压溃屈曲的设计方法。研究表明：小径厚比管道的压溃屈曲临界压力对管道径厚比的变化更敏感;DNV规范计算小径厚比管道的压溃屈曲临界压力偏小,在进行深海管道的压溃屈曲设计时,建议采用模型试验结合有限元模拟的方法,计算管道实际可提供的压溃屈曲承载力。 相似文献
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腐蚀是管道常见的缺陷形式之一,会极大降低管道的压溃压力,同时深海环境下高静水外压易引发管道压溃失效,威胁管道的安全运行,因此准确预测管道压溃压力显得尤为重要。采用数值模拟方法研究了含腐蚀缺陷的高强钢厚壁管道压溃失效模式,分析了管材、管道径厚比、腐蚀深度、长度和宽度等参数对高强钢厚壁管道压溃压力的影响规律。分析结果表明:管道径厚比愈大,对厚壁管道的承压能力提升愈显著;腐蚀缺陷的存在对管道压溃压力具有减小作用;随着管道材料等级的提升,压溃压力有明显提高。提出了相应的压溃压力预测公式,为厚壁管道完整性评价提供了参考依据。 相似文献
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1 .Introduction Submarine pipelines are one of the safest and the least environmentally disruptive means for ma-rine gas or oil transport . With the development of exploitation of submarine oil or gas ,the safety ofsubmarine pipelines has becomethe major … 相似文献
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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。 相似文献
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Mechanism of local scour around submarine pipelines based on numerical simulation of turbulence model 总被引：2，自引：2，他引：0
1 IntroductionSubmarine pipelines are important ocean engi-neeringequipm ents, especiallyfortheoiland gasin-dustries. M anyresearchershavebeendedicatedtotheproblem of local scour around the submarinepipelines, butmostoftheirwork arelaboratory testsand foc… 相似文献
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Because of the complex geological conditions of the seabed, submarine pipelines buried beneath the ocean floor become suspended over the seabed under the long-term scour of waves eroding the surrounding sediment. Further, most oil fields were built in offshore areas while the country was developing. This gives the waves seen in shallow water obvious nonlinear features, and the abnormal characteristics of these waves must be considered when calculating their hydrodynamic forces. Particularly under such conditions, these suspended spans of submarine pipelines are prone to damage caused by the action of the external environment load. Such damages and eventual failures may result not only in great property losses but also pollution of the marine environment. The span length of these areas is a key predictive factor in pipeline damages. Therefore, determining the allowable span length for these submarine pipelines will allow future projects to avoid or prevent damage from excessive suspended span lengths. Expressions of the hydrodynamic loads placed on suspended spans of pipeline were developed in this work based on the first-order approximate cnoidal wave theory and Morison equation. The formula for the allowable free span length was derived for the common forms of free spanning submarine pipeline based on the point where maximum bending stresses remain less than the material’s allowable stress. Finally, the allowable free span length of real-world pipelines was calculated for a subsea pipeline project in Bohai Bay. This research shows that, with consideration for the complicated marine environment, existing suspended spans are within allowable length limitations. However, continuing to limit the length of these submarine pipeline spans in the Nanpu oil field will require ongoing attention. 相似文献
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This paper presents analytical and numerical researches on the buckling or collapse of offshore pipelines under external hydrostatic pressure. Firstly the case of homogeneous ring model is investigated followed by a detailed study on corroded rings. The elastic-plastic collapse pressure could be treated as the least root of an elementary function. We prove that collapse pressure is a strictly increasing function of mode number in this paper and present some interesting structures of the roots. Partially corroded ring is parametrized by corrosion depth and angle extent. A comprehensive comparison shows that plasticity should not be neglected when the ring is thick-walled. Moreover, a study on large deflection deformation of 3D cylindrical shells quasi-statically dented under constant external pressure is carried out theoretically and numerically. The buckle propagation pressure is shown to be a meaningful value to normalize external pressure. This paper serves to enhance the understanding of destabilizing effect of external pressure mainly applicable and relevant to subsea offshore industry. 相似文献
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考虑流固耦合时的海底管道悬跨段非线性动力分析 总被引：6，自引：0，他引：6
通过对管道的涡激振动试验,提出了考虑流固耦合的非线性涡激升力表达式,并用该式进行了海底管线悬跨段非线性动力响应时程分析。对考虑流固耦合与未考虑流固耦合情况下得到的管道动力响应时程进行对比,算例表明:当管外流场流速与管道顺流向振动速度值较接近时,不考虑流固耦合时的计算结果明显小于考虑流固耦合时的计算结果。分析认为,在管外流场流速与管道顺流向振动速度值较接近的情况下,管道的涡激振动计算宜采用非线性涡激力模型。 相似文献
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地震条件下海底双层油气管线的工作理论、强度标准和损伤评价 总被引：1，自引：0，他引：1
我国渤海湾是地震多发地区 ,该地区的海底输油管线随时都面临地震的威胁。地震成为渤海输油管线必要的设计条件 ,地震载荷是在役管线安全风险评估必须包括的环境载荷。本文综述了国内外在管线抗震设计及相关研究、双层油气管线的工作理论、强度标准与损伤评判等方面的研究工作 ,对我国制定地震条件下海底管线的评估计算方法、管线的抗震设计准则以及地震灾害的防治与风险分析具有一定的参考价值 相似文献
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- With the rapid development of the offshore oil industries, submarine oil / gas pipelines have been widely used. Under the complicated submarine environmental conditions, the dynamic characteristics of pipelines show some new features due to the existence of both internal and external flows. The paper is intended to investigate the vortex-induced vibration of the suspended pipeline span exposed to submarine steady flow. Especially, the effects of the flow inside the pipeline are taken into account. Its influences on the amplitude of pipeline response, and then on the fatigue life, are given in terms of the velocity of the internal flow. 相似文献
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Jingbo Su Jianfeng Li Ruihu Zhu Wanggen Qin Qiu Zhai 《Marine Georesources & Geotechnology》2016,34(7):689-702
To assess the impact of pile driving on adjacent submarine pipelines during the reconstruction of a pier berth, the local damage model of submarine pipelines is established to explore the safety thresholds of the particle peak velocity and horizontal displacement. The results are analyzed and adjusted by the existing standards and the corresponding literatures. Then, a three-dimensional numerical model is presented to assess the feasibility of the construction of piles by the obtained safety limits, in which the nonlinear behavior of the soil and stress–seepage coupling analysis are considered. After the construction, the safety of submarine pipelines is rechecked by the measured value of the particle peak velocity and horizontal displacement. Meanwhile, the propagation law of vibration, the horizontal displacement of underground soil, and the pore pressure during pile driving are explored. The results indicate that the construction of piles of 2# mooring pier did not cause damage to adjacent submarine pipelines. However, the construction of piles of 1# mooring pier which is nearer may cause damage to submarine pipelines. 相似文献
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The stability of submarine pipelines has been extensively studied by coastal engineers in recent years. Seismic-induced pore pressure and effective stresses in the saturated porous seabed and pipeline are the main important factors in the analysis of foundation stability around submarine pipelines. The majority research of the seismic-induced dynamic response around an offshore pipeline has been limited to two-dimension cases. In this paper, a three-dimensional finite element model including buried pipeline is established by extending DYNE3WAC. Based on the proposed numerical model, a parametric study is conducted to examine the effects of soil characteristics and pipeline configurations on the seismic-induced soil response around offshore pipelines. 相似文献