基于拖曳锚轨迹方程的拖曳锚系泊优化分析

拖曳锚系泊作为目前海洋工程使用最为广泛的系泊方式，因其较低的制造和安装成本使其成为小型浮式平台系泊方式的首选。目前拖曳式系泊设计大多根据以往工程经验进行选择设计，由于经验设计中并没过多的泥面表面及以下锚链安装信息，因此在设计之初很难对系泊材料用量准确计算。不同重量的拖曳锚在同样的嵌深和同样的锚倾角条件下，所能提供的系泊力大不相同。同时，不同重量的拖曳锚的在相同土壤条件下拖曳嵌入轨迹不同，因而最大埋深不同。上述两方面原因导致不同重量的拖曳锚提供的系泊力不一样。因此，需要达到同样的系泊效果，泥线以下反悬链线和卧底链的长度在不同重量锚的系泊系统中是不同的。参照系泊成本各个分项在其生命周期各阶段的占比，材料制造成本与安装成本占据系泊成本的大部分，且安装成本往往正比于材料成本。因此降低系泊锚链的材料成本对整个系泊系统的成本降低起到了巨大的优化作用。通过结合拖曳锚的极限平衡法拖曳轨迹理论方程，以不同重量的拖曳锚在粘性土壤中的不同拖曳距离下提供额定系泊力时所需要的材料重量为系泊成本评价依据，从而得到浮式结构物系泊系统的一种设计优化方法。     

洋流作用下悬浮隧道动力学行为试验研究

本研究根据相似准则和试验条件设计试验模型。在试验模拟的1节悬浮隧道管段上分别布置2组和3组锚索支撑,测试在不同流速条件下,悬浮隧道管体结构的环向应变、轴向应变及张力腿锚索的轴力。根据试验结果,初步分析悬浮隧道应力的空间分布特征和张力腿的轴力情况;给出在相同环境条件下,张力腿锚索数量对结构应力的影响、洋流速度对悬浮隧道管段结构变形和张力腿轴力的影响关系等。     

上海金茂大厦地锚试验

金茂大厦地下结构支护方案之一是采用地锚作为地下连续墙的锚固结构,为了确定设计参数,验证地锚施工的可行性,开展了一系列科学研究,通过直锚和斜锚的施工工艺现场试验,达到了预期效果。抗拔力达到了设计初定的300t指标要求,为地锚设计与施工提供了依据。     

Simulation of torpedo anchor set-up

Torpedo anchors are used for station keeping of floating offshore platforms and fixing risers to the seabed in deep water. Their main benefit over other anchors is reduction in anchor installation cost via free falling in the water. A torpedo anchor has a steel cylindrical shaft with a conical tip and is ballasted in order to deepen the soil penetration and increase the anchor holding capacity. In order to address the installation effects on the soil strength and consequently the anchor pull-out capacity, first reconsolidation (set-up) of soil next to the anchor after installation is studied by a finite-element (FE) analysis of coupled deformation and fluid flow in porous media. The results of the set-up analysis indicate the rate of dissipation of excess pore-water pressure and soil-strength recovery. These are important considerations in predicting the anchor pull-out capacity at different times after installation. In the absence of a documented complete set of installation and set-up tests, the results are validated qualitatively using available albeit limited field test data.     

The uplift capacity of single-plate helical pile in shallow dense sand including the influence of installation

The helical pile has been used to resist the tension for a long time. However, the prediction of the uplift capacity of helical piles including the influence of installation is still a challenge in design. Based on the change in stress according to Mohr-Coulomb failure criterion, a simple theoretical method has been developed, which can calculate the uplift capacity of shallow pre-embedded circular plate anchors and the uplift capacity of helical piles installed by torque and compression. In order to analyse the influence of installation process of a single-plate helical pile on its uplift capacity and verify the theoretical model, a series of model tests have been conducted in dense saturated sand. The single-plate helical piles with different out diameters of helixes have been installed with different installation speeds, and then, the single-plate helical piles have been moved up monotonically. The test results show that the installation speed and the size of the out diameter of the helix have significant influence on the uplift capacity of the helical piles, and the results of the theoretical method have a good fit with the test results. Using this simple theoretical method, the designer can easily predict the uplift capacities of helical piles, which includes the influence of installation.     

锚链直径对船舶锚泊能力的影响

从减轻船总体负担、采用链径更小的海洋系泊链的设计需求出发,以单个链环为微元对锚链在锚泊状态所形成悬链线方程进行推导,建立锚链在典型锚泊状态下的悬链线方程,并以此为基础完成不同链径锚链在抛锚长度、最大可承受环境力、最大抛锚深度等方面的计算分析。结合计算结果和船舶实际使用情况,对采用不同链径锚链的锚泊能力进行综合分析后认为,虽然链径较粗的锚链的理论锚泊能力较强,但若采用霍尔锚等非大抓力锚,或对锚泊水域面积无明确要求、没有在深水中抛锚的特殊需求等,则可以选用链径相对较细的海洋系泊链代替目前规范中规定的电焊锚链。     

基于管道极限承载能力分析的深水S型铺管托管架基本设计研究

S型铺管托管架是铺管系统中的重要装备,起到支撑管道和引导管道入水的作用。其基本设计流程是一个复杂的循环过程,涉及铺管船推进力、张紧器张力、待铺设管道的尺寸和铺设水深等诸多参数的平衡和优选。本文基于下弯段管道在弯曲、拉伸和外压综合荷载作用下的极限承载能力分析,求解了铺管船推进力和张紧器拉力,并以此为边界条件推导了托管架长度的参数公式。以2500米水深铺设12英寸管道为例计算了所需的托管架曲率半径和设计长度,该计算方法可为S型铺管船托管架的基本设计提供参考。     

船舶轻量化T型连接结构设计及强度试验

文章从船舶轻量化的角度出发,提出了一种由复合材料夹芯板和增强泡沫胶接而成的新型T型连接结构,解决了船舶复合材料上层建筑内部壁板之间的连接问题。基于复合材料结构的设计原理和力学特性,设计了T型连接结构的拉伸试验和压缩试验,研究其在不同载况下的极限承载和损伤模式,证明T型连接损伤模式复杂,抗拉能力弱,尤其面板与腹板连接区的胶层是承载薄弱环节;依据试验结果验证数值计算方法,并规划3条技术路径以研究T型连接的抗拉特性,应用数值方法提取对应技术路径的应力和位移特征量,分析T型连接面板与腹板连接区的胶层几何参数对抗拉强度和重量的响应规律,获得连接区胶层几何夹角的建议取值为45°~60°,为复合材料船舶轻量化胶接结构的优化设计和实际应用提供了有益参考。     

内转塔式单点系泊系统敏感性研究

本文以我国南海某条FPSO的内转塔式单点系泊系统为例,研究内转塔式单点系泊的不同参数对于FPSO的运动和系泊张力的影响,确定单点系泊系统不同参数的敏感性.本文从系泊系统材料、系泊系统重量以及系泊缆预张力3个方面考虑其对系泊系统受力及FPSO的运动等设计参数进行敏感性分析.通过分析确定了FPSO的运动和单点系泊系统的动力响应对于系泊系统不同参数的敏感程度.     

Numerical investigations into the influence of geometric configurations on hydrodynamic characteristics of torpedo anchors

Torpedo anchors are an innovative and cost-effective technology in marine foundation engineering; however, there is a lack of systematic and comprehensive studies on the influence of torpedo anchor geometry on its hydrodynamic characteristics, especially the effect of anchor fin configuration on the hydrodynamic characteristics is rarely reported in the existing literature. Therefore, this study investigates the influence of geometric characteristics of both finless and finned torpedo anchors on their terminal velocity, drag coefficient and installation directional stability in water through CFD numerical analysis in a systematical manner. The considered geometric characteristics include the center of gravity position, shape and angle of anchor tip, shaft and fin aspect ratio, fin number, fin thickness, fin shape, fin position and fin area. Based on the obtained numerical results, some practical design recommendations and impact weighting charts of different anchor geometric factors are provided, which enables a quick qualitative and quantitative assessment of torpedo anchors. In addition, a simple weight-based approach for estimation of terminal velocity and drag coefficient of torpedo anchors considering multiple geometric configuration factors is proposed, which may provide some reference and scientific guidance for experimental and engineering design of torpedo anchors.     

20000TEU集装箱船抗扭箱结构的焊接变形预控

抗扭箱作为20000TEU超大型集装箱船的关键结构,由于其组成的板材较厚且与集装箱直接接触,因此需严格控制该结构的面外焊接变形。采用基于固有变形理论的弹性有限元分析,预测抗扭箱的焊接变形,且与实际测量结果比较吻合;通过设计大厚板的非对称X型坡口来控制面外变形,结果表明：采用非对称设计的X型焊接坡口更有利于减小变形,仅需一次翻身、提高生产效率。在不考虑装配间隙时,基于高效的热-弹-塑性有限元计算归纳出超厚板(40mm~85mm)的最佳正反面坡口深度比;而考虑实际生产中的装配间隙时,最佳正反面坡口深度比与板材厚板呈非线性关系。最后将考虑装配间隙时,优化的非对称坡口焊接接头应用到抗扭箱结构中,面外焊接变形减小明显,有利于指导船厂的实际生产。     

Centrifuge modelling of a combined pile-type anchor subjected to general inclined loading

One of the main challenges associated with anchoring offshore platforms is the logistic needed to install them in deep water. The growing need for high capacity anchors has prompted the development of new systems where the feasibility of transporting them out to sea is a crucial consideration. With respect to torpedo piles used by Petrobras in Brazil, new platforms installed in deep water required robust anchoring systems, and a cluster of small torpedoes was considered instead of one large torpedo. However, torpedo pile installation is hindered by deep water streams, which can deviate their trajectory during the fall. This is of great concern for the design of torpedo pile clusters because the distance between the piles cannot be controlled during installation. The present study aims to determine the variation in the load capacity of a cluster or array of single piles as a function of the distance between the piles and the load direction after installation on the seabed. To that end, a series of centrifuge tests were carried out on pile clusters installed in loose sand, varying the distance between the piles and the loading direction. The results show considerable interactions between the adjacent piles depending on the load direction and pile spacing. The optimal spacing for maximum cluster efficiency was determined, and comparisons were made with values from the literature for capped pile clusters.     

考虑应变强化效应海底管道极限承载力研究

文章基于线性强化材料模型,推导了轴向拉力作用下海底管道极限弯矩承载力解析解,给出了海底管道在轴向拉力与弯矩载荷同时作用下的极限承载力的近似解,编制了海底管道极限承载力计算程序BCP。通过与实验结果的比对,验证了解析方法的正确性。结论表明考虑应变强化效应的海底管道极限承载力结算结果更为合理,该文可为海底管道的结构强度设计和安全性评价提供一定的参考依据。     

Internalization of port congestion: strategic effect behind shipping line delays and implications for terminal charges and investment

This paper develops a theoretical model to analyze the congestion internalization of the shipping lines, taking into account the ‘knock on’ effect (i.e. the congestion delay passed on from one port-of-call to the next port-of-call). We find that with the presence of the knock-on effect, liners will operate less in terminals, and an increase of a liner’s operation in one terminal will decrease its operation in the other. If the liners are involved in a Stackelberg competition, whether they operate more or less in a terminal under the knock-on effect depends on the comparison between the marginal congestion costs of terminals. Furthermore, we find that the coordinated profit-maximizing terminal charges are higher than both the socially optimal terminal charges and the independent profit-maximizing terminal charges. When the knock-on effect is small, the independent profit-maximizing terminal charges are set at higher levels than the socially optimal terminal charges; but when the knock-on effect is sufficiently large, this relationship may reverse. Besides, the capacity investment rules are the same for welfare-maximizing terminal operator and coordinated profit-maximizing terminal operator, while independent profit-maximizing terminal operators invest less in capacity. The larger the knock-on effect, the larger this discrepancy.     

船舶直流组网电力推进技术发展优势

通过对国内外多型试验船舶建设方案编制论证、参与设计、全程监造并总结多年实际用船经验,分析了几种船型推进系统的优缺点,同时归纳船舶直流组网技术优势与发展潜力,找到国内外在该领域技术差距,为我国未来试验船研制提供参考.     

SPAR平台锚固基础的有限元分析

SPAR平台是目前应用较为广泛的深海石油平台形式之一,其基础形式主要有吸力锚和桩基。运用有限元分析软件Plaxis 3D Foundation,采用了Mohr-Coulomb弹塑性本构模型,选取具有代表性的吸力锚和桩基进行三维有限元分析,得到了吸力锚和桩基的极限承载力,讨论了二者承载力特性的区别及各自的适用条件。     

Tradable emission permit system for urban motorists: The neo-classical standard model revisited

This article deals with the feasibility of a tradable emission permit system (TEPs) for urban motorists. The objective is to develop a new microeconomic theoretical model to reduce urban pollution. We suppose that the city's regulating authority sets up a tradable emission permit system based on the number of kilometres covered by private cars. By the use of a Constant Elasticity of Substitution (CES) function, we determine the equilibrium under an environmental constraint and analyse the effects of a TEPs on social welfare. The aim is to find the optimal quantity of permits leading to the desired environmental objective. The analytical and numerical results of the model show the instrument's feasibility and efficiency. An important variable in the model must be taken into account: the knowledge of environmental damage. This variable will clearly influence the tool's success.     

船舶撞击高架拦阻系统后的位移计算及与试验结果的比较

为了求解船舶撞击高架拦阻系统后的位移,文章以能量守恒定律为基本原理,即重力锚做功与船舶阻力做功之和近似等于船舶初动能,通过编写迭代计算程序,对船舶撞击高架拦阻系统后的运动情况进行了研究。并将理论计算结果与试验数据进行了比较分析。结果表明：船舶撞击高架拦阻系统后位移的理论计算值与实测值间的误差在正负30%以内;船舶正碰撞拦阻系统跨中位置时,位移最大,且位移随着拦阻系统跨度的增大而增大。该理论计算方法及相关结论可以为高架拦阻系统的设计提供重要参考。     

A model for the biaxial dynamic bending of unbonded flexible pipes

An analytical model is given to investigate the behavior of unbonded flexible pipes under biaxial dynamic bending. The stick-slip conditions of each wire are studied in the framework of incremental analysis by an operator splitting of the time step into a stick-state prediction and a slip-state correction step. The tension gradient is calculated using the classical return-mapping algorithm and the obtained tension gradients are integrated numerically to find the axial tension by imposing appropriate boundary conditions. From the axial tension the bending moments with respect to the principal bending axes of the pipe are obtained. Poisson's effect, bending induced tension in the wire, shear deformations of the supporting plastic layer and the changes of the effective torsion and curvature increments of the wire after slip occurs are taken into account in the model. The results of bending moment–curvature relationship from this model are compared with the test data from simple bending and good correlations are found. The comparison of the biaxial bending moment results between this model and the available model also shows good agreement.     

遗传算法在中冷器优化设计中的应用

基于遗传算法对某车载空—空中冷器进行了结构优化设计,完成了优化设计程序,得到了中冷器芯体结构的优化方案,使优化后的中冷器散热能力在理论上最大提高了19.3%。通过风洞试验对其进行验证,试验结果表明:尽管存在误差,但理论计算总体与试验结果吻合良好,为同类中冷器的优化提供了参考。