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1.
远海浮式结构物与供应船旁靠系泊特性研究 总被引：1，自引：0，他引：1
针对远海浮式结构物与供应船进行旁靠作业时,水动力干扰、两船的相对运动、旁靠系缆系统和护舷系统的受力特征等问题开展研究。建立各船的有限元模型,设计出两船旁靠连接缆系统,选取合适的系泊缆和护舷参数。研究表明:浮式结构物和供应船的横荡、纵荡方向存在一定的同步性或跟随性,幅值相差不大,其它方向的运动并不存在明显的同步特征;供应船的各自由度运动幅值均比浮式结构物偏大;旁靠护舷的受力时历出现了明显的低频效应,说明护舷的受力较大程度上受船体低频慢漂运动的影响;浮式结构物对供应船的水动力干扰较大,当浮式结构物在供应船的上风位置时,表现为屏蔽效应,供应船的运动较小;在其背风位置时,运动加剧,出现多次共振、峰值放大现象,供应船对浮式结构物的水动力性能几乎无影响,因此,供应船从浮式结构物的下风口一侧靠泊作业将更有利于船舶的安全性能。这些研究结论可为实际工程操作提供参考。 相似文献
2.
It has been argued that a major shortcoming in the International Maritime Organization (IMO) Interim Guidelines for Approval of Alternative Methods of Design and Construction of Oil Tankers in Collision and Grounding is that grounding and collision damages normalized by the main dimensions of the ship have the same probability density distributions regardless of a particular structural design and ship size.The present paper explores analytical methods for assessing the overall effect of structural design on the damage distributions in accidental grounding and collisions. The results are expressed in simple expressions involving structural dimensions and the building material of the ships. The study shows that the density distribution for collision and grounding damages normalized by the main dimensions of the ship depends on the size of the ship. A larger ship has a higher probability of a larger relative damage length than that of a smaller ship in grounding damage. On the other hand, the damages to the side structure caused by ship collisions are found to be relatively smaller for large ships.The main conclusion is that the existing IMO damage distributions will severely underestimate the grounding damages to the bottom structure of larger vessels and to a lesser extent overestimate collision damages to the side structure of the hull. 相似文献
3.
随着船舶大型化和港口建设深水化发展,外海不同周期波浪作用下大型系泊船泊稳问题与小型系泊船相比出现了新的特点。为此,利用数值模型方法研究了在不同入射角度和周期的涌浪作用下港内大型系泊船的水动力响应,针对系泊船的泊稳情况探讨了船舶的运动规律和运动特性。研究发现,在涌浪周期较大的情况下,限定波高的泊稳标准不足以用来确定系泊船的正常作业条件,港内泊船的水平运动（纵荡、横荡和艏摇）极易超出运动标准值并影响装卸作业效率,并且船舶的水平运动表现出主要由次重力波主导的低频运动特性,而垂直运动（垂荡、横摇和纵摇）表现出主要由短波主导的波频运动特性。 相似文献
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At present the position keeping of ocean going vessels, offshore service vessels, etc., is performed by mooring systems to resist external forces under severe environments consisting of wave, current and wind. A variety of mooring systems are employed depending on the shape, principal dimensions, etc., of the vessels in addition to the surrounding conditions of the water areas. Ocean going ships are moored to the shore structures through a multiple system of moorings. The determination of the forces in the cables is essential for the design of moorings and the berthing structures. However, the ships engaged for offshore operations are moored by the mooring cables, spread around the ships with the other ends of the moorings anchored to the sea bed. In these cases, the required number and length of cables can be arrived for a given ship of known dimensions and environmental conditions. With the increased overall dimensions of the vessels, it is necessary to conduct a study on enhancing the accuracy in estimating the mooring system performance. Hence, the present work is mainly intended to carry out model tests to investigate the behaviour of moored ships that are subjected to wave and current loadings. These model experiments were conducted in a 30 m × 2 m × 1 m wave-current flume at the Ocean Engineering Centre, Indian Institute of Technology, Madras. 相似文献
6.
《中国海洋工程》2020,(4)
The study of mooring forces is an important issue in marine engineering and offshore structures. Although being widely applied in mooring system, numerical simulations suffer from difficulties in their multivariate and nonlinear modeling. Data-driven model is employed in this paper to predict the mooring forces in different lines, which is a new attempt to study the mooring forces. The height and period of regular wave, length of berth, ship load, draft and rolling period are considered as potential influencing factors. Input variables are determined using mutual information(MI) and principal component analysis(PCA), and imported to an artificial neural network(NN) model for prediction. With study case of 200 and 300 thousand tons ships experimental data obtained in Dalian University of Technology, MI is found to be more appropriate to provide effective input variables than PCA. Although the three factors regarding ship characteristics are highly correlated, it is recommended to input all of them to the NN model.The accuracy of predicting aft spring line force attains as high as 91.2%. The present paper demonstrates the feasibility of MI-NN model in mapping the mooring forces and their influencing factors. 相似文献
7.
The effects of free-surface waves on the floating structures are of great importance in the offshore industry. Among the six degrees of motions of a surface ship the absence of restoring forces in surge, sway and yaw led to critical situations for moored ships in the recent times. The order of forces in horizontal plane and their exciting frequencies are matters of interest. The resonance with the presence of moored chains led to many accidents in the recent past. The lines in dry conditions may not give good damping and in wet condition they may trigger the system to chaotic motions and jumps. Two different loading conditions of a container ship model are tested with waves in laboratory conditions in two different drafts. The mooring lines are chosen as per scale law and the energy under the response spectrum is determined from the plots. The results give new insights into the movement of a berthed ships subjected to waves. Response of the moored ship to different loading conditions in different water depths are discussed in this paper. The paper gives the order of energy due to first-order and slowly varying movement of a berthed container model in a towing tank. 相似文献
8.
The conventional design for a tanker terminal provides for two or more mooring dolphins on each side of the breasting dolphins. Head and stern lines are attached to the outer mooring dolphins and breast lines to the inner mooring dolphins. In exposed locations, the expense of construction may be significantly reduced if a way can be found to reduce the number of mooring dolphins required for the safe mooring of ships at a fixed berth.This paper, based on studies for a proposed terminal for tankers from 25,000 to 100,000 DWT in the Bay of Fundy in Eastern Canada, discusses the possibility of reducing the total number of mooring dolphins from four to two. Results of a static analysis of mooring loads due to wind and current and a hydraulic model test for mooring loads due to waves are presented.Operational aspects of the two mooring dolphin layout are discussed. It is concluded that the two mooring dolphin concept is an efficient mooring arrangement which will reduce the cost of fixed berth terminals. It is noted, however, that many of the smaller, older tankers in the world fleet do not have adequate mooring equipment to use such a berth and it is recommended that the necessary change in deck equipment be made to allow for such an arrangement. It is also recommended that ship personnel acquaint themselves with mooring procedures using breast and spring lines alone. 相似文献
9.
This paper presents the research on the external mechanism of collision characters for a SPAR platform. The collision characters of SPAR platform have not attracted so much attention as that of ships in the past, because short of this kind of collision accidents reported. But with the increasing number of SPAR platforms in the world, the possibility of such kind of accident also increases. Therefore, it is necessary to master the character of SPAR collision. Model test technique is employed to study the external mechanism. The collision scenario is a ship colliding with a SPAR platform moored in the site with 1500 meters water depth. The striking ship hits the SPAR platform on the hard tank near water surface in its longitudinal direction. The specifics of the SPAR＇s motions and the tension forces of the mooring lines are collected to summarize the hydrodynamic characters in the collision scenario. It is found that the maximal displacements and the maximal pitch angles of the SPAR platform, and the maximal tension forces of mooring lines are all linearly proportional to the initial velocity of the striking ship basically. Mooring lines play elastic roles in the collision course. 相似文献
10.
There is a need to obtain the hydrologic data including ocean current,wave,temperature and so on in the South China Sea.A new profiling instrument which does not suffer from the damage due to nature forces or incidents caused by passing ships,is under development to acquire data from this area.This device is based on a taut single point mid-water mooring system.It incorporates a small,instrumented vertically profiling float attached via an electromechanical cable to a winch integral with the main subsurface flotation.On a pre-set schedule,the instrument float with sensors is winched up to the surface if there is no ship passing by,which is defined by an on-board miniature sonar.And it can be immediately winched down to a certain depth if the sonar sensor finds something is coming.Since,because of logistics,the area can only be visited once for a long time and a minimum of 10 times per day profiles are desired,energy demands are severe.To respond to these concerns,the system has been designed to conserve a substantial portion of the potential energy lost during the ascent phase of each profile and subsequently use this energy to pull the instrument down.Compared with the previous single-point layered measuring mode,it is advanced and economica1.At last the paper introduces the test in the South China Sea. 相似文献
11.
During the past 30 years there has been a steady growth in the size and number of ships that use the Strait of Istanbul (Bosporus) which is one of the most hazardous, crowded, difficult and potentially dangerous waterways in the world. There have been over 200 accidents over the past decade resulting in loss of life and serious damage to the environment. This paper presents the results of a real-time ship manoeuvring simulation study investigating the manoeuvring performance of large tankers in the Bosporus. The study was conducted with a ship manoeuvring simulator which is capable of subjecting a given hull form to any combination of environmental conditions, i.e. wind, current and wave drift forces. The results indicate that when realistic environmental conditions are taken into account the size of ships which can navigate safely in compliance with the traffic separation lanes is limited. 相似文献
12.
海上钻井平台由于工作地点经常发生变化,工作环境条件随之改变,锚泊抛锚方式就要相应更改。本文针对深海半潜平台及其悬链线式系泊定位系统,运用平台与锚链耦合运动时域分析方法,对其水动力性能进行探索,并提出一种运用模糊算法计算平台抛锚方式优化设计方法,此方法可使钻井平台在风暴自存工况和钻井工作工况下更快更好地找到最佳抛锚方式。以一典型的半潜式钻井平台为例进行数值模拟,结果表明本文提出的方法是可行的,能够很方便地找到比较好的抛锚方式来满足相关要求。这种锚泊优化设计方法可为平台及其系泊系统设计提供参考。 相似文献
13.
平台坠物、船舶抛锚等第三方活动引起的冲击损伤是近海管道失效的主要原因,时刻威胁中国海洋油气开发系统的安全性。为保障近海油气管道安全运行,围绕冲击荷载作用下管道损伤及失效评估这一中心问题,从管道损伤机理研究、含冲击损伤管道安全评估、管道工程项目风险评估3个方面总结了国内外研究发展现状,明确了影响结构安全的关键问题,并对未来研究工作提出建议。挖沟埋深为管道防护冲击损伤的有效手段,土体强度是防护效果关键因素,应重点关注土体强度空间变异性问题;管道冲击损伤主要为平滑凹陷和弯折凹陷,对于后者应进一步确定其在内压荷载下的剩余强度及疲劳强度;风险评估中失效判据对于结果有显著影响,需构建考虑多种安全性评估准则的失效判据体系。 相似文献
14.
非通航孔桥墩自适应拦截网防撞装置实船拦截试验与水动力计算 总被引：1，自引：0，他引：1
针对非通航孔桥墩,研发了一种自适应拦截网防船舶撞击装置,主要由系泊大浮体、系泊锚链和固定锚、自适应小浮筒、拦截网、恒阻力缆绳以及触发钢索所组成。阐述了该防撞装置设计原理,即偏航船舶撞击该防撞装置,小浮筒会带动拦截网自适应地从水平状态竖起展开,包裹住来撞船首,再通过相连浮体的运动阻力和恒阻力缆绳来吸收船舶动能,拦截住船舶,保护非通航孔桥墩安全。随后介绍在福建平潭海峡大桥引桥附近海域实施的实船撞击自适应拦截网防撞装置的大型试验,试验结果显示:自适应拦截网成功升起,船舶被安全拦截,从而实验证实了设计原理与设计方案的可行性和可靠性。最后,采用大型水动力分析软件AQWA对防撞装置拦截船舶过程进行数值模拟,模拟结果与实验结果基本一致,说明了数值仿真具有较好的计算精度和可靠性,能够为该防撞装置的结构设计与优化提供重要的参考。 相似文献
15.
Kelvin wake is one of the common wakes generated by moving ships and contains rich information about ships. In this paper, free wave elevations of Kelvin wake are calculated based on the Michell thin ship theory combined with a point source perturbation model. The probability density function of sea surface slopes is introduced to calculate the specular reflection of sunlight and skylight and the refraction of scattered light underwater. Satellite-detected Kelvin wakes are then simulated by adding surface specular reflectance and water-leaving reflectance. Simulation results agree well with satellite measurements. The specular reflection of sunlight is the decisive factor affecting the features of Kelvin wakes according to the simulation results. The main factors that influence the specular reflection of sunlight, such as the incident direction and observation direction, ship parameters, and background environment, are discussed. This study is helpful for wake detection and provides a preliminary theoretical method for the retrieval of ship information. 相似文献
16.
为克服典型情景模拟法的缺陷,综合考虑船舶溢油发生的随机性、海洋水动力和风场的不确定性以及环境资源的敏感性,提出基于随机情景模拟的船舶溢油危害后果定量评价方法。通过随机情景模拟和网格化统计得到敏感区的溢油污染概率和最快到达时间,结合环境敏感指数和溢油量等参数计算综合溢油危害指数,并将其作为溢油危害后果定量评价指标。结果表明:台湾海峡北部水域不同季节发生船舶溢油的危害后果大小依次为夏季(27.8)秋季(25.5)春季(21.1)冬季(16.2),夏季溢油事故对牛山岛保护区的污染概率和危害后果相对最大(P=60%,Ck=41.2),达到较高级别;其他季节东甲列岛保护区的溢油污染概率和危害指数均为最高。随机情景模拟能够弥补事故情景,为评价船舶溢油危害后果风险提供一种新方法。 相似文献
17.
Ship berthing and mooring monitoring system by using pneumatic-type fenders has been proposed. This system consists of present berth monitoring system including a mooring line load monitoring system, and a fender load monitoring system. The fender loads such as fender deflection and reaction force are calculated by measuring inner air pressure of the pneumatic fenders, which have unique characteristics in performance. Furthermore both loads for the mooring lines and the fenders can be used to estimate moored ship motions simultaneously. Total ship monitoring system at jetty can be achieved and contributes safe ship berthing and mooring. 相似文献
18.
旁靠带缆作业是实现海上补给、模块吊运、原油外输等运转的常用方式,针对浮式平台与两艘供应船以旁靠方式作业涉及的关键特征进行水池模型试验研究,阐述了旁靠带缆系统和护舷设备的属性和需遵循的规范衡准,深入分析旁靠系缆的张力、护舷的挤压力、船体之间的相对运动特征随有效波高和波浪入射角度等环境参数的变化规律,确定了适用于多船旁靠作业的海况条件。研究表明:波浪能量随有效波高的增大呈现非线性增大趋势,是影响旁靠作业窗口期的主要外部因素,而波浪入射角度对旁靠作业的影响程度与海况有较大关系;三船在纵荡、横荡以及艏摇方向具有明显的跟随性特点,运动响应的幅值和相位比较接近,浮式平台与供应船之间的相对运动较小,完全可满足作业要求。垂荡、横摇以及纵摇这三个波频方向,各船的运动并不同步,相对运动大,是影响多船旁靠作业窗口期的主要因素;有效波高为2.5 m的海况条件可满足多船旁靠要求。相关结论为实际的工程操作提供参考。 相似文献
19.
Fish cages in the open sea are exposed to cycle loads due to irregular wave climate during their service life, and thus the fatigue reliability assessment of mooring system should be conducted to ensure the safe operation. The aim of this study is to evaluate the fatigue failure probability of mooring system for fish cage. Numerical simulation of net cage in random waves is performed and the time dependent approach is applied to conduct the fatigue reliability analysis of shackle chains based on S-N curve method. The sensitivity analysis of fatigue reliability of mooring line to the uncertainty of random variables in the fatigue limit state is conducted. In addition, the system reliability for mooring system is analyzed and the effect of the initial pretension and safety factor on system reliability is investigated. The results indicate that a case without the initial pretension on anchor lines is helpful to decrease the failure probability of mooring system and the safety factor of mooring lines in the current regulation is conservative for the system reliability against fatigue damage. 相似文献