The two mooring dolphin concept for exposed tanker terminals

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.     

The Behaviour of LNG Carrier Moored to a Jetty Exposed to Waves,Swell,Unsteady Wind and Current

—Most terminals for tankers are piers and sea islands,while other types include single pointmoorings and multiple-buoy moorings.The LNG and LPG carrier moored to the jetty is a very commonterminal for transfer of gas in open seas.It is important to estimate the motions and line tensions of theLNG carrier when it moors to a jetty in metocean environment.Normally,the motions of the LNG carrierwould be restricted by the loading arm,which is connected to LNG carrier＇s manifold.An example of125,000m~3 LNG carrier moored to a jetty exposed to a set of environment conditions is given.Amathematical model which is based on the equations of motion in the time domain is used to the analysisof LNG moored to an offshore jetty exposed to waves,swell,wind and current.By means of a time do-main computer program TERMSIM computations are carried out to determine and optimize the lay-outand/or orientation of the jetty and mooring gear in terms of forces in mooring lines and fenders and theenvelope of motions of the loadi     

旅游码头与渔港码头结合之思考

为了打造帆船之都,促进青岛旅游业和旅游经济的发展,提出了利用休渔期,选择安全性能好的渔船和经过专门培训的渔民搞海上旅游观光、垂钓并发展渔村餐饮业,以解决渔民增收和生活问题,使旅游码头和渔港码头优势互补,共同发展,为青岛旅游业开辟另一条新路。     

大万山波浪能试验场泊位间水动力影响分析

当前我国近海海域属稀缺资源,波浪能试验场建设须通过合理布局各测试泊位,在保证试验场各泊位可同时正常开展测试工作的前提下,尽量减小用海面积。拉近试验泊位距离,是减小用海面积的直接手段,但在此过程中,必须保证在试验场场址海域水动力环境下,泊位接入测试波浪能装置后,其之间的水动力影响在可接受的范围内。以大万山波浪能试验场泊位设计为例,介绍一种有效的泊位间水动力影响分析方法。方法采用自主开发的二维Boussinesq波浪模型,开展水动力影响分析工作,同时引入相对波高比概念,对泊位接入装置后影响距离和影响面积进行了定量的分析。文中研究得出的分析方法,可用于判定泊位布局设计的合理性。     

Dynamics of a moored barge under regular and random waves

Developments in the study of wave forces and construction techniques in deep water by the offshore oil industry have increased the use of marine terminals at deep water locations. A thorough understanding of moored ship dynamics when subjected to waves, wind and current combined with the use of flexible mooring lines would help to design berthing terminals for exposed areas. In this paper, the three dimensional problem of wave interactions with a barge moored to a single point is dealt with, based on the finite element method. The effect of flexibility of the mooring line and the point of mooring on the response of the barge as well as the mooring line tension is investigated. The paper compares the numerical results with model tests carried out on a barge moored to a fixed support under regular and random waves in head sea. The effect of stiffness of the mooring line on the barge response for different mooring points is discussed, which would be useful for the designers. The effect of viscous damping is also considered. The analytical results are in good agreement with the experimental results in both regular and random waves.     

大型泊位设计中的水流问题——以宝钢马迹山港为例

本文以宝钢马迹山２５万吨级矿石中转港码头设计中所遇到的水流问题为例,通过对研究水域的水流性质以及泊位、船舶、水流三者之间关系的初步分析,认为水流尽管与风、浪一样不致船舶结构破坏,但一定时段内却可能对其靠泊造成困难,而水流作用于系泊中船舶并传递给码头结构物的荷载,以及水流与波浪相互作用使得波流要素改变则是设计中必需考虑的。最后,作者对港口设计和运作提出建议,以期相类似水深流急地区建设大型泊位时能有所借鉴。     

不规则波作用下的船舶撞击作用

随着波谱理论研究的发展,各种海工结构及船舶的荷载及其内力分析也日趋应用不规则波的计算方法。目前对于外海码头在波浪作用下的船舶撞击荷载还应用规则波的研究方法,对其应用不规则波分析方法的途径以及在考虑波谱作用后会有怎样的结果等问题目前还较少研究。本文试图对此问题进行初步的分析。     

THE EQUAL PROBABILISTIC COMBINATION BETWEEN SEA STATE AND RESPONSE OF STRUCTURE

Combination of a fixed design wave height with various wave periods may exert quite different wave loads on ocean structure. The response of structure induced by mild sea state may be larger than that by severe sea state because the frequency of the spectral peak for mild sea state is near to the natural frequency of structure. Thus it is necessary to investigate the worst combination between wave height and period, and also the critical combination between sea state and response for any design criteria. This paper presents a new combinative mode of wave height and period for equal return period. The selections of original design wave height and the critical combination of sea state with response for equal probability are also discussed.     

海上中距离跨海高程传递方法比较

远离岸线的中距离(30~50 km)海域缺少测绘基础资料,高程传递尚未形成相应的作业体系。为满足海上工程建设的精度要求,采用同步验潮平均海面传递法、GNSS/水准传递法以及DTU18全球平均海面模型传递法,在山东省半封闭海域与开阔海域进行了中距离海上高程传递实验。实验结果表明,15天同步验潮平均海面传递法与GNSS/水准法的精度相当(厘米级),与DTU18全球平均海面模型传递法进行直接传递的差异在15 cm内,可为不同测绘基础条件下海上风电高程基准传递提供作业参考。     

在开敞海域,淤泥底质建造板桩结构码头的实践与分析

本文主要以黄河海港建港的经验与实践,介绍板桩结构码头的设计特性和施工过程的技术措施,提供了在开敞海域下淤泥底质建港的实践经验和应用前景。     

Experimental and numerical investigations of monopile ringing in irregular finite-depth water waves

In storm conditions, nonlinear wave loads on monopile offshore wind turbines can induce resonant ringing-type responses. Efficient, validated methods which capture such events in irregular waves in intermediate or shallow water depth conditions are needed for design. Dedicated experiments and numerical studies were performed toward this goal. The extensive experimental campaign at 1:48 scale was carried out for Statoil related to the development of the Dudgeon wind farm, and included both a rigid model and a flexible, pitching-type, single degree-of-freedom model. Twenty 3-hour duration realizations for 4 sea states and 2 water depths were tested for each model. A high level of repeatability in ringing events was observed. Uncertainties in the experimental results were critically examined. The stochastic variation in the 3-hour maximum bending moment at the sea bed was significantly larger than the random variation in repetition tests, and highlighted the need for a good statistical basis in design. Numerical simulations using a beam element model with a modified Morison wave load model and second order wave kinematics gave reasonable prediction of the ringing response of the flexible model, and of the measured excitation forces on the rigid model in the absence of slamming. The numerical model was also used to investigate the sensitivity of the responses with respect to damping and natural period. A simple single degree-of-freedom model was shown to behave similarly to a fully flexible model when considering changes in natural frequency and damping.     

Optimal Stiffness for Flexible Connectors on A Mobile Offshore Base at Rough Sea States

This paper investigates a simplified method to determine the optimal stiffness of flexible connectors on a mobile offshore base (MOB) during the preliminary design stage. A three-module numerical model of an MOB was used as a case study. Numerous constraint forces and relative displacements for the connectors at rough sea states with different wave angles were utilized to determine the optimized stiffness of the flexible connectors. The range of optimal stiffnesses for the connectors was obtained based on the combination and intersection of the optimized stiffness results, and the implementation steps were elaborated in detail. The percentage reductions of the optimized and optimal stiffness of the flexible connector were determined to quantitatively evaluate the decreases of the constraint force and relative displacement of the connectors compared with those calculated by using the original range of the connector stiffnesses. The results indicate the accuracy and feasibility of this method for determining the optimal stiffness of the flexible connectors and demonstrate the rationality and practicability of the optimal stiffness results. The research ideas, calculation process, and solutions for the optimal stiffness of the flexible connectors of an MOB in this paper can provide valuable technical support for the design of the connectors in similar semisubmersible floating structures.     

A simplified method to downscale wave dynamics on vertical breakwaters

A coastal structure is usually designed with the final objective to guarantee its functionality and stability throughout its life cycle. Regarding stability, the three main failure modes are sliding, overturning and failure of the foundations. To accomplish the design objectives, a design sea state is usually used when calculating the loads and scour around the structure. This design sea state corresponds to a certain sea state with specific return period values of a significant wave height. However, the combination of different simultaneous sea state parameters can produce other critical situations compromising the stability of the structure which then require the calculation of long time series of wave forces corresponding to long-term historical wave situations. Moreover, a design force associated to a certain return period can be defined from the time series of the stability parameters. The most accurate techniques which can be used to estimate structure stability are based on numerical and physical models, but these are very time consuming and the calculation of long time series is therefore unfeasible. Here, we propose a hybrid methodology to transform wave conditions into wave forces acting upon vertical structures and scour around it. The methodology consists of a selection of a subset of sea states representative of wave climate at the structure location, using a maximum dissimilarity algorithm, The wave forces acting upon the structure and scour around it, for the wave situations selected, are then estimated as is the reconstruction of the calculated parameters corresponding to historical sea states using an interpolation technique based on radial basis function. The validation of the results, through a direct comparison between reconstructed series and analytically (semi-empirical formulations) calculated ones, confirms the ability of the developed methodology to reconstruct time series of stability parameters on vertical breakwaters. This methodology allows its application to numerical and physical models.     

海洋石油钻井平台工程地质条件评价技术研究

海洋石油钻井平台是海洋油气勘探开发的重要手段,其安全就位和稳定施工,与井场区海底的工程地质条件密切相关。就事关平台安全的工程地质条件预测评价技术作了研究,评价预测了与自升式钻井平台稳定作业有关的软弱下卧地层的穿插和持力、海底斜坡条件下工程地质层稳定性、半潜式钻井平台的锚固力以及不同底质条件下海底底流的冲蚀。推荐了实践有效的半经验计算公式,为海洋石油钻井平台井场工程地质条件的稳定评价提供参考。     

The significance of earthquake-induced dynamic forces in coastal structures design

The dynamic forces of sea water and backfill soil acting on coastal embankments and the hydrodynamic forces on offshore breakwaters have been analyzed using a finite-difference scheme. A non-horizontal sea bottom is considered in the analysis. Both rigid and flexible embankments are included in the study. For a coastal embankment, the hydrodynamic pressure of sea water acting on the embankment face significantly increases as the slope of the sea bottom increases. On the other side of the embankment, the pore pressure and the interaction force between the soil and fluid will augment significantly when the backfill soil is compressed during earthquakes. When the sea-embankment-backfill soil interaction is included, the dynamic forces acting on a flexible embankment are much larger than those on a rigid one. The comparison of evaluating the sliding of a cassion in a case study of SPM by a conventional analysis and the present seismic analysis was made. The earthquake-induced dynamic pressures on both sides of the embankment (or breakwater) could be much larger than the force generated by the storm surge. The hydrodynamic (or seismic) analysis incorporating the effect of an earthquake should be included in the coastal embankment or offshore breakwater design, especially for the area with active earthquakes.     

渔港卸鱼码头合理泊位利用率研究

本文用计算机模拟方法计算出渔港缺卸鱼码头合理泊位利用率,可供渔港规划时参考。     

深海腐蚀检测用水密电子舱设计

设计了一种可在300 m 水深条件下进行腐蚀电化学在线检测作业的水密电子舱, 它主要由耐压水密壳体以及集成在壳体外部的插接件式电极系统和多孔屏蔽罩组成。耐压壳体由圆柱形筒体和加强型平盖构成, 满足设计条件下的强度、密封、防腐要求。三电极系统采用水密接插件式设计, 安装在加强型平盖上; 电极系统与外部多孔罩组成开放屏蔽式电解池, 可在水下进行在线电化学测试。     

某港口专用粮食泊位装卸工艺设计及设备选型介绍

以一个典型设计为例,介绍了我国沿海港口散粮专业化泊位的装卸工艺流程设计和工艺布置,并对主要设计参数和水平输运、垂直输运、泊位前方和后方等主要装卸工艺设备的选择进行了分析。     

测线布设方向的不同对海底显示的影响

通过对几种典型海底沿不同方向布设测线所得到的拟合海底与原海底进行比较,发现测线布设方向的不同对海底显示的影响可归结为两种效应：平滑效应与伸缩效应。同时指出：对非线性平坦海底,沿梯度总方向布设测线、对于海底闭包按极坐标法布设测线可以很好地消除这两种效应的影响,从而达到完善海底显示的目的。实例分析结果验证了结论的正确性,该法可用于实际作业提高测深线布设对海底显示的准确度,同时直接构成海道测量智能设计系统的测深线自动布设建模。