共查询到20条相似文献，搜索用时 990 毫秒
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The impact of dropped anchor on submarine photoelectric composite cables may possibly cause electrical faults, i.e. electricity and optical signal transmission failure. In order to study the impact capacity and structural impact failure mechanism, a test setup is designed originally to examine the structural and functional integrity. A detailed finite element model (FEM) is created, considering material nonlinearity and component interaction. A parametric analysis has been performed to predict the deformation of components and impact forces, under different impact velocities and collision directions. Relationships between the armor layer indentation rate and that of internal power and optical units are achieved. The impact deformation of internal entities can be evaluated intuitively by armor layer indentation. The proposed experimental and numerical methods are well correlated, suitable to assess the impact capacity of subsea power cables and assist the protection design of subsea power cables in engineering. 相似文献
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The international submarine cable industry is a major component of the global telecommunications system, providing important services and requiring increased levels of protection for the maintenance of global economic and maritime security, broadly defined. An overview is given of the submarine cable industry, including its technological developments, legal aspects, security considerations, and implications for integrated ocean planning and management. In the context of multiple ocean use, submarine cables can cause spatial conflicts with other ocean users, particularly the fishing industry. Issues to be examined include compensation for lost or damaged gear, legal liability for cable damage, and regulation and licensing of cables on the seabed of the continental shelf and the high seas. Recent industry-to-industry agreements and programs for compensation to fishers in the USA and Canada are significant advancements in the implementation of integrated approaches to ocean management and planning. The development of transparent and stable interdepartmental processes for the coordinated planning, management and regulation of submarine cables is required for national EEZs. The regulation of international cable industry practices must be harmonized with national management approaches. 相似文献
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Umbilical cable is a kind of integrated subsea cable widely used in the exploration and exploitation of oil and gas field. The severe ocean environment makes great challenges to umbilical maintenance and repair work. Damaged umbilical is usually recovered for the regular operation of the offshore production system. Analysis on cables in essence is a two-point boundary problem. The tension load at the mudline must be known first, and then the recovery load and recovery angle on the vessel can be solved by use of catenary equation. The recovery analysis also involves umbilical-soil interaction and becomes more complicated. Calculation methods for recovery load of the exposed and buried umbilical are established and the relationship between the position of touch down point and the recovery load as well as the recovery angle and recovery load are analyzed. The analysis results provide a theoretical reference for offshore on-deck operation. 相似文献
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在国内外深海光缆线路维修中,由于现有专用设备性能的局限,对海光缆的打捞一直是一项耗时、耗财、耗力且难度较大的作业。文章介绍了一种以双握切割、两端同持方式剪切打捞海缆的新型设备,它不仅能在2 000 m水深的海底对海光缆进行可靠剪切,还能在剪切后将海缆的两个断头牢固握持,并自行辅接深海打捞所需的钢缆。证明了使用该设备可取代常规打捞的断头打捞,不仅大大提高了维修工作效率,更有效地提高了维修打捞工作的安全性和可靠性。 相似文献
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以水下弹性缆索为研究对象,分析了处理缆索弹性的段前弹簧模型,发展了缆索的多体有限段模型,提出弹性缆段模型,将多体运动力学和弹性力学结合起来,用于求解弹性缆索的动力学响应。对于水下缆索所受的流场力,推导了流场分布力的质心等效力系,并通过揭示水下缆索的附加质量与缆索自身惯性的本质联系,得到了包含附加质量力影响的水下弹性缆索的动力学方程。对工程实例进行了仿真研究,结果与实际情况吻合良好。 相似文献
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Flexible segment model （FSM） is adopted for the dynamics calculation of marine cable being laid. In FSM, the cable is divided into a number of flexible segments, and nonlinear governing equations are listed according to the moment equilibriums of the segments. Linearization iteration scheme is employed to obtain the numerical solution for the governing equations. For the cable being laid, the payout rate is calculated from the velocities of all segments. The numerical results are shown of the dynamic motion and tension of marine cables being laid during velocity change of the mother vessels. 相似文献
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Nonlinear Finite Element Analysis of Ocean Cables 总被引：1，自引：1，他引：1
Nam-ⅡKIM Sang-SooJEON Moon-YoungKIM 《中国海洋工程》2004,18(4):537-550
This study has focused on developing numerical procedures for the dynamic nonlinear analysis of cable structures subjected to wave forces and ground motions in the ocean. A geometrically nonlinear finite element procedure using the isoparamnetrie curved cable element based on the Lagrangian folmulation is briefly summarized. A simple and accurate method to determine the initial equilibrium state of cable systems associated with self-weights, buoyancy and the motion of end points is presented using the load incremental method combined with penalty method. Also the Newmark method is used for dynamic nonlinear analysis of ocean cables. Numerical examples are presented to validate the present numerical method. 相似文献
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Based on the fundamental equation of flexible cable dynamics for a towed system, an easily solved mathematical model is set up in this paper by means of appropriate simplification. Several regular patterns of spatial motion of towed flexible cables in water are obtained through numerical simulation with the finite difference method, and then modification and verification by trial results at sea. A technical support is provided for the towing ship to maneuver properly when a flexible cable is towed. Furthermore, the relations between two towed flexible cables, which are towed simultaneously by a ship, are investigated. The results show that the ship towing two flexible cables is safe under the suggested arrangement of two winches for the towing system, and the coiling/uncoiling sequences of the cables as well as the suggested way of maneuvering. 相似文献
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This paper proposes a geometrically exact formulation for three-dimensional static and dynamic analyses of the umbilical cable in a deep-sea remotely operated vehicle (ROV) system. The presented formulation takes account of the geometric nonlinearities of large displacement, effects of axial load and bending stiffness for modeling of slack cables. The resulting nonlinear second-order governing equations are discretized spatially by the finite element method and solved temporally by the generalized- implicit time integration algorithm, which is adapted to the case of varying coefficient matrices. The ability to consider three-dimensional union action of ocean current and ship heave motion upon the umbilical cable is the key feature of this analysis. The presented formulation is firstly validated, and then three numerical examples for the umbilical cable in a deep-sea ROV system are demonstrated and discussed, including the steady configurations only under the action of depth-dependent ocean current, the dynamic responses in the case of the only ship heave motion, and in the case of the combined action of the ship heave motion and ocean current. 相似文献
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The suction anchor has been widely used in taut or semi-taut mooring systems as an effective and economical solution to anchoring problems. To ensure high reliability, the profile of the mooring cable connecting the fairlead and the pad-eye must be accurately designed. However, previous studies have rarely considered the effect of cable slippage in soil on the mooring behavior, or embedded cables have been studied with an assumed tension at the seabed. This paper, by treating the cable suspended in water and the cable embedded in soil as a single cable, presents a two-dimensional (2D) static model and a three-dimensional (3D) quasi-static model for the cable during pretensioning and in service, respectively. The two models take into account the comprehensive effects of ocean currents, soil resistance and cable elasticity, all of which are critical for the design of a mooring system. Three examples are analyzed using the models and some useful conclusions are drawn. 相似文献
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海坛海峡海底光缆建设是一项加强海坛岛与大陆之间通信的工程。本文介绍了勘察的光缆路由区地形地貌及沉积结构,并分析了相应的水动力情况,在明该段路由区宜于埋设海底光缆,但不同地段的水动力和沉积结构等有异,光缆埋设的深度应有所不同。 相似文献
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埕岛海上石油平台周边海底管道与电缆的探测技术研究 总被引：1，自引：0，他引：1
海上石油平台周边海底管缆密集,管线状废弃物多,且有相互交叉现象,常有管道与电缆分辨不清或将管线状废弃物误判成海底管缆等情况发生。这严重影响了生产运行和作业平台就位的安全,给指挥作业平台插桩、就位、船舶抛锚带来了很多困难和安全隐患。在埕岛油田平台附近海底管道电缆探测技术研究中,利用目前世界上已有的、对海底管缆探测较为有效的各种仪器设备和方法手段,进行了试点研究,从中寻求适合埕岛油田海区海底管道、电缆位置和埋设状况探测的最佳方法和手段。通过试点研究,对探测海底管道和电缆的各种仪器的探测性能、探测方法、探测过程中应注意的事项以及存在的问题进行了较全面的介绍。 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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Subsea production system has been increasingly used in recent South China Sea offshore developments. With deepwater applications, constituent parts of subsea systems become more complicated and enlarged. Increases on the weight and geometry of each component bring challenges to installations. A recent accomplished deployment on a subsea massive jumper shows the weight and length have been up to 120 tons and 90 m, respectively with sophisticated geometry. It is considerably difficult to install heavy and large subsea structures, especially in South China Sea where severe environmental conditions are common. In addition, deepwater deployment may alter natural frequency of the hoisting system and the altered frequency may be close to possible environmental conditions. To deal with the above two issues, traditionally, engineers need to carry out series of complicated numerical analyses which are on case basis and significantly time-consuming. Existing studies focus on the optimization on analysis techniques by conducting laboratory testing and numerical simulations. However, easy-to-use guidance on massive subsea structure installation are somewhat limited. The studies presented in this paper aim to achieve a simplified guidance which can briefly screen the cases subject to axial resonance and provide visible correlations between hoisting system integrity and key installation parameters. 相似文献