动态海底电缆极限工况生存与耐久性设计
Survival and Durability Design of Dynamic Submarine Cable Under Extreme Operating Conditions
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摘要: 极限海况导致漂浮式平台发生剧烈运动和大范围偏移,对平台系泊系统和动态管缆造成直接冲击。动态海底电缆由平台悬挂敷设至海床,为适应平台运动,在海水中通常呈现“缓波”构型。极限海况下生存能力和长期动态载荷作用下的耐久性,是动态海底电缆核心设计目标。本文基于福建南日岛海域长期海洋环境统计参数,采用威布尔分布拟合方法,获取5年到100年不同重现期下的极限波浪与洋流工况参数。依据相关设计标准,通过水动力分析和有限元计算,对国内某已投运的漂浮式风力发电机动态海底电缆开展宏观载荷分析和局部应力计算,完成极限承载能力校核。同时,统计该海域波浪年度方向分布和作用时长,采用时域分析方法及线性累计损伤理论,对动态海底电缆疲劳寿命进行校核。基于上述分析结果,建立了动态海底电缆全尺寸疲劳寿命设计和测试方法体系。研究成果完善了国内动态海底电缆设计流程,可为深远海能源和资源开发漂浮式平台配套动态海底电缆极限工况生存和耐久性设计提供技术参考和工程借鉴。Abstract: Extreme ocean waves and currents are the main causes of the violent movement and large-scale excursion of floating platforms, and they also directly impact dynamic submarine cables and mooring system. Dynamic cables are suspended from the platform to the seabed and present 'Lazy wave' configuration in the water-column to accommodate the platform’s motion. Their survivability under extreme sea conditions and durability under long-term marine environmental loads are the primary design objectives. Based on the typical marine environmental conditions of the floating wind turbine operation location in Nan Ri Island, Fujian Province, the Weibull statistical method was employed to model extreme wave and current conditions for 50-year and 100-year return periods. In accordance with design standards, hydrodynamic analysis and finite element software were utilized to conduct global loads analysis and local stress calculations for the submarine cable of a floating wind turbine successfully commissioned in China, thereby verifying its ultimate load-bearing capacity. The annual distribution and duration of wave parameters were statistically analyzed, and time-domain calculation methods combined with linear cumulative theory were used to verify the fatigue life of the submarine cable. Based on the fatigue life analysis results, a full-scale fatigue life test matrix for dynamic submarine cables was established, providing a reference and guidance for the survival and durability design of submarine cable under extreme conditions.
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