一种适用于深水浮式结构的新型系泊系统及其耦合运动分析方法研究

Traditional catenary mooring system has demonstrated many drawbacks as water depth increases. As a result, it will not only increase production costs, decreases the vessel useful payload, but also increases the movement of the floating structures. Althogh a taut mooring system has many merits such as bringing decreases in mooring radius and easy to install,it has a higher requirement for the uplift resistance,and a evident increase in the cost of anchor. By considering the merits and demerits of catenary mooring system and taut mooring system, a new mooring system integrating catenary with taut mooring is proposed in this project, which can be applied to deepwater floating structures. The new mooring system can ensure a better working condition, fall the risk of collision between mooring lines and other undersea equipment and reduce the anchors costs.Meanwhile,fluid force, non-uniform distribution of the mass of the mooring line,and the movement amplitudes of the platform are taken into during analyzing the dynamics of the mooring line. Finite element method and three-dimensional elastic rod theory are adopted to build the dynamic equation of mooring line. Furthermore six-degree coupled dynamic euqations of floating structure and mooring system are built by deducing the nonlinear and dynamic stiffness matrix and considering the effect of fluid-structure interaction. Furthermore,a new dynamic couped analysis method which can solve the coupled dynamic response of deepwater floating structure with a complicated type of mooring system, will be developed by using the numerical method in time domain. In order to expound and validate the developed coupled analysis mehtod and the advantages of this new system,some model experiments of a typical deepwater floating structure with the new mooring system are conducted.

随着水深的增加，悬链线系泊系统成本增加过大，同时会造成平台有效承载力降低、偏移量过大；张紧式系泊系统虽然具有系泊半经小、可应用于较深海域的优点，但对锚的垂向抗拔性能要求很高，增加了锚的成本。鉴于以上两种系泊系统的优缺点，本项目提出一种适用于深水的新型悬链与张紧结合式系泊系统的设计方法，该系泊系统充分结合二者优点，能够改善深水海洋平台工作条件、降低缆索破断风险、降低锚的成本。在此基础上，计及流体力、系泊质量非均布以及平台运动幅度对系泊动力特性的影响，综合采用有限元方法、三维弹性杆理论建立系泊系统的运动方程，并通过推导系泊链端非线性动态刚度矩阵计算表达式，考虑流固耦合作用，建立平台-新型系泊系统的六自由度耦合运动方程，进而基于时域分析理论建立一种新的可解决平台-复合型系泊系统的耦合运动分析方法，并以典型深水海洋平台为例，通过模型试验验证所发展耦合分析方法的正确性和新型系泊系统的优越性。

本项目充分结合悬链线系泊系统与张紧式系泊系统的优点，提出了一种适用于深水的复合型系泊系统设计方法。针对新型复合型系泊系统，计及流体力、系泊质量非均布以及平台运动幅度对系泊动力特性的影响，综合采用有限元方法、三维弹性杆理论建立系泊系统的运动方程，考虑流固耦合作用，建立平台-新型系泊系统的六自由度耦合运动方程，基于时域分析理论建立一种新的可解决平台-复合型系泊系统的耦合运动分析方法。为了进一步开展深水模型试验研究，建立了深水浮式海洋平台大截断因子耦合运动响应混合模型试验方法，以典型深水海洋平台为例，在中国船舶科学研究中心波浪水池中开展了新型系泊系统的模型试验研究，试验结果验证了所建立的深水浮式平台-复合型系泊系统耦合运动分析方法和混合模型试验方法的正确性以及新型复合型系泊系统的优越性能，如，适用水深范围可达500m-3000m，能够改善浮体的运动性能、有效降低系泊缆索的张力峰值、有效降低对锚的抗拔性能的要求。通过上述研究工作的开展，本项目取得了较多的研究成果，发表学术论文9篇，其中SCIE检索7篇；参加国际学术交流2次，国内学术交流3次；培养研究生4名；获得江苏省科学技术奖一等奖1项、教育部科技进步一等奖1项。