【作者】 甘进；

【导师】 吴卫国；

【作者基本信息】 武汉理工大学 ， 海洋工程结构， 2012， 博士

【摘要】 海上多功能工作平台结构设计关键技术的研究是非常复杂和具有实际意义的课题,其有益于提高我国海洋工程结构的设计能力和研发水平。本文以琼州海峡跨海大桥工程为背景,针对跨海大桥施工特点,并通过对自升式海洋平台设计理论和方法的研究,完成了海上多功能工作平台的方案设计。采用理论研究、模型试验、数值仿真等多种方法手段,全面深入地研究了平台结构设计直接计算方法、平台极限承载能力分析方法、桩腿结构空间KK管节点疲劳性能以及桩腿结构选型优化设计等海上多功能工作平台结构设计中涉及到的关键技术问题。本文研究的主要内容包括：(1)根据国内外已有自升式海洋平台的结构型式和特点,在广泛阅读国内外文献,深入分析已有研究成果的基础上,对平台结构设计所涉及的关键技术进行了消化、吸收和总结。根据琼州海峡跨海大桥工程的基本建设条件和施工特点,提出了海上多功能工作平台的总体设计方案。设计的海上多功能工作平台具备在复杂恶劣的海洋环境中安全高效地完成跨海大桥建设中的深水打桩及基槽整平等施工作业的能力,作业最大水深达到80米。模块化技术的引入使海上多功能工作平台的总体方案更加符合大型海洋工程装备发展趋势,使平台真正具备了“多功能性、多用途性、良好经济性”的特点。(2)深入分析海上多功能平台的结构型式和海上作业特点,并研究了海上多功能工作平台结构设计直接计算方法,在此基础上,采用有限元分析软件ANSYS,结合相关海洋平台设计建造规范建立了海上多功能工作平台结构强度分析模型。根据对平台风、浪、流等环境载荷的计算方法和准则的研究,提出了海上多功能工作平台最不利环境载荷的计算分析方法。对海上多功能工作平台自存、升降、正常工作及拖航等四种工况下的结构强度进行了分析。根据计算分析结果可以全面了解平台结构各工况下的受力特性,所采用的结构设计直接计算方法可用于平台的结构设计、强度评估以及结构优化等方面。(3)以非线性有限元为基础,采用了静力弹塑性分析方法对海上多功能工作平台极限承载能力进行了研究,重点分析了自存工况下平台受到0°、45°、90°三种不同方向环境载荷作用下平台的极限承载能力,以及平台后服役期考虑碰撞损伤、构件缺失、腐蚀、海生物附着和桩基沉降五种损伤的缺陷平台的极限承载能力,得到了对海上多功能工作平台结构极限承载能力最不利的工况,并通过平台强度储备系数评价了各种损伤对平台极限承载能力的影响程度,提出了有价值的建议。(4)采用模型试验与数值仿真两种方法对海上多功能工作平台桁架式桩腿结构的典型节点型式——空间KK型管节点的疲劳性能进行了相关研究。试验研究主要是通过开展空间KK型管节点在轴力作用下的疲劳性能试验,重点研究KK型管节点在轴力作用下沿着焊缝周围的热应力区内的热点应力分布、节点的应力集中系数,以及初始疲劳裂纹出现位置和裂纹扩展规律等。基于ANSYS平台建立了空间KK型管节点疲劳性能仿真分析模型,分析研究了空间KK型管节点的几何参数对其疲劳性能的影响,提出了提高空间KK型管节点疲劳性能的设计意见。(5)研究了基于有限元法的海洋平台桁架式桩腿结构选型优化设计的方法。应用ANSYS程序的参数化设计语言建立了以降低结构质量减小制造成本为优化目标,以桩腿构件的截面尺寸和桩腿结构的形状参数为设计变量,遵照设计规范中的强度、刚度和稳定性等多约束条件的平台桁架式桩腿结构优化设计模型,并编译了结构优化分析程序。以海上多功能平台设计方案为基础对海洋平台桩腿结构进行了选型优化设计。优化结果表明通过结构优化得到的桩腿设计方案可有效减少结构质量提高平台的经济性,并且采用合理的桩腿结构,不仅可以有效降低用钢量,而且能有效的控制平台的应力和位移响应。(6)对海上多功能工作平台的结构强度分析、极限承载能力分析、空间KK型管节点数值仿真分析和桩腿结构选型优化均是以有限元分析软件ANSYS作为计算分析平台,并根据具体的研究内容和研究方法调用合适的程序模块或编译合理的分析程序完成本文相关研究工作。提出了一套基于ANSYS计算平台研究和解决海上多功能工作平台结构设计中的关键技术问题的方法和思路。更多还原

【Abstract】 The topic of the research on key technologies for multi-purpose jack-up platform structure design is very complex and has practice significance, and it is beneficial to improve the design ability and research level of Chinese ocean engineering structure. In this thesis, taken the Chinese Qiongzhou strait bridge construction project as the research background, and considered the characteristics of bridge construction, the multi-purpose jack-up platform scheme design was completed according to the design theories and methods of offshore jack-up platform. Kinds of methods included theoretical research, model test and numerical simulation were used to research the key technologies of multi-purpose jack-up platform structure design such as the calculation method for the platform structure design, the ultimate load bearing capacity analysis method, the fatigue properties of tubular KK-joints of leg structure and the optimum lectotype design of leg structure. The main research contents of the thesis include:(1) According to the structural types and characteristics of existing jack-up platforms,based on the comprehensive reading of references and the thorough analysis of existing research results, the methods and related research on key technologies of jack-up platform structure design were digested, absorbed and summarized. On the basis of the construction condition and characteristics of Qiongzhou strait bridge construction project, the general design plan of multi-purpose jack-up platform was proposed. The multi-purpose jack-up platform should be able to complete a lot of bridge construction tasks, such as deep water pilling and foundationtrench leveling, in complex and harsh ocean environment safely and efficiently. The maximum operating water depth of the platform reaches80meters. The application of the modular technology made the general design plan of multi-purpose jack-up platform accord with the development trend of large marine engineering equipments, and the multi-purpose jack-up platform really have the characteristics of multi-purpose, versatility and good economy.(2) The structural types and offshore operation characteristics of multi-purpose jack-up platform were deeply analyzed and the structure design calculation methods of the platform were studied. On this basis, the multi-purpose jack-up platform structure strength analysis model were established by the finite element analysis software ANSYS as well as related marine platform design rules and construction rules. According to the research on calculation methods and principles of wind, wave and current to the platform, the worst environmental load calculation analysis method of the platform were put forward. The structure strength was analyzed under the conditions of survival, lift, normal operation and towage. According to the results, the mechanical characteristics of the platform under different conditions can be fully understood, the structure design calculation method offered by the thesis can be applied to the structure design, strength evaluation and structure optimization of the platform.(3) Based on the nonlinear finite element method, the ultimate load bearing capacity of multi-purpose jack-up platform were studied by static pushover analysis method. The ultimate bearing capacities of the platform were analyzed in both intact situation and damaged situations under the direction of0°,45°and90°environment load. The damaged situations contain collision injury, missing component, corrosion, marine growth attachment and pile foundation settlement. The worst cases of the ultimate load bearing capacity of the platform in different situations were obtained. The Reserve Strength Ratios (RSR) of the platform in different situations were calculated to evaluate the effects of the ultimate bearing capacities of the platform, and some valuable proposals were given.(4)Using the model test and numerical simulation methods, the fatigue properties of multi-planar tubular KK-joints which are the typical joint type in the truss legs of the multi-purpose jack-up platform was carried. The main tasks of experiment study are:testing the fatigue properties of KK-joints model under axial loading, obtaining the hot spot stress (HSS) distribution and the stress concentration factors(SCF) along the weld toe in the HSS region, finding the initial fatigue crack position and crack propagation law, etc.. Based on ANSYS software, the simulation models of the multi-planar tubular KK-joints were established to analyze the fatigue properties, and some geometric parameters which influence the fatigue properties of KK-joints were investigated. The proposals improved the fatigue properties of KK-joints were given.(5) Based on the finite element method, the methods of the lectotype optimization design of platform leg structure were studied. The platform leg optimization design model were established with ANSYS parametric design language in order to reduce weight and manufacturing cost, with the section sizes and shapes of the legs as the design variables, the strength, stiffness and stability of the design specifications as constraint conditions, and the optimized structural analysis program were compiled. The optimization results showed that optimized design scheme of legs can effectively reduce the structure weight and improve the economical efficiency of the platform, and, the use of reasonable leg structure can not only reduce the total steel quantity but also control stresses and displacement responses of the platform effectively.(6) In this thesis, the finite element analysis software ANSYS were chosen as the main calculation and analysis platform for the structure strength analysis, ultimate load bearing capacity analysis, tubular KK-joints numerical simulation analysis and leg structure optimum lectotype design of multi-purpose jack-up platform. According to the specific research contents and methods, the appropriate program modules were chosen and the reasonable analysis programs were compiled for the completion of related research work. The methods and ideas, which to study and solve the key technologies of multi-purpose jack-up platform structure design based on ANSYS platform were proposed.更多还原