【作者】 谢波涛；

【导师】 李华军； 刘德辅；

【作者基本信息】 中国海洋大学 ， 港口、海岸及近海工程， 2010， 博士

【摘要】 海洋平台结构是海洋油气资源开发的基础性设施,是海上生产作业和生活的基地。每年夏季台风、飓风诱发的狂风、巨浪等极端环境荷载都会给海洋平台结构带来考验；一旦发生事故,不仅会给国家带来巨大的经济损失和社会影响,其造成的海洋污染将是灾难性的。2005年Katrina飓风导致美国墨西哥湾平台倒塌的事故使我们认识到：对极端环境荷载考量不足使得平台标高、设防标准偏低；以及平台老化导致的抗力衰减使其不能承受极端载荷的作用是此次事故中平台大量倒塌的重要原因。为达到减小环境荷载设计风险,了解和掌握服役期平台可靠度的目的,本文做了以下三点创新性工作：●本文结合复合极值分布理论,提出了海洋环境荷载参数设计风险概念和海洋平台标高求解法。对因极值模型、取样方法、取样区间、参数求解方法等方面存在的各种不确定性而导致的设计风险进行了探讨；并使用了多维复合极值分布模式,对天文大潮、风暴潮、波高各因素同时出现的极端海况进行了概率预测,并用于平台标高的确定。●海洋平台的构件缺陷、机械损伤、疲劳和裂纹扩展的损伤积累等不利因素都将导致平台整体抗力的衰减、影响结构的服役安全度和耐久性。因此基于时变可靠度理论的海洋平台风险分析具有更重要的理论和实际意义。鉴于以往研究只侧重结构抗力时变衰减研究,忽视对环境荷载时变性问题的考虑,本论文在研究了腐蚀、海生物等对平台抗力衰减的时变分析后,提出基于贝叶斯理论和等效荷载法的海洋环境荷载时变可靠度求解法。由于本方法使用服役期内结构真实环境资料对环境荷载参数进行了更新,因此可靠度计算结果更加合理。●台风灾害由南到北,遍及我国沿海各省；而我国目前已探明油气资源在渤海、黄海、东海、南海等海域均有分布。由于地理位置、海洋环境等方面的不同,不同海区台风的气象特征及致灾因素往往也呈现较大差异。为使海洋环境条件研究成果更好地为海洋产业规划和资源开发服务,构建海洋环境条件的参数区划是发展的必然趋势。本论文在自主研发的“台风灾害区划、设防标准双层嵌套模式”基础上,对我国海区进行了区划研究：即考虑了各海区台风强度、频次及其诱发的各种灾害的机制及概率特征,以此为基础构建了我国各海区台风灾害区划,研究成果可为我国海洋工程的防灾规划及设防标准制定提供重要参考。更多还原

【Abstract】 Offshore platforms are the basic facilities for offshore oil exploitation and worker living. The extreme environment loading induced by typhoons and hurricanes in ever summer gives austere challenge to offshore platform structure. The platform will result huge economic loss and social impact in the event of platforms failure. Hurricane Katrina and Rita in 2005 resulted in the largest number of destroyed and damaged platforms in the history of Gulf of Mexico operations. The lessons from accident have taught us that the lower defence criteria of the platform and structure resistance reduction are the chief reason for the failure.In order to reduce the risk in the design stage and realize and command the reliability of existing platforms, this thesis performed three innovative studies as followed.●Based on the compound extreme value distribution, the concept of parameters design risk for ocean environmental load and Solving Method of platform deck elevation against the largest hurricane are proposed in this thesis.The risks in the design stage caused by uncertainties existing in extreme theory, sampling method, samples interval and statistics parameters solving method are discussed and the multivariate compound extreme value distribution (MCEVD) model is used to predict the deck elevation with different combination of tide, surge height and crest height.●Under the action of natural and service environments, the performance of structure in the course of long-term service will deteriorate gradually due to components defect, mechanical damage, fatigue and material deterioration, which would cause structural resistance and reliability to decrease.The research of time-dependent reliability has important theoretic and practical meaning. Previous studies pay more attention to the structure resistance deterioration while ignoring the dynamic characteristics of ocean environment loads.The deterioration of ultimate bearing capacity caused by corrosion and marine growth was research and the time-dependent reliability of environment loads solving calculation method which based on the Bayesian theory and equivalent load method was proposed in this thesis.The calculations predicted by this method were reasonable because of the environment loads updating.●All of the ocean oilfields are in the typhoon-affected region in China and the typhoon characteristics and disaster factors are different. For prevention and mitigation of typhoon disasters in offshore engineering, in this paper a double-layer nested model of typhoon disaster zoning and prevention criteria is proposed. Considering the frequency and intensity of typhoon and its induced disaster, the sea area zoning was proposed and it will supply reasonable references to decision-making of protection criterion and risk assessment for offshore engineering.更多还原