【作者】 修宗祥；

【导师】 杨秀娟； 冯永训；

【作者基本信息】 中国石油大学 ， 工程力学， 2010， 博士

【摘要】 深水导管架海洋平台由于工作水深较大,施工方便等优点,得到快速发展和推广。但由于深水导管架海洋平台自身复杂的结构、庞大的体积、昂贵的造价以及极恶劣的工作环境,对其安全性与经济性提出了更高的要求。本文依托中石化应用基础项目-“深水导管架平台关键技术研究”,通过理论推导、数值模拟、工程实例分析及配套软件开发等手段,重点开展了深水导管架海洋平台安全可靠性分析及优化设计的研究。本文主要研究内容如下:(1)基于非线性地基梁理论,采用非线性土弹簧模型模拟桩-土相互作用,建立了深水导管架海洋平台非线性动力分析模型。对比分析了采用等效桩法与考虑桩-土耦合法时平台的振动模态及关键部位处位移、速度及加速度的动力响应规律;考虑了桩-土耦合法计算时的群桩效应问题,分析了海底表层土性质、桩间距及桩径对平台动力响应的影响规律。(2)采用时程分析法对平台在地震载荷作用下的非线性动力响应进行分析,并与反应谱法计算结果进行了对比研究。分别运用IDA方法及Pushover法对深水导管架平台的抗震性能进行分析,并对Pushover法不同侧力加载模式的适用性与准确性进行分析比较,得到了适合深水导管架海洋平台的侧力加载模式。针对平台设计参数、材料参数、地震载荷的随机性,建立了平台在地震作用下的动力可靠性分析模型,并进一步考虑了地震导致的土层液化对平台动力可靠性的影响。(3)针对深水导管架海洋平台在随机波浪载荷作用下的疲劳问题,采用能够准确考虑海洋波浪能量沿整个频率范围分布情况的谱分析方法,并引入结构可靠性理论,建立了深水导管架海洋平台的疲劳可靠性模型,并同基于等效Weibull分布方法的计算结果进行了对比。(4)由于深水导管架平台疲劳问题突出,因此,要设计合理的平台结构形式,必须考虑平台的疲劳性能。本文通过MATLAB编程实现了Hooke-Jeeves直接优化算法,将ANSYS有限元软件作为求解器进行深水导管架海洋平台的动力响应及疲劳可靠性计算,并将疲劳可靠性指标作为优化的一项约束条件,通过MATLAB循环调用批处理模式下的ANSYS软件实现最终的平台结构优化分析过程。同时,引入一种可行的简化方法,即先进行极限静力载荷工况下的导管架海洋平台静力优化分析,然后在静力优化的基础上,将平台固有频率和安全疲劳可靠性指标作为约束条件进行动力优化分析。(5)针对深水导管架海洋平台选型这一复杂问题,基于层次分析法、综合模糊评判方法等理论,引入三级模糊优选决策理论以及专家群组评判可信度方法建立了深水导管架海洋平台模糊优化选型模型。以200m水深导管架海洋平台为例,对平台四种方案进行综合模糊优选。(6)以风险评估理论和模糊数学理论为基础,结合深水导管架海洋平台设计施工特点,对平台上驳过程、拖航过程和下水过程中不确定因素潜在的风险进行了分析。通过故障树法对各个过程的风险因素进行识别,并建立对应的故障树模型。引入基于专家群组可信度方法求解各风险因素的相对权重、各因素的发生概率隶属度以及各因素的后果严重程度隶属度。最后编制了针对深水导管架上驳过程、拖航过程及下水过程的综合施工风险评估程序。更多还原

【Abstract】 The deep water jacket platform has been fast developed and generalized,because of the advantages of greater operating water depth and convenient construction. However, in consideration of the complicated structure, huge size, expensive cost and the adverse working conditions, the safety and economics of deep water jacket platform has been put forward higher demand. In this study, the safety reliability analysis and optimization design of deep water jacket platform were emphatically researched by means of theoretical derivation, numerical simulation, engineering example analysis and corresponding software development, on the basis of applied basic research project of China Petroleum & Chemical Corporation-“The key technology research of deep water jacket platform”The main research contents of this thesis are as follows:(1)Based on the nonlinear foundation beam theory, the nonlinear dynamic analysis model of deep water jacket platform was established, with the nonlinear soil spring model used to simulate the interaction of pile and soil. The vibration mode and the dynamic response rules of displacement, velocity and acceleration of key position, which were computed respectively by equivalent pile method and pile-soil interaction method, were comparatively analyzed; The group effect was considered when the pile-soil interaction method was used, and the influence laws of seabed surface layer property, pile spacing and pile diameter to dynamic response of platform were analyzed.(2)The nonlinear dynamic response of the deep water jacket platform under the earthquake load, was computed by the time history analysis method and the results were compared with response spectrum method. The seismic behavior of the deep water jacket platform was analyzed by IDA method and Pushover method respectively;The accuracy and applicability of different lateral load patterns for Pushover analysis method was studied, and the most suitable lateral load patterns for deep water jacket platform was obtained. Aiming at the randomness of design parameters, material parameters and seismic load, the dynamic probability analysis module for deep water jacket platform was established, and then the influence of soil liquefaction caused by earthquake on dynamic probability of platform was analyzed.(3)Considering the fatigue problems of deep water jacket platform under random wave forces, the spectrum analysis method was introduce, which can describe the distribution of wave energy exactly along the whole frequency domain. Then, the fatigue reliability model was established by the structural reliability theory and the calculation results were compared with those by equivalent Weibull method.(4)Because the fatigue problem was a serious problem for deep water jacket platform, to get a reasonable platform structure design, it is necessary to consider the fatigue property of the platform.The Hooke-Jeeves direct search optimization algorithm was realized by using the MATLAB software; the ANSYS program was used as an equation solver to calculate the dynamic response and fatigue reliability of deep water jacket platform; the ANSYS program was circularly called in patch model by MATLAB, so the optimization analysis process was performed with the fatigue reliability index as an optimization constraint.At the same time, a feasible simplified optimization method was introduced, in which a static optimizing analysis of platform under static extreme load was performed firstly, and then the dynamic optimum analysis was performed on the basis of the static optimization analysis results with natural frequency and fatigue reliability index as constraint conditions.(5)The optimization lectotype of deep water jacket platform is a complicated system question. According to analytic hierarchy process method and comprehensive fuzzy evaluation method, the fuzzy optimization model for optimum lectotype of deep water jacket platform was established, basing on three-level fuzzy evaluation method and expert group credit degree methods. Finally, a jacket platform for 200 m water was taken as an example; a fuzzy optimum selection was performed between the four initial schemes.(6)Basing on risk assessment theory and fuzzy mathematics theory, the potential risks caused by uncertain factors during the process of loading-out, towing and launching for deep water jacket platform were analyzed, in consideration of the design- construction properties of deep water jacket platform .The risk factors for each process were identified by fault tree method, and the corresponding fault tree model was established. The relative weights, the memberships of occurrence probability and accident consequences of risk factors were obtained by expert group credit degree methods. Finally, the risk assessment software was developed for the process of loading-out, towing, and launching.更多还原