自升式海洋平台桩腿的结构强度分析及优化设计

发布时间：2019-03-01 19:22

【摘要】：自升式钻井平台是移动式海洋平台,在海洋石油开发中最为常用。海洋平台是海洋油气资源开发的基础性的设施,所处海洋环境恶劣,风、海浪、海流、地震等灾害威胁着平台结构的安全,结构疲劳强度和极限强度受到严重影响。桩腿作为海洋平台的支撑结构,影响着平台的安全以及稳定性,而桩腿所用材料昂贵,对桩腿优化要考虑桩腿的动力性能,所以对桩腿采取的是基于动力性能的多目标优化。首先,对自升式海洋平台静力动力分析。利用软件建立自升式海洋平台三维模型,根据环境载荷的入射角讨论5种工况,根据规范施加边界条件,载荷根据甲板载荷图施加,完成静力分析以后,选取最危险的一种工况,进行动力分析,并校核桩腿的屈服以及屈曲强度。其次,对桩腿结构进行单目标优化。对桩腿进行分段,以桩腿厚度为设计变量,动位移、动应力以及固有频率为约束条件,优化时,质量为目标函数,若只考虑质量最小,桩腿厚度的取值偏向与设计变量的下限。然而,表现平台振动情况的加速度变大了,所以有必要进行多目标优化。最后,对桩腿进行多目标优化。首先对设计变量分析其对桩腿加速度的灵敏度,采取与单目标优化相同的设计变量以及约束条件。目标函数是质量最小以及自存工况下加速度最小。
[Abstract]:Jack-up drilling platform is a mobile offshore platform, which is most commonly used in offshore oil development. The offshore platform is the basic facility for the exploitation of offshore oil and gas resources. The marine environment is harsh, such as wind, waves, currents, earthquakes and other disasters threaten the safety of the platform structure, structural fatigue strength and ultimate strength are seriously affected. As the supporting structure of the offshore platform, the pile leg affects the safety and stability of the platform, and the material used for the pile leg is expensive. Therefore, the dynamic performance of the pile leg should be considered in the optimization of the pile leg, so the multi-objective optimization based on the dynamic performance is adopted for the pile leg. First of all, the static and dynamic analysis of the self-elevating offshore platform is carried out. A three-dimensional model of a self-elevating offshore platform is established by using software. Five working conditions are discussed according to the incident angle of the environmental load, the boundary conditions are applied according to the code, the load is applied according to the deck load diagram, and the static analysis is completed. The most dangerous condition is selected for dynamic analysis, and the yield and buckling strength of pile leg are checked. Secondly, the single-objective optimization of the pile-leg structure is carried out. Taking pile leg thickness as design variable, dynamic displacement, dynamic stress and natural frequency as constraint conditions, the quality is taken as objective function in optimization. If the minimum mass is considered, the value deviation of pile leg thickness and the lower limit of design variable are considered. However, the acceleration of the vibration of the platform increases, so it is necessary to carry out multi-objective optimization. Finally, the multi-objective optimization of the pile leg is carried out. Firstly, the sensitivity of the design variable to the acceleration of the pile leg is analyzed, and the same design variables and constraint conditions as the single objective optimization are adopted. The objective function is the minimum mass and the minimum acceleration under self-stored condition.
【学位授予单位】：浙江海洋大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U661.43

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