基于腐蚀疲劳裂纹扩展的自升式海洋平台桩腿时变可靠性研究

Research on Time-dependent Reliability of Jack-up Platform Pile Leg Based on Corrosion Fatigue Crack Propagation

文章研究了腐蚀与疲劳载荷耦合作用下自升式平台桩腿服役可靠性问题。采用ANSYS对自升式海洋平台桩腿结构进行建模,根据平台服役海域的波浪散布图对桩腿结构的工况进行划分,确定浪溅区桩腿结构的疲劳关键节点及其等效应力。以桩腿材料E690高强度钢为对象,进行腐蚀疲劳裂纹扩展试验,获得了不同环境下的疲劳裂纹扩展参数。提出了基于断裂力学的浪溅区桩腿关键节点的时变可靠性模型,与采用现有腐蚀模型的桩腿时变可靠性指标进行了对比,结果表明,文章所提出的方法能有效地反映平台桩腿服役期间关键节点的时变可靠性变化趋势,为平台在服役期间的安全运行与维护保养提供了理论指导。

The reliability assessment of the jack up platform pile leg under the condition of corrosion environment and fatigue load is researched. The model of self elevating offshore platform pile leg structure was established by ANSYS. The stress response analysis under different wave force spectrum was analyzed to determine the fatigue critical nodes in the splash zone structure, and the equivalent stress of the key nodes. The corrosion fatigue crack propagation experiment was carried taking E690 high strength steel as the object and the fatigue crack propagation parameters under different environment were obtained. Based on the time-dependent reliability model, the reliability of the key nodes was calculated respectively according to the experimental parameters and corrosion model parameters, the calculation results of two methods were compared. The results show that the reliability model based on corrosion fatigue crack propagation experiment can reflect the changing trend of the key nodes in the corrosion zone. Then combined with the service time, the time variant reliability trend was analyzed, references for safe operation and maintenance of jack-up platform during service were provided.