自升式平台桩腿结构在实际海洋环境中会受到海底土体的侧向支撑作用，导致屈曲性能显著变化。为研究土体作用对桩腿屈曲特性的影响，设计了计及土体作用的两端简支圆管屈曲试验，考虑不同插深深度和土体密实度，开展试件屈曲模式和有效长度系数研究，定量分析了插深和土体抗力对试件屈曲特性的影响。结果显示高密实度和大插深比条件下试件的有效长度系数较无土工况降低34%。基于Winkler地基梁理论和试验结果，提出了一种基于密实度的土弹簧刚度分段模型分析试件屈曲特性，采用该模型的数值仿真结果与试验结果吻合良好。研究成果可为桩腿设计优化和成本控制提供一定的参考。

英文摘要:

In marine environments, jack-up platform legs are subjected to lateral support from seabed soils, which significantly alters their buckling behavior. To investigate the influence of soil resistance on the buckling characteristics of the legs, buckling tests were performed on simply supported tubular specimens considering varying embedment depths and soil compaction levels. The study analyzed the buckling modes and effective length factors, and quantitatively assessed how embedment and soil stiffness influence structural stability. Results indicate that, under high compaction and large embedment ratio conditions, the effective length factor decreased by up to 34% compared to conditions without soil support. Based on Winkler foundation theory and experimental observations, a segmented soil spring stiffness model incorporating soil compaction was developed. Numerical simulations based on this model exhibited strong agreement with experimental outcomes. The findings offer theoretical support and practical references for optimizing leg design and improving cost efficiency.

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