Abstract Spudcan foundations for mobile jack-up units are large diameter conical foundations that can penetrate into the seabed to a maximum depth of three times the diameter of the spudcan. As a deeply penetrated foundation, the bearing capacity of a spudcan is highly dependent on the failure mechanism and the strength distribution of the seabed soil, which exhibits strong spatial variability. While many recent studies have explored the failure mechanism and bearing capacity of spudcan foundations, these studies have commonly deterministically described the soil in which the spudcan is embedded. Therefore, this paper aimed to investigate the probabilistic bearing capacity of spudcan foundations embedded in the seabed at various depths, under the condition of spatially variable undrained shear strength that increased linearly with depth. The random finite element method was used to study this problem, where nonlinear finite element analysis was combined with random field theory within a Monte Carlo framework. The variability in undrained shear strength was modelled as a random field and characterised by a log-normal distribution with anisotropic autocorrelation distances. The influence of autocorrelation distance on the mean bearing capacity and the failure mechanism was discussed for each embedment depth. A correlation between the probability of failure and the factor of safety was established based on the obtained results. These findings can provide guidance for reliability-based design of spudcan foundations embedded in spatially variable soil.

中文翻译：

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基于非平稳随机有限元法的不同深度埋入桩基承载力及可靠度分析

摘要 移动式自升式平台桩基是大直径圆锥形基础，可深入海床，最大深度为桩基直径的三倍。作为深穿透地基，桩靴的承载力高度依赖于破坏机制和海底土壤的强度分布，具有很强的空间变异性。虽然最近的许多研究探索了桩靴基础的破坏机制和承载能力，但这些研究通常确定性地描述了桩靴嵌入的土壤。因此，本文旨在研究在随深度线性增加的空间可变不排水抗剪强度条件下，埋入不同深度海床的桩桩基础的概率承载力。随机有限元方法被用来研究这个问题，其中非线性有限元分析与蒙特卡罗框架内的随机场理论相结合。不排水剪切强度的可变性被建模为随机场，并以具有各向异性自相关距离的对数正态分布为特征。讨论了自相关距离对平均承载力的影响以及每个埋置深度的破坏机制。根据获得的结果建立故障概率与安全系数之间的相关性。这些发现可以为嵌入在空间可变土壤中的 spudcan 基础的基于可靠性的设计提供指导。其中非线性有限元分析与蒙特卡罗框架内的随机场理论相结合。不排水剪切强度的可变性被建模为随机场，并以具有各向异性自相关距离的对数正态分布为特征。讨论了自相关距离对平均承载力的影响以及每个埋置深度的破坏机制。根据获得的结果建立故障概率与安全系数之间的相关性。这些发现可以为嵌入在空间可变土壤中的 spudcan 基础的基于可靠性的设计提供指导。其中非线性有限元分析与蒙特卡罗框架内的随机场理论相结合。不排水剪切强度的可变性被建模为随机场，并以具有各向异性自相关距离的对数正态分布为特征。讨论了自相关距离对平均承载力的影响以及每个埋置深度的破坏机制。根据获得的结果建立故障概率与安全系数之间的相关性。这些发现可以为嵌入在空间可变土壤中的 spudcan 基础的基于可靠性的设计提供指导。讨论了自相关距离对平均承载力的影响以及每个埋置深度的破坏机制。根据获得的结果建立故障概率与安全系数之间的相关性。这些发现可以为嵌入在空间可变土壤中的 spudcan 基础的基于可靠性的设计提供指导。讨论了自相关距离对平均承载力的影响以及每个埋置深度的破坏机制。根据获得的结果建立故障概率与安全系数之间的相关性。这些发现可以为嵌入在空间可变土壤中的 spudcan 基础的基于可靠性的设计提供指导。