Determination of limiting cavity depths for offshore spudcan foundations in a spatially varying seabed. (May 2020)

• Record Type: Journal Article
• Authors: Yi, Jiang Tao; Pan, Yu Tao; Huang, Li Ying; Xu, Shi Jie; Liu, Yong; Phoon, Kok Kwang
• Is Part Of: Marine structures. Volume 71(2020)
• Publication Date: 2020-05
• Subjects: Offshore engineering -- Spudcan foundation -- Limiting cavity depth -- Random finite element analyses -- Spatial variability -- Coupled Eulerian-Lagrangian; Naval architecture -- Periodicals; Offshore structures -- Periodicals; Architecture navale -- Périodiques; Structures offshore -- Périodiques; Naval architecture; Offshore structures; Periodicals; 620.4162
• DOI: 10.1016/j.marstruc.2020.102723
• Languages: English
• ISSNs: 0951-8339

Abstract

Abstract: The importance of accurate prediction of limiting cavity depths during offshore spudcan foundations installation has been variously highlighted in the literature. Nonetheless, most of the previous research is deterministic in nature and confined to homogenous soils. Since offshore clayey soils can be highly spatially variable, there is a practical need to take proper account of the spatial variability in the prediction of limiting cavity depths. In a bid to remedy this situation, large deformation finite element calculations combined with three-dimensional random fields were repeatedly conducted in this study within a Monte-Carlo framework. The continuous penetration of a spudcan initiated from surface was explicitly modeled until a full-localized flow-around mechanism was observed. Spatial variability was found to clearly affect the soil back-flow and thereby the limiting cavity depth, the latter of which takes a range of values that can be approximately modeled as a log-normal distribution. Characteristic limiting cavity depths at various probability levels were ascertained. An algebraic expression was proposed to explicitly predict the characteristic limiting cavity depths in random soils from the fractile. Particular attention was paid to the lower and upper 5% characteristic values, which are likely to be useful for reliability-based design. Highlights: Large deformation random finite element calculations are performed. The spatial variability clearly affects the soil back-flow and thereby the limiting cavity depth. Variation of the limiting cavity depth approximately follows a log-normal distribution. An algebraic expression is developed to predict the characteristic limiting cavity depths.