Undrained bearing capacity of deeply embedded skirted spudcan foundations under combined loading in soft clay

• Published in: Marine structures 2019-07, Vol.66, p.164-177
• Main Authors: Yin, Shuai, Yi, Jiang Tao
• Format: Article
• Language: English
• Subjects: Aspect ratio; Bearing capacity; Clay; Combined loading; Deep water; Drilling; Drilling rigs; Envelopes; Finite element method; Horizontal loads; Jackup platforms; Numerical analysis; Offshore; Offshore drilling rigs; Ratios; Series (mathematics); Skirted foundations; Soft clay; Spud-can foundations; Vertical loads
• ISSN: 0951-8339; 1873-4170
• DOI: 10.1016/j.marstruc.2019.04.005

The mobile jack-up drilling rigs supported by individual foundations are gradually extended to deep water for drilling activities in the offshore industry. These individual foundations are expected to provide considerable bearing capacity and moment fixity to ensure the entire system safety under the combined vertical, horizontal and moment loadings. Spudcan fitted with skirt at deep embedment may provide additional capacity to meet these demands. This paper carries out a series of probe tests using finite element analysis to investigate the potential benefits of deeply embedded skirted spudcan foundations under combined loading in soft clay. Four discrete skirt aspect ratios are considered to discuss the effects of the skirt length on the various bearing capacities. The failure envelopes for each of them are presented to identify the potential benefits. The results show that both the size and the shape of the failure envelopes changed greatly with increasing skirt aspect ratio. A modified analytical expression related to the skirt aspect ratio is proposed to interpret and predict the behavior of deeply embedded skirted spudcan foundations. •The potential benefits of deeply embedded skirted spudcan foundations under combined loading in soft clay were investigated.•The effects of the skirt length on the various bearing capacities were discussed.•The size and the shape of the failure envelopes changed greatly with increasing skirt aspect ratio.•A modified analytical expression related to the skirt aspect ratio is proposed.