Back-calculated operative sand friction angles from 384 spudcan penetration records in sandy seabeds

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4. Back-calculated operative sand friction angles from 384 spudcan penetration records in sandy seabeds

No change to previous Abstract! :

The accurate prediction of spudcan penetrations into sand has many consequences to the assessed operability of a jack-up at a given location. Existing standardised approaches for predicting penetrations, such as those provided in ISO 19905-1 (2023), are typically based on general bearing capacity equations using sand friction angles inferred from CPT or laboratory data acquired at the planned installation location. Various approaches are, however, used by practitioners to define the appropriate design friction angle to use as input into the calculations as limited detailed guidance is currently provided in the associated standards.

This study presents the findings from 384 penetration records of spudcans in relatively homogeneous sand soil profiles which have been used to back-calculate the corresponding operative friction angle. The correlation between the operative friction angle and the spudcan diameter, and the sands relative density inferred from CPT data has also been examined and compared with the results and predictive framework proposed by White et al. (2008).

This work provides an extensive dataset and predictive intervals that bound the appropriate friction angle values to be used in conjunction with the classical bearing capacity formulae and associated factors provided in ISO 19905-1 (2023) that should allow for more reliable assessments of both jack-up foundation capacities and stiffnesses, and the potential for seabed risks.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

14 - Spudcans: penetration, extraction, interactions