The Effects of Displacements on the Stability of Jackup Spud-Can Foundations

The stability of jackup spud-can foundations is usually assessed on the basis of ultimate bearing capacity formulae that do not take into account the effects of spud-can displacements. This paper describes a nonlinear load-displacement model that has been developed to investigate the importance of this effect. The model has been calibrated using finite-element analyses. Examples demonstrate the impact of displacements on foundation stability. The paper shows the importance of including displacement considerations and of evaluating the jackup foundation system behaviour rather than that of individual spud-cans, the assessment of moment-fixity and the determination of the load transfer between the spud-cans of a jackup. The paper includes sufficient information to allow development of the nonlinear model.