Stability Assessment of Spudcan Foundation

This paper presents an analysis of the spudcan foundation of jack-up units including preloading, bearing capacity, and the displacement assessment. During the stage of preloading, the settlement of a spudcan in soft clay may be five time as deep as that in sand. The magnitude of sliding capacity, for a pinned condition footing, is mainly affected by the penetration depth. In sand, the normalized maximum horizontal bearing capacity increases with the penetration depth; on the other hand, it is inverse proportional to the depth of the spudcan in clay. When the contribution of the soil moment resistance is considered, a three-stages assessing procedure is recommended: illustration of the configuration of yield surface and environmental forces, the value of yield function with external forces substituted, and the factor of safety of the spudcan. In addition, the results of the assessment may be ambiguous while the different yield functions are employed to analyze the spudcan in soft clay. It should be noted that the additional settlement (plastic displacement) of the footing may occur if the jack-up unit experiences environmental forces beyond its site-specific design.