Experimental investigation of the effect of cyclic loading on spudcan extraction

Abstract

Self-elevating mobile jack-up units have been employed in offshore exploration and development in shallow waters at depths of up to approximately 150 m. Jack-ups are designed to move to a new site after operations are completed. The spudcan footings, which can be embedded up to three diameters deep in soft soil, must therefore be extracted by jacking down the hull into the water and then floating it beyond the neutral draft. This provides the maximum pull-out force to overcome the soil resistance to the jack-ups, but this force may not be sufficient. Problematic cases of this offshore are reported to take up to 10 weeks to extract, a costly exercise for the industry. A method sometimes used ..