Predicting Spud Can Extraction Resistance in Soft Clay

Abstract

Jack-ups are mobile offshore structures that are frequently relocated to new operation sites. To be relocated, the jack-up footings, known as spudcans need to be extracted from the seabed, using essentially the buoyancy of the hull as extraction force. This operation may be time consuming or even jeopardised if the spudcan extraction resistance is higher than the available extraction force. The maximum extraction (or breakout) resistance consists of suction at the spudcan base, weight of the soil above the spudcan, and soil shear resistance above the spudcan, with the contribution of the suction at the spudcan invert being the dominant component of the breakout resistance. This paper reviews an existing prediction method used to estimate spudcan extraction resistance and proposes an update of some of the input parameters based on insights obtained from a large database of experimental model data on two types of clays and for spudcan embedment up to three diameters.