In the Dutch L6 sector of the North Sea a minimum facility platform has been installed for development of a marginal gas field. The foundation of the asymmetrical support structure consists of three suction caissons. The water depth is about 34 m LAT and the sea bed generally constitutes fine medium to dense sand. In the first metre below sea floor also silt is reported. SPT Offshore has designed and successfully installed the suction caissons offshore, taking pore pressure build-up and consequential soil strength degradation due to irregular loading into account in the design phase. Installation pressures have been predicted using an in-house CPT-based method. The predicted ultimate installation pressures match well with the measured ultimate installation pressures. This paper first introduces the L6-B project characteristics and soil conditions, and secondly presents both the predicted and measured pressure differences for the installation phase.
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