Moment Fixity of Spudcan Footings

Prof. Guy Houlsby, Dr Chris Martin and Dr Mark Cassidy

Both experimental and numerical work has been completed to develop new methods of understanding the interaction between the spudcan foundation of a jack-up unit and both clay and sand soils. Particular attention was paid to the prediction of moment fixity, which is of importance to the assessment of jack-up units. New analytical models have been developed based on work-hardening plasticity theory. Experimental work was used to verify the new theories, and to provide direct evidence of the shape of the yield locus and other features of the plasticity model. The experiments made use of a computer-controlled rig which can apply any displacement path to a model spudcan. Loads and displacements were monitored. By carrying out a carefully controlled series of tests at different depths of embedment, the behaviour of the spudcan, and the changes of the response with depth, can be determined. The results of the work are being used to assess the reliability of current practice in assessment of jack-up units.