Physical modelling of reinstallation of a novel spudcan nearby existing footprint

The interaction between a spudcan and an existing footprint is one of the major concerns during jack-up rig installation.When a spudcan is located on or nearby an adjacent footprint slope, there is a tendency for the spudcan to slide towards the centre of the footprint, inducing excessive lateral forces and bending moments to the rig. Adverse spudcan displacement could result in an inability to install the jack-up in the required position, leg splay, structural damage to the leg, and at worst, bumping or collapsing into the neighbouring operating platform. This paper reports the results from a series of 1g and centrifuge model tests investigating spudcanfootprint interactions in clay. Three footprint shapes were tested varying depth and diameter. The footprints were generated using a cutting tool, and for the deep vertical walled footprints in the centrifuge, a plastic collar was pioneered to ensure footprint stability before testing. Spudcan loads during reinstallation were measured using a vertical load cell and two bending gauges. A novel spudcan, which was developed to minimise the interaction effects, was also tested and compared the responses with those of a generic spudcan. The results from this study indicated that the novel spudcan has potential to ease spudcan-footprint interactions.