Spudcan slip prediction of jack-up rig near the footprint: a coupled RPD-moment based solution

When the jack-up rig is reinstalled near the old footprints, the spudcan will slide laterally and generate a bending moment at the bottom of the jack-up rig's leg due to the existence of the old footprints, endangering the jack-up rig's operation safety. The maximum bending moment is chosen as the input condition for spudcan slipping in the truss three-legged jack-up rig's model based on the results of square spudcan stepping on the footprints. At the maximum bending moment, the critical slip distance and its corresponding critical rack phase difference (RPD) of the verified model in different slip directions are obtained. Simultaneously, the effects of different bending moments on the critical transverse slip distance and critical RPD are analysed in different directions. As a result, the RPD real-time monitoring value on the top platform can be used to predict the spudcan's lateral slip distance. It is useful for platform designers and operators when jack-up rigs reinstall near existing footprints.