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

ABSTRACT

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.

KEYWORDS:

• Jack-up rig
• ‘Step on the footprints’
• lateral sliding
• bending moments
• rack phase difference

Acknowledgement

Jie Gao: Conceptualisation, Methodology, Software, Formal analysis, Writing-Original Draft. Lindong Fan: Software, Validation, Investigation. Jianbo Li: Resources, Writing-Review & Editing. Ye Yuan: Software. Junpeng Liu: Validation, Investigation. Menglan Duan: Writing-Review & Editing, Funding acquisition.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Key Research and Development Plan of China (grant number 2016YFC0303708); and the National Natural Science Foundation of China (grant number 51709164). The support is gratefully acknowledged.