RR289 - Guidelines for jack-up rigs with particular reference to foundation integrity
A jack-up rig is typically used at a dozen or more sites during its service life. It can therefore be expected to encounter a range of water depths, environmental load conditions and soil types. For each candidate site, an assessment is conducted to determine the suitability of the unit for the site and to provide data for the installation operation. Such assessments are normally conducted using the SNAME Technical and Research Bulletin 5-5A.
This report addresses the foundations of jack-up rigs, with the overall objective of determining current knowledge and assessment practices. An exhaustive literature search was initially conducted to establish a database of knowledge. A review of the collated data identified case histories of foundation problems, and in turn the major challenges associated with foundation assessment. Various foundation topics (eg punch through, bearing and sliding capacity, existing footprints, rack phase difference, etc.) were then examined in depth and recommendations made. In many cases the recommendations are a reaffirmation of existing guidance; in other cases some improvements to the existing guidance are suggested. In the case of rack phase difference, there is no guidance in SNAME and therefore specific provisions have been developed herein.
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