Using a thin sand layer to ease spudcan extraction in clay
Bibliographic record
Abstract
Difficulties are encountered, in soft clay and silt sediments, during extraction of the spudcan foundations of “mobile” jack-up rigs. This paper reports results from centrifuge model tests undertaken to provide a simple, effective, and practical means for easing spudcan extraction in soft normally consolidated and lightly overconsolidated clay. The tests were carried out on model spudcans of two different geometries typically used in the field. The spudcans were extracted from penetrations of 2∼3 diameters and after an operation period of ∼19 months. The measured pore pressure at the bottom face of the spudcan during extraction process provided insight into the development of suction at the interface between the spudcan base and the underlying soil. The tests were carried out with and without a sand layer placed locally in between the spudcan and the mudline at the onset of penetration. In the field, a gravel layer can be placed by means of a flexible fall pipe system. The presence of a sand layer (with a thickness less than the spudcan tip length) beneath the penetrated spudcan assisted in easing leg extraction difficulties allowing the base suction to be reduced by 73%∼83% and hence the breakout force by 31%∼32%. For a given penetration depth, the installation resistance was also increased by 24%∼26%. This yielded a 15%∼17% reduction of spudcan penetration depth under a given preload and hence the breakout force as much as 50%. Guidelines and cautions for using the proposed measure are provided. Additional advantages of the new recommended method in enhancing the efficiency of the conventional measures of lessening spudcan extraction difficulties are discussed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".