Ridge Keel Forces on Vertical Structures
Bibliographic record
Abstract
Abstract In northern regions, ice forces, or actions, must be considered in the design of structures such as light piers, bridge piers, and offshore platforms. Estimates of ice forces in Canadian waters are usually obtained by consulting design standards such as those developed by the International Organization for Standardization (ISO) and the Canadian Standards Association (CSA). These design standards draw on available analytical formulae. Field measurements are available from several sources that suggest reasonable agreement with analytical results for simple cases involving wide structures. One of the remaining uncertainties in estimating design loads, however, is the contribution of force imposed below the waterline due to unconsolidated keels of ice ridges. Only cursory guidance is provided by the standards associations and their analytical design equations. Close inspection of those formulae show that force estimates can become excessive in situations where the expected keel depth is great compared to the designed structure width. Such scenarios would be expected in offshore oil and gas operations where drilling risers, jack-up legs, and even jacket structures may be exposed to ice ridges. The present work examines available approaches for evaluating ridge keel forces, including passive pressure calculations. The processes of ice rubble failure and the corresponding stress distributions are considered in the context of classical soil mechanics applied in geotechnical engineering. Design standards are also used to calculate ice forces for a range of ridge keel properties, keel geometries, and structure design widths. Field measurements from the Norströmsgrund lighthouse and the offshore Molikpag caisson are then examined and compared to the forces obtained using these approaches. The authors conclude that the shape factor adopted in ISO 19906 plays an important role in calculations considering narrow structures and deep keels. It is also shown that the sensitivity of ridge keel load calculation to geometric factors varies considerably with structure width. Furthermore, an absence of real world data from ridge keel interactions with very narrow structures precludes validation of present models in these situations and should be the focus of data collection and model refinement.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".