Manhole Cover Displacement Caused by the Release of Entrapped Air Pockets
Bibliographic record
Abstract
Stormwater systems undergoing rapid filling may present a variety of operational problems, one such being the displacement of manhole covers, which can threaten both traffic and pedestrians.There are scarce documentation and few measurements of flow conditions in rapidly filling stormwater systems, and it is speculated that air pressurization within manholes leads to such displacements.There can be different causes of air pressurization in manholes, among which is the release of entrapped air pockets through water-filled shafts.Research has indicated that such releases will result in the displacement of the free surface within these manholes, which in turn may create conditions for air to develop enough pressure to overcome the weight of a manhole cover and displace it.This paper presents results from an ongoing computational fluid dynamics (CFD) simulation of air pocket release in shafts with limited ventilation at the cover.Results indicate that releases of large air pockets can create pressure surges that far exceed the threshold for manhole cover displacement, and that pressure rise can occur within a few seconds following air admission into the shaft.The ultimate goal of this investigation is to provide better guidance for the management of air in junctions within stormwater systems, and to prevent operational issues that are linked to air-water flows.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".