OXYGEN DIFFUSION AND CONSUMPTION IN UNSATURATED COVER MATERIALS
Bibliographic record
Abstract
RÉSUMÉ: Dans plusieurs problèmes de géotechnique environnementale, les ingénieurs doivent analyser des situations d'écoulement simultané d'eau et de gaz. C'est typiquement le cas lorsque des couvertures en sol sont conçues pour des sites d'entreposage de rejets. Étant placés bien au- dessus de la surface phréatique, les matériaux de recouvrement sont non saturés, et ils peuvent permettre à des composés gazeux (tels que l'air et le méthane) d'entrer ou de s'échapper du site. Comme c'est le cas avec l'eau, le flux de gaz doit habituellement être contrôlé par le recouvrement. Une application particulière à cet égard concerne les couvertures construites pour limiter le flux d'oxygène vers les résidus miniers sulfureux, qui peuvent générer un lixiviat acide. Dans cet article, les auteurs présentent une a pproche pour évaluer ce flux et les paramètres de contrôle, incluant le coeffi cient de diffusion effectif D e et le coefficient du taux de réaction (ou de consommation) K r . Un procédé expérimental pour la mesure simultanée de ces deux paramètres en laboratoire est décrit, et une procédure d'in terprétation avec quelques résultats d'essais sont présentés. Des solutions analytiques sont de plus développées pour calculer le flux d'oxygène à travers des systèmes de recouvrement. Ces solu tions sont comparées aux résultats obtenus d'un traitement numérique des lois de Fick modifiées . Diverses applications spécifiques de la méthode de conception des barrières à l'oxygène sont présentées et discutées. ABSTRACT: In many environmental geotechnique problems, engineers must analyse situations where water and gas can move simultaneously. Such is typica lly the case when soil covers are designed for waste disposal sites. Being located well a bove the phreatic surface, cover materials are unsaturated and may allow gaseous compounds (such as air and methane) to flow in or out from the disposal facilities. As is the case for water, the flow of gas must usually be controlled by the cover. A particular application in that rega rd relates to covers built to limit oxygen flux to reactive sulphidic tailings, which can be the source of an acidic leachate. In this paper, the authors present an approach to evaluate the oxygen flux with the controlling parameters, including the effective diffusion coefficient D e and the reaction (consumption) rate coefficient K r . An experimental procedure to determine these two parameters simultaneously during laboratory experiments is described, and sample results are presented with the proposed interpretation. Analytical solutions are further developed to calculate oxygen flux through cover materials. The proposed solutions are compared to calculation results ensuing from a numerical treatment of modified Fick's laws. A vari ety of specific applications of the method for designing oxygen barriers are also presented and discussed.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".