Assessing the strength and bearing capacity of tailings for oil sands reclamation
Notice bibliographique
Résumé
Reclamation of oil sands mines in northern Alberta presents a significant challenge for mine operators, particularly the reclamation of tailings deposits that are produced by the mine waste stream. A proposed approach to reclaiming tailings deposits as upland or wetland landforms is capping which involves placing material such as tailings sand or petroleum coke on the tailings surface. Critically, the underlying tailings deposit must have sufficient strength, density, and bearing capacity to support the cap as well as the equipment and personnel required to place it. Otherwise, equipment can “punch through” the cap into the underlying tailings, posing a significant hazard for the equipment and operator. Clay minerals play a significant role in the challenging geoenvironmental behaviour of oil sands tailings, and therefore must be considered in the design and implementation of capped deposits. A well-established method for quantifying clay behaviour in geotechnical engineering is the Atterberg limits, which define the water contents for which clay will exhibit plastic behaviour. Atterberg limits can also be used to develop correlations between the liquidity index and remoulded undrained shear strength. Atterberg limits are currently used to characterize oil sands tailings, however, there are unique challenges to applying existing measurement methods to these materials compared to natural soils. There is also no relationship between remoulded strength and liquidity index for strong, dense tailings that are being targeted as capped deposits, though relationships exist for natural soils and fluid, low-density tailings. Current practice to evaluate deposits is to predict bearing capacity from peak undrained shear strength and apply an appropriate factor of safety. A laboratory testing program and a review of existing published data was undertaken to investigate the Atterberg limits, strength, and bearing capacity of oil sands tailings. A series of Atterberg limits tests in which material properties, preparation method, and test procedure were varied were completed. It was determined that these factors influenced the measured Atterberg limits, though it was challenging to determine the effect of individual factors compared to the quantified variability of the tests. Air-drying the tailings from above the liquid limit to the plastic limit at low temperatures is proposed as a standard preparation method as this preserves the properties of the as-received tailings and is straightforward to perform. Atterberg limits and strength measurements determined in the test program were also used to determine a mathematical correlation between the remoulded strength and liquidity index of high-density tailings. Model footing tests at the benchtop scale demonstrated that existing methods of predicting bearing capacity from peak strength are appropriate. The sensitivity ratio was used to apply the proposed correlation between remoulded strength and liquidity index to the model footing results and propose a new method for predicting bearing capacity from index properties. The results of this research program support the idea that index properties such as Atterberg limits can provide a cost-effective method for long-term monitoring and the preliminary design of capped deposits.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».