In situ behaviour of cemented hydraulic and paste backfills and the use of instrumentation in optimising efficiency
Notice bibliographique
Résumé
Better understanding of in situ backfill behaviour can allow mines to optimise backfilling efficiency. To this end, a significant quantity of fieldwork has recently been conducted by University of Toronto (U of T) and Mine Design Engineering (MDEng.), focused on in situ measurements in cemented paste backfill. Using these ‘production friendly’ instrumentation approaches, new fieldwork data from two of Vale’s Canadian operations are presented, to demonstrate how instrumentation can be applied to better define the behaviour of cemented hydraulic backfills. Instrumentation consists of clusters of total earth pressure cells, piezometers (for pore pressure) and thermistors that are placed remotely in open stopes, and mounted on barricades. Backfilling with cemented hydraulic fill requires consideration of drainage and potential segregation affects, which are not associated with paste. In situ data demonstrates the transition of the backfill from a fluid to soil-like material at various locations in backfilling stopes. Within a relatively coarse grained (i.e. sand) cemented hydraulic fill, this transition occurred relatively quickly (after three hours). For a sand and tailings blend of cemented hydraulic fill however, the hydrostatic loading condition persisted for between 12 and 24 hours. During backfilling, this information, combined with barricade pressure data, was used to optimise requirements for the post-plug cure period, saving up to three days of stope cycle time. The measurements in hydraulic fill are contrasted with previous fieldwork data from cemented paste backfill. Strength gain mechanics differ between the fill types, through the requirement for drainage in hydraulic fills, whereas cement content and self-desiccation mechanisms appear to dominate in situ measurements in paste. Hydraulic fills exhibit particle size segregation which results in spatial variation in cement content, and so spatially distinct pressure and temperature responses for the interpreted coarse and fine grain zones were measured. A measured low temperature zone was interpreted to represent a coarse grain size fill with an at rest earth pressure coefficient similar to that of a dense sand. A high temperature zone was interpreted to represent a fine grain size fill which features higher cement content. The significantly greater temperature measured in the binder-rich areas are thought to induce ‘thermal expansion’ generated pressure increases. This work demonstrates the potential for instrumentation to feature as part of a considered quality control policy (that includes barricade construction and drainage checks) to safely optimise backfilling efficiency.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 tête enseignante, 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 ».