Determination of cemented rockfill strength with large scale UCS tests under in-situ conditions
Notice bibliographique
Résumé
Birchtree Mine is an underground nickel mine operated by Vale and located near Thompson, Manitoba. The mining method is sub-level stoping with delayed backfill, with cemented rockfill (CRF) employed as backfill. CRF is composed of sized or un-sized aggregate combined with binder slurry. With proper practice and quality control, CRF offers high strength and stiffness, yielding a stable fill exposure and reducing fill dilution. However, the backfill needs to be economically viable. It is therefore important to adjust and optimize the fill recipe to reduce cost while still attaining the fill strength requirement.The primary goal of the study is to test current CRF practice at Birchtree Mine. The secondary goal is to test adjustments to the current backfill practice to reduce backfill cost. The third goal is to set up a permanent laboratory for the mine to conduct further custom tests as part of a quality control program. To achieve this, the experiment itself needs to be evaluated. Suggestions to improve the experiment, as well as recommendations for future testing, are included in this thesis. The general procedure of the study is described as follows. A literature review was conducted to determine the factors affecting CRF strength. A UCS experiment was then designed based on the literature review. A UCS was designed to conduct the UCS experiment for large scale specimens underground. The experiment was conducted, and the test results analyzed. Finally the experiment itself was evaluated.The factors investigated are cement content, CRF mixing quality, water quality, and aggregate particle size distribution. 27 large scale specimens were prepared and cured under field conditions and tested in the underground lab. The effect of added binder, mixing quality, and grading were determined with respect to the current mine practice taking into account the variation of specimen density. Results for the effect of water quality on CRF strength were inconclusive. An important hurdle the program is the manual preparation of uniform specimens in an underground environment. Consequently, a major shortcoming of the experimental procedure is that specimen particle size distribution (PSD) and moisture were monitored instead of controlled, and specimen uniformity was not achieved with respect to PSD and density. Nonetheless, future tests are recommended, and the laboratory is suitable for the conduct of custom tests. The effects of water content, curing time, and slurry mixing, need to be determined to complete the study. In addition, two-way interactions between moisture content, binder content, and fines content, can be evaluated to optimize the fill recipe.
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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 ».