A New Generalized Solution for the Required Strength of the Three Types of Cemented Mine Backfill
Bibliographic record
Abstract
ABSTRACT: Cemented mine backfills (Cmb) are widely used in underground mining operations. Indeed, for primary and secondary stoping methods, Cmb provides secondary ground support. During secondary stoping, at least one face of the backfill may be exposed, and a failure can occur if the backfill is not strong enough. To ensure the stability of Cmb mass placed in an underground opening with one or more exposed faces during blasting, a given backfill minimum strength is required. The standard practice for assessing the minimum strength of the Cmb is to conduct uniaxial compressive strength (UCS) tests. The minimum required UCS depends on the number of exposed face(s). In the mining industry, a simplified design method is used based on the confined block model. However, most available models do not allow all scenarios to be taken into consideration (e.g., several exposed faces, rockfill, very large stopes, etc.). This paper provides a new generalized 3D solution of the UCS design required for the three main types of mine backfill (i.e., hydraulic fill, paste fill and rockfill) that a designer can use in the design process. 1. INTRODUCTION Mine backfills are widely used in underground mines in order to dispose waste rocks and tailings from mining operations and to provide temporarily and secondary support during the ore extraction. There are three types of mine backfill that are used in underground backfilling: cemented hydraulic backfill - CHF (or hydraulic fill – HF or slurry fill - SF), cemented paste backfill – CPB (or paste fill - PF), and cemented rockfill (CRF). Nowadays and with technological development, the mines are deeper and deeper (e.g., >2.5 km) for a total extraction such as open stoping, and the stresses induced are very high. But, to ensure the stability of the backfill mass with an exposed face during open stoping, minimum strength is required. There is no standard method of the design of required backfill strength for underground mining since it is a relatively recent technology. The practical observations and the experience of the designer are used in most cases. However, there are rules and principles that should be followed for every design case. First, the method and the environment of the extraction should be identified in order to determine the function of the backfill. The mechanical design of the CPB requires an assessment of the minimum uniaxial compressive strength (UCS) of the backfill, depending on its function (e.g., Belem & Benzaazoua, 2008). For primary and secondary stoping methods, backfill provides secondary support while extracting the neighboring ore (e.g., Cai, 1983; Annor, 1999). During secondary stoping, at least one face of the backfill mass may be exposed, and a risk of failure or instability due to gravity loading can occur if the backfill is not strong enough.
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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".