A New Solution to Assess the Required Strength of Mine Backfill with a Vertical Exposure
Bibliographic record
Abstract
Backfilling is commonly applied to aid pillar recovery in open stope mines. The backfill must then remain self-standing in the primary stope when mining an adjacent secondary stope. The design of exposed fill is often based on a solution proposed by Mitchell and coworkers over 30 years ago. Several modifications of this solution have later been reported. These solutions have been partly validated against a few physical model test results, and they have also been compared with numerical simulations. The analyses have shown that these solutions cannot completely capture the response of the exposed backfill, particularly when the required cohesion of the cemented backfill is relatively large. New simulation results presented here indicate that the sliding plane tends to change from planar at small fill cohesion to spoon shaped [three-dimensional (3D)] at larger cohesion. In the former case, the failure mechanism is controlled by shear stress along the sliding plane near the base of the stope; this corresponds well to existing analytical models. In the latter case, however, failure of the backfill is controlled by both shear (near the base) and tensile (near the top) stresses. This feature is not represented by existing analytical models. In this paper, a new analytical solution is proposed for assessing the stability of exposed cemented backfill with a vertical face. An instability criterion is also introduced for estimating the critical strength of side-exposed backfill. Additional numerical simulations are then conducted to validate the proposed analytical solution. The results show that the newly developed solution correlates well with the numerical simulations for representative stope geometry and backfill strength. This new solution is thus regarded as an improvement over existing solutions. Further calculations are made to illustrate the effect of key parameters on the stability of side-exposed fill. A discussion follows on the limitations and effect of various influence factors on the design of exposed cemented backfill.
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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 | 0.001 | 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".