Stress Ratios in Entire Mine Stopes with Cohesionless Backfill: A Numerical Study
Bibliographic record
Abstract
Evaluation of stress states in backfilled mine stopes (or similar openings), using arching theory, can be largely impacted by the value selected for the earth pressure coefficient, K = σ′h/σ′v. Recently, the current study’s authors addressed the debate about the value of K near the opening center, based on Rankine’s active coefficient (Ka) and at-rest coefficient (K0). Here, stress ratios in vertical backfilled stopes are numerically assessed (in two dimension, 2D), considering both the independent and related backfill internal friction angle (ϕ′) and Poisson’s ratio (ν). Emphasis is placed on the backfill state near stope walls, where local rotation of stresses occurs, so the coefficient (K) and principal stress ratio, Kps (= σ′3/σ′1), should be distinguished. Parametric analyses indicate that values of K and Kps depend on the position and the relationship between ϕ′ and ν. Near the opening center, K (= Kps) is close to Ka when ν or ϕ′ is below a critical value; otherwise the value approaches K0, defined from ν. Near both walls, Kps is always close to Ka, while K is near K0 for related ν − ϕ′ cases and depends on their respective values for independent ν and ϕ′. Additional simulations conducted with interface elements indicate that the stress ratios near the opening center line are insensitive to interface roughness and are almost identical to values obtained without interfaces, but the stress ratios near walls may change for less rough or smooth interfaces.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".