In situ properties and liquefaction potential of cemented paste backfill
Bibliographic record
Abstract
Mercury intrusion porosimetry as well as semi-qualitative image analysis techniques such as scanning electron microscopy, microCT and visual analysis software were used to develop an understanding of the structure developed in field CPB in both the macro and micro scale. Standard oedometer consolidation testing with a modified loading rate was used to investigate the interrelationship of loading rate, which simulates rate of paste accumulation in a stope and the hydration of binder of the paste. The results show that the structure that develops is sensitive to both the binder content of the CPB and the rate of paste accumulation. Cemented paste backfill (CPB) has gained increasing popularity in the last 5 to 10 years and is used routinely in several mines. However, most of the CPB designs are based on laboratory prepared CPB material properties and there is growing awareness that the field CPB may be different from the laboratory prepared material. A field based investigation quantified the extent to which the field material differs from laboratory material. Not only is the field material more heterogeneous than expected, but on average it has a higher void ratio and a lower degree of saturation. These differences impact the performance of the field material. Numerical analysis using FLAC 3D was undertaken to show the influence of the field condition on the stability of the CPB. This research provides practical recommendations for industrial application and provides a framework for further investigation of CPB. Several research projects arising from this initial work are already underway through the Lassonde Institute at the University of Toronto, and several more are at the proposal stage. Static and dynamic liquefaction testing of early age CPB showed that liquefaction due to self-weight alone is unlikely but that blasting too close to the CPB can mobilize the material. Practical recommendations such as limiting blasting in proximity to early age CPB and cordoning off vulnerable areas during the critical initial 24 hr period that the paste is vulnerable to dynamic liquefaction. The cyclic liquefaction results are believed to be the first reported for cemented paste backfill.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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".