Toppling failure in the Marmot Vertical Limb at Quintette Coal Ltd., Tumbler Ridge, British Columbia
Bibliographic record
Abstract
Two years in a row Quintette Coal Ltd. had a toppling failure occur on the North Wall in the Marmot Vertical Limb. The wall has an overall angle of approximately 50 degrees, and the stratigraphy, consisting of poor quality sandstone and shale, is dipping almost vertical. The July 27th bench scale toppling failure, was initiated by high pore pressures generated in tension cracks. The September 18th toppling failure was a multi-bench failure, which had been developing for over a year. Although water pressures did not initiate failure, transient water tables contributed to the overall instability. Both failures were the result of poor wall design and blasting damage. This thesis presents the background material, the mine and monitor method developed and the back analysis of the failure. The areas researched include: regional and local geology, structural geology in the Vertical Limb, mine development, the groundwater conditions encountered, the blasting practices used, the artificial support systems installed and the monitoring network established. The analysis of the failure used the Distinct Element Method developed by Peter Cundall. This method is a recognized discontinuum modelling approach, which is used to model jointed media subjected to quasi-static or dynamic loading. The method has been compared to the Limit Equilibrium Analysis proposed by Goodman and Bray in 1976, but most of the work involving UDEC (Universal Distinct Element Code) has centred around tunnel design and support requirements, rock reinforcement, fluid flow through a jointed media, dynamic loading and thermal-mechanical modelling. In this thesis the rock mass is analyzed as a series of rigid blocks, which are subjected to gravitational forces. The purpose of UDEC is not to design pit walls or better dams, but rather to be used as a tool to better understand how a jointed rock mass behaves under static and dynamic loads.
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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 | 0.001 |
| Science and technology studies | 0.004 | 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) | 0.002 | 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".