Instrumented Pull Test Results in Grouted Split Sets, and Its Comparison with Non-Grouted Test Results in an Underground Manganese Mine – Corumbá/MS - Brazil
Bibliographic record
Abstract
ABSTRACT Rock mass friction stabilizers, commonly called Split Sets, were introduced in the metal mines of the United States and Canada in the early 70s. Split Sets can provide support due to friction between the anchor and the rock surface of the boreholes. As Split Sets are inserted in boreholes with slightly smaller diameter than the diameter of the retainers, the radial force is generated by the compression of the anchor by the drill wall, ensuring its efficiency by friction in this contact interface. In order to increase the maximum load capacity of Split Sets, some mining companies opt for grout injection after the installation of the anchors. The present study presents the results of instrumented pull tests performed in Grouted Split Sets and its comparison with the result of tests performed in Split Sets without the application of cement, in an underground manganese mine. A total of 72 tests were performed in 3 different mine locations, with distinct roof geological characteristics, and the results showed an increase of up to four times the initial strength without the application of grout, considering the best scenario. INTRODUCTION Split Sets can provide pressure support due to friction between the anchor and the rock surface of the holes. These were the first types of friction anchors to be used and still are the most widely type operated in underground mining. Split Sets consist of steel tubes sectioned longitudinally, and a steel ring fixed at its lower end, able to apply force to a steel plate that transfers the load to the surface of the excavation. As the Split Sets are inserted in boreholes with slightly smaller diameter than the diameter of the retainers, the radial force is generated by the compression of the tube over the drill wall, ensuring its efficiency by friction in this contact interface (Komurlu and Demir, 2019). According to Komurlu and Demir (2019) the length of the Anchor is an important parameter for load capacities of support with Split Sets. Load capacity increases with bigger length of anchor. In addition to the length of the Split Set, other parameters have a great influence on the efficiency of this type of anchoring. A factor of great impact on the maximum load supported by the Split Set is the drilling diameter. When anchor of the same characteristics and dimensions are used in different diameters of perforation, we realize that there is a tendency to obtain higher maximum loads using smaller diameters, as shown in figure 1 (Tompson et al. 1999).
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 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".