Stress-wave Induced Fracture in Rock due to Explosive Action
Bibliographic record
Abstract
Blasting is a complex phenomenon and many parameters affect the outcome of a blast. The process of rock fragmentation by blasting is not well understood yet. Therefore, as a first step, blast-induced dynamic fractures must be studied under highly controlled conditions. The whole cycle of conducting a series of laboratory-scale blast, analyzing the results, and using them to test the validity of an advanced numerical code is reported in this thesis.\nInitially, the respective contributions by both shock energy and gas energy fractions in an explosive in the blasting process are explained. Then, microstructural, physical and mechanical properties of Laurentian and Barre granites as the selected rock types are investigated.\nExplosively driven fractures in a blast are controlled by rock and explosive properties, coupling media and coupling ratio. Sample geometries, types of explosives and coupling media used in the experiments are explored in the next step. In order to isolate the effect\niii\nof shock energy from the gas energy in explosively driven fractures, copper liners were installed in the blast holes to prevent gas penetration into the shock induced cracks. The aim of the experiments was to study exclusively the nature of shock-driven fractures, and to contain the dynamic fractures within the samples and avoid sample fragmentation. At the same time and in order to investigate the stress field as a function of distance from the borehole, pressure gauges were installed in the samples. The measured pressures were used in a numerical-experimental procedure to estimate the attenuation properties of the rocks. Blasted samples were cut and impregnated with a mix of epoxy and fluorescent dye. Next, dynamic fracture patterns were highlighted using a strong ultraviolet source. After taking photographs, fracture patterns were manually mapped and crack densities were calculated at different depths and distances from the boreholes. The parameters that affect the development of dynamic fracture patterns are also discussed and relation between crack densities and pressures applied by explosives are investigated.\nFinally, the dynamic fracture patterns and measured pressures will be used for calibrating the selected equation of state, strength and failure models implemented in AUTODYN. Governing equations, the procedure for obtaining the model constants, applicability of the selected model for predicting the blast experiments and its limitations are discussed in detail.
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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 | 0.000 |
| 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 | 0.000 | 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".