Shear Strength of Sand-Gravel Mixtures: Laboratory and Theoretical Analysis
Bibliographic record
Abstract
Many natural slopes and rock fill structures are made of a mixture of dispersed rock fragments (gravel) and sand-size particles. To analyze the stability of such structures, the shear strength of the sand-gravel mixtures is needed. For this purpose, direct shear tests were carried out on mixtures of Ottawa sand (d50 = 0.59 mm) and fine gravel (d50 = 5 mm). The shear strength of the sand and the sand-gravel mixtures was measured under two normal stresses. These normal stresses were equal to 52 kPa and 103 kPa. During the tests, the initial void ratio of the matrix was maintained relatively constant at a value equal to 0.8. The concentration by weight of the gravel in the mixtures tested varied between 0 and 30%. These concentrations by weight correspond to a concentration by volume equal to 0 and 19.3%. The results of the direct shear strength tests indicated that the angle of internal friction improved with an increase in the concentration of the gravel in the mixtures. The angle of internal friction was equal to 40.40 for the sand alone. The friction angle increased to 46.90 for the sand sample with a concentration of gravel by weight equal to 20% (12.1% by volume). It was determined that the shear strength of the sand-gravel mixtures can be determined from the shear strength of the sand matrix alone and the concentration by volume of the gravel in the mixtures if one uses the equation: Sc = Sm (1+2.5 C). In this equation, Sc is the shear strength of the sand-gravel mixture, Sm is the shear strength of the sand matrix alone, and C is the concentration by volume of the gravel in the mixture. However, the validity of the equation has not yet been determined to be general and has only been shown to apply to the type and size of materials, stress conditions, and type of equipment used in the reported testing program.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".