Forms and sand transport in shallow hydraulic fractures in residual soil
Bibliographic record
Abstract
Four sand-filled hydraulic fractures were created at a depth of 1.5 m, and the vicinities of the fractures were excavated and mapped in detail. All the fractures were shaped like slightly asymmetric saucers between 4.5 and 7.0 m across that were roughly flat-lying in their centers and curved upward to dip between 10° and 15° along their peripheries. Three different colors of sand were injected in sequence to trace the relative ages of the sand in the fracture. The first sand to be injected remained in the vicinity of the injection casing, whereas the last sand moved rapidly to the leading edge. Sand transport occurred through localized, channel-like pathways that extended from the injection casing and then branched into multiple paths as they approached the leading edge. At least four branching pathways of different ages were identified in one fracture, suggesting that this represents a fundamental mechanism of sand transport in these shallow fractures. A theoretical model was developed by adapting Franc2d, a code well-known in structural mechanics, to predict the propagation paths of curved hydraulic fractures at shallow depths. The model predicts fracture forms that are remarkably similar to those in field exposures when properties typical of field conditions are used.Key words: hydraulic fracture, field test, mechanics, modeling.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".