Investigation of passive failure and deformation mechanisms due to tunnelling in clay
Bibliographic record
Abstract
It is essential to prevent failures at a tunnel face during tunnel construction to protect existing structures and underground utilities. Many studies have investigated active failure in clay, but passive failure is often overlooked. The objectives of this study are to investigate passive failure as well as surface heave and excess pore-water pressure induced by tunnel face displacement in a geotechnical centrifuge. Long-term settlement and dissipation of excess pore-water pressure after passive failure are also investigated. For a tunnel located at a cover to diameter ratio of 2.1, soil in front of the tunnel face is displaced mainly forwards and upwards to the ground surface by the advancing tunnel face. The measured passive failure pressure is closely bounded by the best upper and lower bounds and agrees reasonably well with the cavity expansion solution. For a tunnel located at a cover to diameter ratio of 4.2, a localized failure mechanism is observed. There is a large discrepancy between the measured passive failure pressure and the upper bound solution. Both longitudinal and transverse surface heaves for tunnels located at cover to diameter ratios of 2.1 and 4.2 may be described by two-dimensional Gaussian distributions. The spherical cavity expansion solution appears to overestimate excess pore-water pressure upon passive failure for a tunnel located at a cover to diameter ratio of 2.1. An average of 90% degree of consolidation is reached at time factors of 0.9 and 1.5 for tunnels located at cover to diameter ratios of 2.1 and 4.2, respectively.
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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) | 0.000 | 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 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".