Role of brittle fracture on swelling behaviour of weak rock tunnels: hypothesis and qualitative evidence /
Bibliographic record
Abstract
Abstract Underground construction in rock prone to swelling behaviour may result in long‐term problems, especially in the invert, if the structure cannot resist swelling pressures. Swelling phenomena are not only a consequence of ground conditions but are strongly influenced by excavation and construction procedures. Evidence of brittle failure observed in the field will be presented and analyzed to prove that brittle failure is the trigger effect of swelling phenomena in shale and clay‐anhydrite rocks. Brittle fractures have also been observed in laboratory swelling tests. Brittle failure can create cracks that form pathways for water, leading to changes in the stress‐state, and as a consequence trigger swelling phenomena. In clay‐anhydrite rock, the swelling pressure is caused by the crystallization pressure of gypsum. The excavation and construction procedures used for the tunnel are a decisive factor for controlling swelling behaviour. Quellvorgänge in Tongesteinen und Ton‐Anhydritgesteinen führen oft zu langfristigen Problemen in Untertagebauten, insbesondere wenn der Ausbauwiderstand der Tragkonstruktion langfristig zu gering ist. Die Quellvorgänge, die besonders im Sohlbereich auftreten, sind nicht bloß eine Folge der Gesteinseigenschaften, sondern werden auch von den gewählten Bauvorgängen und der Tragkonstruktion beeinflusst. Sprödbruchvorgänge wurden in vielen Untertagbauten in Felsgesteinen mit geringer Festigkeit beobachtet. Deren Ursachen werden mit numerischen Modellen analysiert. Sprödbrüche wurden aber auch in Laborquellversuchen in Ton‐Anhydritgesteinen, wo sich Gips bildete, beobachtet. Die unterschiedlichen Beobachtungen werden in einen gemeinsamen Rahmen zusammengefügt. Sprödbrüche führen zur Bildung von Rissen und damit von Wasserwegen. Weiter ergeben sich wesentlichen Änderungen des Spannungszustands um die unterirdische Öffnung, und als Folge dieser Vorgänge werden Quellerscheinungen ausgelöst. In Ton‐Anhydritgesteinen wird der höhere Quelldruck durch den Kristallisationsdruck von Gips verursacht. Der gewählte Bauvorgang muss Sprödbruchvorgänge möglichst vermeiden und ist ein wesentlicher Faktor des aufzunehmenden Quelldrucks und der Quellerscheinungen.
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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) | 0.000 | 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".