Effect of Cylindrical THF Hydrate Veins on the Undrained Behavior of Fine‐Grained Soils
Bibliographic record
Abstract
Abstract Gas hydrate filled fractures and veins readily occur in fine‐grained deep water marine sediments that increase sediment strength and restrict sediment consolidation. Subsequent hydrate destabilization can dramatically reduce sediment strength, which may lead to slope failures. To investigate the undrained behavior a series of consolidated undrained (CU) triaxial tests were carried out on fine‐grained soils containing cylindrical tetrahydrofuran (THF) hydrate veins of varying diameter to mimic naturally occurring hydrate‐bearing clays. Axial compressions tests on stand‐alone hydrate veins showed brittle failure with axial stresses reasonably independent of vein diameter and confining stress and thought related to development of bending stresses and tensile cracking. Reduced axial strain rates led to ductile behavior, potentially suppressing tensile crack development, resulting in slightly higher failure stresses. CU shear tests on hydrate‐bearing specimens showed increasing strength and stiffness with increasing vein diameter and confining stress, although the impact of confining stresses reduced for the largest diameter veins. Using a Mohr‐Coulomb failure criteria, increased strength was associated with increase in cohesion and reduction in friction angle. The enhanced strength would reduce consolidation processes that would lead to sediment instabilities if the hydrate was destabilized. However, for larger diameter veins, increasing lateral stresses from the soil reduced buckling stresses with significant plastic deformation of the THF veins being observed at the end of tests, suggesting a strain rate dependent behavior. Further research is required to fully understand this behavior and its impact on sediment consolidation to fully consider the relationship between hydrate dissociation and sediment instability.
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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".