Pore Pressure and Kσ Evaluation at High Overburden Pressure under Field Drainage Conditions. II: Additional Interpretation
Bibliographic record
Abstract
This article is the second of two companion papers studying the effect of a high overburden pressure on the liquefaction behavior of saturated Ottawa sand. A series of four centrifuge experiments were conducted simulating a 5-m prototype layer of this sand in the field, having two relative densities and subjected to overburden effective pressures, σv0′, of ~100 and 600 kPa (1 and 6 atm). The layer was on a rigid impervious base and could drain freely at the top. This was supplemented by undrained stress-controlled and strain-controlled cyclic triaxial tests on the same sand consolidated at 1 and 6 atm. The laboratory undrained overburden pressure factor at 6 atm obtained from the triaxial tests on loose sand, Kσ=0.85, is consistent with the state of practice (SoP), which assumes that Kσ<1.0 and Kσ decreases with σv0′. However, in the centrifuge experiments and σv0′=6 atm, the field Kσ=1.28 for loose sand and Kσ>1.15 for dense sand. The discrepancy is due to more significant partial drainage during shaking in the 6-atm centrifuge models. Although the excess pore pressures at the bottom of the sand layer seem to have been close to undrained in the four experiments, they were much smaller at shallower elevations in the 6-atm tests compared with the 1-atm tests. Further analysis is conducted by evaluation in the four centrifuge experiments of the coefficient of consolidation, cv, during the dissipation phase. This is done using the recorded pore pressure and settlement data. It is concluded that cv was two to four times greater during dissipation in the 6-atm centrifuge tests. The reason is the increase—also by a factor of two to three—of the drained constrained volumetric stiffness of the sand, M′=1/mv, when going from 1 to 6 atm. This finding plus other data from the literature suggest that for a range of sands, layer thicknesses, field conditions, earthquake shaking, and values of σv0′, both M′ and cv may increase proportionally to √σv0′, with the field Kσ>1.0, and with Kσ increasing instead of decreasing with σv0′.
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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 | 0.000 | 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 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".