Effect of Field Drainage on Seismic Pore Pressure Buildup and Kσ under High Overburden Pressure
Bibliographic record
Abstract
This paper studies the effect of a high effective overburden pressure [σv0′= ∼600 kPa (6 atm)] under two drainage conditions on the field liquefaction behavior of saturated Ottawa sand. A series of eight centrifuge experiments with relative densities Dr=45% and 80% and base shaking are considered that include a 5-m saturated sand layer under a pressure of either σv0′= ∼100 kPa (1 atm) or ∼600 kPa (6 atm). Four of the tests had single drainage at the top of the layer (SD), whereas the other four tests had double drainage (DD) at top and bottom. The four SD test results had been reported before, whereas the four DD tests are new. A novel centrifuge technique was developed to achieve the double-drainage boundary condition of two pervious boundaries at the top and bottom of the sand layer, using a geocomposite at the bottom. Measured responses are compared at the same σv0′ between SD and DD tests having the same input acceleration, as well as between SD and DD tests where the shaking induced a similar maximum excess pore pressure ratio (ru)max≈0.8. These comparisons include acceleration time histories, excess pore pressure time histories and profiles during and after shaking, and stress ratio and shear strain time histories. Comparisons between corresponding tests at ∼100 and ∼600 kPa (1 and 6 atm) revealed significantly more partial drainage at ∼600 kPa (6 atm) than at ∼100 kPa (1 atm), with even more significant variation in excess pore pressures in the DD than in the SD tests. Best estimates of field overburden pressure correction factors at ∼600 kPa (6 atm), Kσ were obtained, were obtained from the centrifuge results with two independent methods for a failure criterion of (ru)max=0.8. Those Kσ=1.2–1.3>1.0 for both SD and DD drainage conditions due to the significantly lower compressibility of the sand at ∼600 kPa (6 atm). The results further emphasize the important role partial drainage may play in the field during shaking at high σv0′ on the excess pore pressures and values of Kσ.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".