Excavation effects on pile behaviour and capacity
Bibliographic record
Abstract
Pile load tests are often carried out at the ground surface, prior to a basement excavation. The effects of stress relief due to excavation on pile stiffness and capacity are not considered. In this paper, a series of centrifuge model tests in dry sand are reported to investigate pile behaviour with and without simulating excavation effects. In-flight load tests on 10 instrumented single piles were carried out both at the ground surface and at the formation level after excavation. The effects of distinct pile–soil interfaces on pile behaviour are studied. The test results show that the capacity of a low-friction pile (a pile with a nondilatant interface) subjected to excavation is reduced by 16%–20% when different failure criteria are adopted. The reduction is due to a decrease in shaft resistance, which is proportional to the magnitude of stress relief resulting from excavation. The angle of friction mobilized at the ultimate state is the same for piles with and without stress relief. For a high-friction pile (a pile with a dilatant interface), however, capacity of the pile subjected to stress relief increases by 22%–44%. This results from an increase in shaft resistance, due to the higher magnitude of dilation of the interface soil when stress relief is induced by excavation. The governing mechanism of shaft resistance for a high-friction pile is distinct from that for a low-friction pile.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".