A constitutive model for sand and the analysis of the canlex embankments
Bibliographic record
Abstract
A numerical analysis procedure including a constitutive model for predicting static liquefaction occurrence and liquefaction-induced displacements is presented in this dissertation. The main features of sand characteristic behaviour, as observed from laboratory element tests, are first identified to establish the most important issues regarding static liquefaction analysis. Based on physics fundamentals and elastic-plastic theory, a relatively simple constitutive model capable of capturing sand characteristic behaviour is then proposed. The model has two independent plastic components, a shear mechanism and a volumetric mechanism. The plastic shear mechanism is governed by a hyperbolic relationship between the stress ratio and plastic shear strain, and a flow rule for estimating shear-induced plastic volumetric strain from plastic shear strain. In addition, it has the ability to handle some of the effects induced by inherent anisotropy and rotation of principal stresses. The plastic volumetric mechanism responds to a power law that relates the cap pressure to the plastic volumetric strain induced by compressive loading. The proposed constitutive model is incorporated into a commercially available computer program (FLAC). The code uses a finite differences method that satisfies dynamic equilibrium using a step-by-step time domain procedure and a groundwater flow technique, allowing coupled stress-flow analyses to be performed. The proposed model is calibrated using data from conventional laboratory tests. The model is shown to capture reasonably well the drained and undrained characteristic response of Syncrude sand as observed from element tests, over a range of confining stresses and relative densities. The calibrated model is subsequently used for modelling the Canadian Liquefaction Experiment (CANLEX) embankments that included a field event in which a test embankment was built over a loose sand foundation layer, and a centrifuge test performed on a sand model of the prototype structure. Both earth-structures were planned to induce a static liquefaction failure and their responses characterized by the observed displacements and pore pressures. The proposed constitutive model and numerical procedure used to simulate the CANLEX embankments are shown adequate for performing analysis of sand liquefaction, triggered by rapid monotonic (static) loading. The results from modelling both embankments are in reasonable agreement with the measured responses.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".