BEHAVIOUR OF THE SHORING AND BEDROCK DURING THE EXCAVATION FOR THE BOW
Bibliographic record
Abstract
A 20.5 metre deep excavation with a footprint of 17 700 m2 was completed in downtown Calgary for The Bow, EnCana office complex. The excavation support system required to protect the neighbouring structures was monitored in accordance with Peck’s Observational Method. The maximum observed horizontal deformation of the shoring wall was 153 mm. Geotechnical site investigation indicated that the bedrock was predominantly weak Porcupine Hills Formation mudstones with more competent siltstones and sandstones present in thin interbedded layers. Seismic survey results, point load test analysis, and inclinometer readings during construction indicate that a weak zone of mudstone is present within the bedrock. This zone is responsible for large horizontal deformation and should be considered during design of excavation support. The shear band phenomenon responsible for large deformations in previous downtown excavations was observed to be highly sensitive to excavation activity. Movement of the shear band occurred when excavation activity was 12 m above the layer. Detailed and experienced geotechnical investigation is required to accurately determine the location of potential shear bands. Testing and monitoring results indicate that time dependent swelling in the order of 0.25 to 0.50 %/log cycle be considered during design of structures in the bedrock. A finite element analysis indicates that the large movements observed during excavation are due to the weak zone of mudstone, the shear band layer, and an elevated in-situ stress. The combination of the above factors results in a large zone of influence due to excavation. The estimated horizontal in-situ stress is 1.3 MPa. Further exploration and testing of the in-situ stress is recommended.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".