Design and Implementation of Innovative, Openable, In-Trench Rockfall Catchment Fences for Improvement of Worker Safety in Steep Slope Pipeline Construction
Bibliographic record
Abstract
ABSTRACT: This paper presents the implementation of an in-trench rockfall catchment system on a steep slope in the Coast Mountains of British Columbia. Using a combination of drone photogrammetry, digital geological mapping, change detection tracking, and numerical rockfall modeling, Stantec identified a rockfall hazard presenting a high risk to the workers and equipment in the trench downslope. Using numerical modeling and field observations of rockfall trajectories, the construction team sought to design a rockfall mitigation system to control the rockfall hazard while satisfying a tight construction timeline and the need for an openable, gate-like design. The solution was a series of 100 kJ rock catchment fences- each 3 m high and spanning the 5 m wide trench, secured to the granodiorite trench walls with grouted dowels. The gate-style rockfall mitigation design is, to the team's knowledge, the first of its kind to be implemented in pipeline construction. The design was successfully used throughout the approximately 6-week period of pipe installation on the slope, marking a successful solution to a unique construction challenge. 1. BACKGROUND Coastal GasLink is a 670 km (420 mi) long pipeline which will transport natural gas from Groundbirch to Kitimat, British Columbia, across some of the most rugged alpine terrain in Canada. The approved Coastal GasLink route was determined by considering Indigenous, landowner and stakeholder input, the environment, archaeological and cultural values, land use compatibility, safety, constructability, and economics. The slope of interest for this paper is within Section 8 West of the pipeline alignment- a 13 km (8 mi) long span, fraught with geohazards, across the highest passes of the Coast Mountain Range, see Fig 1. Further details of the Coastal GasLink are provided in Coastal GasLink (2023). The slope designated Steep Slope 6B (SS6B) by the project team is the focus of this paper, and the site at which the gate-style rockfall catchment fence system was implemented. SS6B is 250 m (820 ft) long and is sloped at approximately 30 degrees. It is located near the junction of two converging glacial valleys in the headwaters of the Kitimat River. At an elevation of 860 m (2820 ft), SS6B is approximately halfway between the glaciofluvial and colluvial debris in the valley bottoms and the 2000 m (6500 ft) high, glacially-eroded mountain peaks which surround both valleys.
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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 | 0.001 | 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 | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".