Variable suction and its effect on stability at the Ripley Landslide near Ashcroft, British Columbia
Bibliographic record
Abstract
The high concentration of landslides south of Ashcroft in the Thompson River valley of British Columbia, Canada has periodically affected operation and maintenance of track infrastructure for both of Canada’s primary railway operators as far back as written historical records exist. Historical site investigation and study of the landslides in the region previously identified the primary controlling factors for landslide displacement. However, the arid climate of the region causes a large portion of the landslide head scarps to be unsaturated and minimal study has focused on the consequences of climatic variation that drive soil water content changes in the vadose zone. The research program focused on a heavily instrumented and recently active landslide in the Thompson River valley, known as the Ripley Landslide.\nThe study collected soil samples for unsaturated material characterization, instrumented and monitored the near-surface soil water content changes, compared these changes to annual displacement trends, and developed a 3D modelling framework to establish the impact of variable soil suction on stability at the Ripley Landslide. The research methodology began with a field program to install matric suction sensors, including low-cost dataloggers. Soil samples recovered from the borehole investigation were used to determine the unsaturated material properties. Collection of meteorological observations over several years were interpreted in relation to displacement rates. Records from historical borehole investigations, geophysical surveys, and instrumentation monitoring were incorporated into a 3D model of the Ripley Landslide.\nInvestigation during the research program provided a detailed description of the upper till unit present at the Ripley Landslide. Soil classification and behaviour estimates provided inputs that were vital to the stability model. Interpretations from matric suction monitoring and climatic variables documented their influence on historical displacement rates. New investigation techniques (such as ERT, SMD, and stable water isotopes) provided further evidence for increased soil water content in the head scarp tension cracks that contributed to deeper infiltration. 3D limit equilibrium and 3D finite element models estimated groundwater movement, within a set of known criteria, and determined that matric suction contributed at least 4% to the overall factor of safety. Meanwhile, the river buttressing effect increased the factor of safety by at least 11%. As a result, a loss of suction, coinciding with low river level, was found to be a significant destabilizing factor at the Ripley Landslide. Research contributions from the study improved our understanding of the interrelated factors driving landslide displacement rates and are generally applicable to other landslides in the Thompson River valley. Impacted railway operators may use the knowledge presented in this thesis to identify hazardous conditions leading to increased maintenance and landslide risk throughout the Thompson River Valley rail corridor.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| 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".