UBC Theses and Dissertations
Compilation and critical assessment of observations from a selection of historical tailings dam breach events for numerical breach and runout modelling Adria, Daniel Alexander Mackenzie
Tailings Dam Breach Analyses and various modelling software are used to estimate consequences of a hypothetical failure at a Tailings Storage Facility. The results of such forward-analyses are used in risk assessments and emergency planning. Many model inputs and approaches are currently based on expert judgment or adapted from other fields. There is some existing research and guidance for modelling approaches applicable for Tailings Dam Breach Analyses, however, there are few resources available that assess the hydrotechnical and geotechnical characteristics for dam breach and runout modelling from multiple diverse events. This presents a challenge for the experts who must make specific judgements for forward-analysis with little available hindsight into previous events. To address this knowledge gap, detailed investigations into 12 historical tailings dam breach events across a range of Tailings Storage Facility arrangements and taxonomies were completed. The investigations considered the outflow volumes, breach characteristics, and observations of downstream impacts. Some of these values or observations were previously reported by others for some events, but never previously compiled for the specific purpose of breach and runout modelling. These previous reports were critically assessed and included where relevant. Several original interpretations were made, and novel data were uncovered for many of the events evaluated in this thesis. Misconceptions regarding the events were frequently encountered, which likely contribute to the existing dearth of hindsight. Using the compiled information, a back-analysis model was developed to simultaneously simulate the breach and the tailings runout for the 12 events using HEC-RAS. HEC-RAS is a publicly available software for water resources and geohazards modelling. The modelling used the parametric breach method and non-Newtonian flow capabilities within HEC-RAS. The non-Newtonian flow parameters were determined through a comprehensive calibration process. The quality of the terrain data and misconceptions were found to be the most influential on model fit to any observed impact. The investigations and 12 models form the most comprehensive, diverse, and detailed tailings dam breach database to date. The insights from the investigations and modelling are applicable to forward-analysis Tailings Dam Breach Analyses, and the database serves as a springboard for multiple avenues of future research.
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