Water Retention Curve (WRC) measurement methods and challenges of hard rock mine and oil sands tailings: Application to soil cover and multilayer deposition

Farzad Daliri, Sam Proskin, Trempess Moore

In the proceedings of: GeoOttawa 2017: 70th Canadian Geotechnical Conference; 12th joint with IAH-CNC

Session: Mining - Oil Sands I

ABSTRACT: The Water Retention Curve (WRC) or Soil-Water Characteristic Curve (SWCC) is an influential factor that should be estimated or measured to evaluate geotechnical engineering behaviour, such as unsaturated hydraulic conductivity and compressibility of sub-aerially deposited unsaturated tailings. WRC plays a key role in the design of covers with capillary barrier effects (CCBE) by estimating unsaturated hydraulic conductivity of materials used in the cover. Measuring WRC is also essential to estimate the optimum drying time in sub-aerially multi-layer deposition of tailings. Since tailings are not natural soils, there are challenges and complexities in measuring WRC of mine or oil sands tailings compared to the natural soils. This paper summarizes the application of WRC to tailings treatment technologies, reviews different methods to estimate or measure WRC of tailings, provides some results of WRC measurements of hard rock mine and oil sands tailings and discusses specific challenges in measuring WRC of tailings such as air entry value (AEV) measurement. WRCs were measured and compared in different variations of gravimetric-water content, degree of saturation, matric suction and total suction. Modified pressure plate device and a dewpoint hygrometer were used to measure matric and total suction respectively. The results of the measured WRCs were correlated with the shrinkage curve of the specimens. At the end, the paper provides some examples of the usage of the WRC in CCBE designs.

RÉSUMÉ: comportement géotechnique, tel que la conductivité hydraulique insaturée et la compressibilité de résidus insaturés déposés partiellement par voie subaérienne. La CRE joue un rôle clé dans la conception de couvertures à effets de barrière capillaire (CEBC) en estimant la conductivité hydraulique insaturée des matériaux utilisés dans la couverture. La mesure couches de résidus de façon subaérienne. Puisque les résidus ne sont pas des sols naturels, plusieurs défis se posent de la CRE à des technologies de traitement des résidus, se penche sur différentes méthodes pour estimer ou mesurer la CRE de résidus, fournit quelques résultats de mesures de la CRE de résidus de stériles miniers et de sables bitumineux ont été mesurées et comparées avec différentes variations de la teneur en eau gravimétrique, le degré de saturation, la succion matriciel.

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