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DESICCATON AND CONSOLIDATION MODELLINF OF OIL SANDS FINE TAILINGS DEPOSITS
Session: Mining Geotechnique IV / Géotechnique minière IV
Paul Simms, Carleton University (Canada)
Gholami Mahsa, Carleton University (Canada)
Oil sands tailings deposition is regulated by enforcing reduction of the volume of fluid fine tailings over the life of an operation. Fluid fine tailings are defined by a 5 kPa undrained shear strength value. Operators are meeting these targets by improving dewatering and consolidation characteristics of fine tailings through various techniques, often involving addition of polymer or other flocculation-inducing treatment. However, the assessment of the strength performance of these technologies is typically quantified using a field vane. This gives one or two numbers, peak and residual strength. Element testing, while challenging for mature fine tailings, does give a richer description of strength behaviour. We compare shear behaviour of samples consolidated and sheared in simple shear and in triaxial element tests, and compare these findings to available field data on in-line flocculated mature fine tailings. Both un-amended and amended tailings behave as a structured soil, showing very high shear strength to effective stress ratios. Shear strength values as a function of density show values comparable in trend but lower than shear strength measured by field vane at some field trials.
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