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Static Liquefaction of Nearly Saturated Oil Sand Tailings

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

The susceptibility of saturated mine tailings to static liquefaction has detrimental implications to the stability of tailings dams often used to store mine waste tailings. However, a large volume of a tailings dam may not be saturated and the matric suction within the partially-saturated or unsaturated tailings would provide additional strength and safety against static liquefaction. The degree of saturation to reduce the risk of static liquefaction is nevertheless unknown and the possible saturation of the partially-saturated zones of a tailings dam might lead to a potential instability of the dam. This study presents undrained shearing behaviour of oil sand tailings at different saturation ratios (Sr). Specimens with different amounts of water contents were prepared by moist-tamping in a cylindrical mould and subjected to triaxial compression shearing following isotropic consolidation. Sr was determined based on the volume, mass, and water content of each specimen. Water content was further confirmed by the volume of water pumped into or out of the specimen during sample preparation and consolidation. An empirical relationship was found between Skempton’s pore pressure parameter (B) measured during the saturation procedure and Sr for the oil sand tailings of this study. Although saturated tailings exhibited strain-softening and complete liquefaction in undrained shear, nearly-saturated specimens (Sr = 98, 97%) became increasingly more resistant to static liquefaction with reducing Sr, and exhibited dilative behaviour with even a slight reduction in Sr. Further analysis of the experimental results suggested that the effect of reduced saturation on lowering the liquefaction potential was primarily associated with the higher compressibility of the pore fluid.

Text

2023-12-08

Attribution-NoDerivatives 4.0 International

http://hdl.handle.net/2429/86777

Unreviewed

http://creativecommons.org/licenses/by-nd/4.0/