Static Liquefaction Triggering and Post-Liquefaction Strengths of Coarse Oil Sand Tailings

Saturated oil sands tailings can be susceptible to static liquefaction if deposited loosely. The occurrence of static liquefaction can thus pose a major risk to an oil sands tailings dam. This study presents the results of a series of monotonic undrained and drained triaxial compression tests on moist-tamped specimens of coarse oil sands tailings. The experiments were conducted on specimens subjected to isotropic and laterally confined (K0) consolidation loads to assess the effect of stress anisotropy and initial shear stress on the liquefaction behavior of oil sands tailings. The triggering and post-liquefaction undrained strengths normalized by the major consolidation stress were observed to decrease with decreasing relative density or increasing void ratio. A significant effect of anisotropic consolidation was observed, causing higher liquefaction triggering strengths in K0-consolidated specimens than those mobilized in isotropically consolidated specimens. This was, however, diminished at large strains resulting in similar post-liquefaction undrained strength ratios.