Effects of confining stress, density and initial static shear stress on the cyclic shear response of fine-grained unclassified tailings

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A constant-volume direct simple shear apparatus was used to investigate the effects of confining stress, initial static shear stress and void ratio on the liquefaction resistance of fine-grained tailings. The cyclic resistance ratio (also expressed as the overburden stress correction factor) was found to decrease with increasing confining stresses in the range 100–400 kPa and to gradually increase from 400 kPa onwards, when samples were tested at the same initial void ratio. The presence of an initial static shear stress decreased the liquefaction resistance. A key outcome of the work was to reveal the critical importance of density on liquefaction susceptibility of compressible tailings. Thus, a combined correction factor to account for overburden stress and density on cyclic resistance was proposed.