Energy-based assessment of cyclic liquefaction behavior of clean and silty sand under sustained initial stress conditions

In practical engineering, sand deposits containing some finer particles usually sustain an initial static shear stress. This study investigates the sustained initial stress effect on liquefaction response of saturated sand through conducting cyclic undrained triaxial tests. The obtained response of sand samples containing a small amount of silty fines is compared to that of clean sand under similar relative densities. The results exhibit that various stress conditions result in two response patterns named as cyclic mobility and residual deformation accumulation. It is shown that the addition of silty fines can either enhance or reduce the cyclic liquefaction resistance of sand, depending on the fines content, while the sustained initial stress plays a beneficial role in resisting cyclic failure for samples with or without the addition of fines under otherwise identical testing conditions. It is also found that the dissipated energy accumulated in both the silty and clean sand follows a power-law relationship to the generated residual pore pressure during cyclic loading. A unified relationship is further established between the liquefaction resistance and dissipated energy, which may be useful for developing an energy-based assessment of in-situ soils using strength data from laboratory experiments.