Effect of saturation on liquefaction potential and residual strength: laboratory investigation

International audienceIn the last few years, many studies have focused on the behaviour of unsaturated sands subjected to dynamic loading and there is consensus that soils with saturation degree lower than 100% can be liquefied. However, it is still necessary to have systematic studies for better understanding of this phenomenon. In this study, some experiments were carried out to survey the sand mechanical behaviour subjected to cyclic loading as well as the residual strength after liquefaction under monotonic loading. All the samples were prepared by the wet tamping method then the Skempton parameter B was measured to evaluate the saturation degree of the sample. After that, sample consolidation and cyclic loading were conducted step by step. All tests show that the soil liquefaction susceptibility goes up with the increase of the sample saturation degree. Through these tests, the relationship between cyclic stress ratio and Skempton’s parameter B is also highlighted. After liquefaction, the samples were loaded monotonically to assess the residual strength. The results show that the sand recuperates its strength when the pore water pressure dissipates after liquefaction