Evaluating the liquefaction potential of gravel soils with static experiments and steady state approaches

Liquefaction generally occurs in loose sandy soils, whereas static (i.e., post) liquefaction is reported to occasionally take place in gravel soils (i.e., gravel-sand mixtures). Recent studies imply specific in situ parameters such as relative density or effective stress correlate with the static liquefaction potential of gravel soils, although they are insufficient to quantitatively estimate the liquefaction potential of gravel soils. In this study, the mechanism and the phenomena of static (post) liquefaction in gravel soils have been studied in detail through laboratory experiments. A state parameter (ψ) has been adopted to evaluate the static liquefaction and stress variation behaviors of gravel soils for a steady state Condition. Undrained (CU) triaxial tests were performed on gravel soils with different initial densities and confinement levels. State parameters for specific gravel contents at various initial relative densities are obtained from experimental programs, and are correlated with the liquefaction resistance of gravel soils. The liquefaction potential of gravel soils is then analyzed in terms of external and internal factors. The results indicate that the state parameter is an effective indicator of static liquefaction of gravel soils.