Correlation between liquefaction resistance and shear wave velocity of sand-gravel mixtures: An experimental investigation

Case histories from more than 30 earthquakes worldwide have shown that liquefaction can occur in gravelly soils (both in natural deposits and manmade reclamations), resulting in large ground deformation and severe damage to civil infrastructure. However, evaluating the liquefaction potential and cyclic strain accumulation characteristics of gravelly soils remains a major challenge in geotechnical earthquake engineering. In this study, to provide new insights into this important topic, a series of stress-controlled undrained cyclic triaxial tests were performed, along with bender element shear wave velocity ( V S ) measurements, on reconstituted specimens of sand-gravel mixtures (SGM) with varying gravel contents ( G C ) and relative densities ( D r ). The experimental results indicated that both G C and D r have significant effects on the cyclic resistance ratio ( CRR ) and V S of SGMs, and both parameters should be considered jointly when evaluating the cyclic response, as similar macroscopic behavior can result from different combinations of density state and particle-size composition. Laboratory-based G C -specific CRR - V S correlations were also developed and found to be consistent with existing V S -based liquefaction triggering relationships derived from gravelly soil case histories. • The cyclic resistance and shear-wave velocity of sand–gravel mixtures both increase with increasing gravel content and relative density; however, these effects are interdependent and should be evaluated together when assessing the mechanical behavior of the mixtures. • The VS1-based liquefaction-triggering curves for sand–gravel mixtures shift progressively to the right with increasing gravel content, transitioning from the clean-sand boundary proposed by Andrus and Stokoe [ 27 ] toward the gravel-specific curves recently developed by Zhou et al. (2022) and Rollins et al. (2022).