To investigate the effect of seismic history on the liquefaction resistance of sand

two groups of centrifuge dynamic tests have been performed on models of saturated sand deposit. The response of excess pore pressure as well as deformation of soil column were monitored and recorded during testing. It was found that small earthquake could bring beneficial effect on the sand resistance to liquefaction by strengthening interlocking between particles and forming a more stable structures. On the other hand

re-liquefaction may occur on a once liquefied site when it is subjected to an earthquake with magnitude less than that causes the first liquefaction

due to the unstable structure formed in the re-sedimentation process. The experimental finding indicates the impact of seismic history on the liquefaction characteristics of sand

as well as the significance of study on microstructure of sand.