Sand liquefaction is one of the most complicated and destructive earthquake hazards and the liquefaction behavior of sand has been investigated by many scholars,but the research results are inconsistent. In this study, a shaking table experiment was proposed to investigate the liquefaction behavior and mechanism of Guangzhou fluvial silty sand under repeated loading. Macroscopic liquefaction characteristics, including excess pore pressure buildup, cumulative settlement, were systematically recorded during cyclic loading events. Subsequently, optical microscopy was employed to capture meso-scale images of sand particles before and after each liquefaction cycle. A sand micro-image acquisition and analysis framework was established to quantify the evolution of particle arrangement(long-axis) and local void ratio before and after each liquefaction event. The experimental results indicate that under repeated loading, the sand can undergo multiple liquefaction events, and the occurrence of re-liquefaction is closely related to its density. Specifically, the liquefaction resistance of the sand decreases after the initial liquefaction event. This reduction in re-liquefaction resistance is attributed to the non-uniform distribution of particle arrangement and density induced by the first liquefaction.

Sand liquefaction, Shaking table tests, Macro-and-micro analysis