Effect of electrolysis desaturation treatment on micro-structure of liquefiable silica sands

Electrolysis desaturation is an emerging ground improvement technique with significant potential for widespread application in liquefaction mitigation. This method reduces the saturation of foundation soils, thereby decreasing soil liquefaction potential during earthquake. To date, there is still a lack of systematic research on the microstructure evolution of silica sands during the electrolysis desaturation treatment. In this study, non-destructive low-field nuclear magnetic resonance (NMR) technology was employed to investigate the effects of electrolysis desaturation on the silica sands at the microscale. The results showed that the electrolysis desaturation treatment had negligible effects on the structures of micropores and mesopores. The macropores in fine sand expanded during electrolysis, and the increasing current amplified the extent of this expansion. Conversely, in coarse sand, the macropores contracted during electrolysis. Bubbles generated by high-current electrolysis tend to aggregate, causing cracks and surface uplift in the fine silica sand. For the coarse silica sand, the generated gas accumulates within the existing voids, resulting in an insignificant impact on the soil structure. The electrolysis desaturation treatment primarily facilitated the expulsion of free water in both fine and coarse silica sands. In fine silica sand, employing a high current can reduce saturation more effectively within the same duration, but it also allows for more gas bubbles to escape after resting. Coarse silica sand maintained a high desaturation efficiency due to its greater porosity. This study provides a rational explanation in microscale of the structural impacts of electrolysis desaturation treatment on foundation soils.