Saline soil

common in the western China

poses a significant threat to road engineering due to its salt swelling characteristics. Therefore

studying the water-salt migration patterns within saline soil subgrades and developing methods to interrupt this migration are crucial for road safety prevention and control. Based on the utilization of excavated waste soil

a new type of foamed lightweight soil based on saline soil is proposed as a subgrade separation fault in saline soil areas. Using self-developed equipment

we tested internal temperature changes

vertical displacements

and water and salt distribution after freeze-thaw cycles. The objective was to evaluate its salt insulation and swelling suppression capabilities and to explore the microstructure-based mechanisms underlying salt inhibition. Results indicate that under a temperature gradient

water and salt in the saline soil sample migrate upward

accumulating mainly in the middle and upper sections. Notably

the novel foamed lightweight soil separation fault effectively blocks water and salt migration

significantly suppressing salt swelling. Interestingly

a higher soil salt content results in a more pronounced anti-swelling effect. The porous structure of the foamed lightweight soil can not only store salt effectively

but also block salt migration

allowing salt crystallization within the soil

thereby reducing salt swelling damage.