Owing to the alternating processes of rainfall and evaporation, the compacted loess employed in ground and roadbed construction frequently experiences drying and wetting (D-W) cycles. These cycles are prone to induce substantial deformation of the soil mass, posing a risk to the integrity of buildings and infrastructure. Consequently, this study delved into the effects of D-W cycles on the deformation behavior of compacted loess, considering varying initial dry densities and water contents. To achieve a profound understanding of the deformation characteristics of the compacted loess, we meticulously monitored the resistivity ratio, crack ratio, and microstructure throughout the tests. Furthermore, a constitutive model was developed to forecast the deformation of compacted loess under D-W cycles. The findings revealed that both the vertical strain and crack ratio exhibited an upward trend with the increase in D-W cycle numbers, while they exhibited a downward trend as dry density increased. Notably, water content was identified as a significant factor affecting both the crack ratio and resistivity ratio. Additionally, the occurrence and progression of D-W cycles and cracks led to a slight increase in particle abundance and the proportion of total pore area. Meanwhile, during the wetting process, the infiltration of water softened the cementing substances, resulting in a disruption of the connections between aggregates. This made it much easier for cracks in the soil to expand after the sample dried. The constitutive model was meticulously constructed by incorporating yield surfaces that account for decreasing and increasing water contents. The validity of the proposed model was substantiated through a comparative analysis of the measured and calculated data. This comprehensive investigation furnishes a theoretical foundation for assessing the stability of compacted loess ground and roadbeds subjected to D-W cycles.

Compacted loess is widely used as road subgrade filling in northwestern China, but its stability is threatened by traffic loads and repeated dry–wet cycles, leading to subgrade settlement or collapse. This study investigated the compression and resistivity characteristics of Q₃ Malan loess under 0–3 dry–wet cycles by incremental loading (IL) and constant rate of strain (CRS) tests. A self-developed consolidation chamber was used for the IL and CRS tests with the simultaneous monitoring of deformation and resistivity, with the moisture content controlled within the range of 1% to 29% to 15%. The results showed that loess compressibility increased rapidly after the first dry–wet cycle and became slow after other dry–wet cycles; The primary compression index C_c and secondary compression index C_α rose as vertical stress increased, and C_α stabilized at a vertical stress larger than 200 kPa. Resistivity decreased with stress and cycles, and sharply decreased after the first cycle (enhanced pore connectivity) and stabilized after two to three cycles, matching the compression stages. The compression and resistivity characteristics obtained by IL and CRS tests had consistent variation rules, confirming the reliability of the tests. This study provides a preliminary laboratory theoretical basis for exploring the feasibility of using resistivity in subgrade deformation monitoring.