Quantifying the effects of freeze–thaw cycles on soil erosion resistance in the Loess Plateau, China

Freeze–thaw cycles (FTC) influence soil erodibility ($K_r$) by altering soil properties. In seasonally frozen regions, the coupling mechanisms between FTC and water erosion obscure the roles of FTC in determining soil erosion resistance. This study combined FTC simulation with water erosion tests to investigate the erosion response mechanisms and key drivers for loess with varying textures. The FTC significantly changed the mechanical and physicochemical characteristics of five loess types (P < 0.05), especially reducing shear strength, cohesion, and internal friction angle, with sandy loam exhibiting more severe deterioration than silt loam. Physicochemical indices showed weaker sensitivity to FTC versus mechanical properties, with coefficients of variation below 5 %. Wuzhong sandy loess retained the highest $K_r$ post-FTC, exceeding that of the others by 1.04∼2.25 times, highlighting the dominant role of texture (21.37 % contribution). Under different initial soil moisture contents (SMC), $K_r$ increased initially and then stabilized with successive FTC, with a threshold effect of FTC on $K_r$ at approximately 10 FTC. Under FTC, the $K_r$ variation rate showed a concave trend with SMC, turning point at 12 % SMC, indicating that SMC regulates freeze–thaw damage. Critical shear stress exhibited an inverse response to FTC compared to $K_r$, displaying lower sensitivity. The established $K_r$ prediction model achieved high accuracy ($R^2$ = 0.87, $\mathrm{NSE}$ = 0.86), though further validation is required beyond the design conditions. Future research should integrate laboratory and field experiments to expand model applicability. This study lays a theoretical foundation for research on soil erosion dynamics in freeze–thaw-affected areas.