Abstract: Noticeable uneven settlement is observed in high-fill embankments of station fields in mountainous regions of China in complex environmental conditions.A systematic study was executed on the water-retention characteristics of unsaturated coarse-grained soil under diverse scaling methods,as well as its strength and deformation characteristics under varying confining pressures,water contents,and strain rates.Notable disparities exist among the air intake values of the soil water retention curves obtained via the three scaling methods.The sample derived through the similar grading method possesses the highest air intake value,the most robust water retention capacity,and the largest volumetric deformation during the consolidation phase.There are substantial differences in the stress-strain and volumetric characteristics of unsaturated coarse-grained soils under different scaling methods,demonstrating a significant strain rate effect.With the increase of strain rate,the cohesion c value escalates and the internal friction angle φ value diminishes.Soil samples obtained through the mixed method and equivalent substitution method initially experience shear shrinkage followed by shear expansion,while those obtained via the similar gradation method consistently exhibit shear shrinkage.The soil sample derived from the mixing method displays a smaller cohesive force c value,a higher internal friction angle φ value,and a greater critical peak strain rate in comparison to the similar grading method.