Effects of Wetting-Drying Cycles on the Strength and Microscopic Characteristics of Ili Loess

To investigate the strength degradation and microstructure characteristics of Ili loess under wetting-drying cycles, soil water characteristic curve measurement, triaxial shear test, and scanning electron microscope testing were used to study the changes in water holding characteristics of Ili loess, the effects of different dry densities, dry wet cycling amplitudes and times on the shear strength of Ili loess, and the changes in microstructure of Ili loess before and after dry wet cycling under different dry densities. The results show that the water holding capacity of Ili loess gradually decreases with the increase of wetting-drying cycles; The cohesion of Ili loess increases with the increase of dry density under the same number of wetting-drying cycles, and the trend of cohesion with the increase of dry density is consistent under different number of wetting-drying cycles. However, the relationship between internal friction angle and dry density and number of wetting-drying cycles is not obvious, indicating that wetting-drying cycles have little effect on the relationship between dry density and internal friction angle. In addition, after the wetting-drying cycles, the content of large and medium particles and pores in loess decreases, while the content of small particles and pores increases. Low dry density loess develops towards embedded compaction, while high dry density loess develops towards aerial arrangement.