Understanding the deterioration mechanism of Xiashu loess in dry-wet cycles

Abstract

The development of cracks and deterioration of mechanical properties in aeolian deposits are common phenomena during dry-wet cycles. The redistribution of soil particles and the change of clay mineral aggregates are some of the reasons for the change in soil properties in this process. In this paper, the physical and mechanical properties, apparent digital images, and scanning electron microscopy (SEM) were used jointly to analyze the properties of silty clays (Xiashu loess) during the dry-wet cycle. The amplitude design of the dry-wet cycle is 2.52%-28.39%, and the number of cycles was designed to be 2,4,6,8and 10 times. The results show that the shrinkage and breakage of clay minerals and the release of pore water stress are caused by the change in water content leading to the redistribution of aggregate particles. The permeability and swelling ability of soil tend to be stable, indicating the stable trend of particle redistribution. The soil cohesion and internal friction angle have an exponential relationship with the number of dry-wet cycles, and the exponential relationship parameters are related to the soil type. Based on the analysis of particle migration, it can better explain the reasons for the deterioration of soil mechanical properties.