# Effects of Freeze-thaw Cycles on the Mechanical Properties and Microstructure of a Dispersed Soil
## 1 Introduction  
Dispersed soil, consisting of fine-grained soil with a low salt content, exhibits rapid dispersion in water [1, 2]. Its low erosion resistance poses significant challenges in practical engineering. For instance, the slopes and foundations of excavated channels are susceptible to noticeable collapse under the influence of rainfall. The resulting soil loss threatens nearby engineering facilities and leads to substantial economic losses. In the seasonal freezing zone of western Jilin Province, dispersed soil is distributed widely [3]. Shallow soil or soil exposed to the surrounding environment in this region inevitably undergoes freeze-thaw cycles. Throughout the freeze-thaw cycles, water, ice, and water vapor in dispersed soil undergo transformations and continuous exchanges of matter and energy with the extrinsic environment, leading to changes in the soil structure [4]. Moreover, compared to other soil types, dispersed soil's soluble salts are more prone to crystallization and dissolution during freeze-thaw cycles, resulting in more complex structural changes and engineering geological properties [5]. Consequently, dispersed soil's physical and mechanical properties are altered [6, 7, 8], significantly reducing its physical properties and strength parameters [9]. These alterations directly influence the stability of foundations and superstructures constructed on scattered soil [10]. A comprehensive investigation of the mechanical properties and dispersion properties of dispersed soil in western Jilin Province is of vital practical significance precisely due to these issues. Researchers worldwide have extensively studied dispersed soil in seasonally frozen regions, focusing primarily on water-salt migration, freeze-thaw deformation, and physical-mechanical properties. [PERSON] et al. [11] conducted experiments in Hungary to comprehensively investigate the physical and chemical properties, as well as the composition, of dispersed soil. [PERSON] et al. examined the engineering geological attributes of dispersed soil in western Jilin Province, China. They explored the relationship between salinity, microstructure, and soil dispersion [2]. [PERSON] et al. [12] discovered the mechanical strength parameters of dispersed soil depend mainly on cementation and inter-particle connections. [PERSON] [13] investigated the impact of salt content, temperature, and unfrozen water content on the mechanical properties of dispersed soil under unconfined conditions, and the results revealed that soil particles, frozen water, and salt solution within the soil determine the strength of dispersed soil. [PERSON] [14], [PERSON] [15], and other scholars explored the creep and strength characteristics of dispersed soil under freezing conditions using experimental methods. In the study by [PERSON] [16], experiments were carried out to examine the material composition, deformation behavior, and strength of dispersed soil in seasonally frozen regions and establish the correlation between the strength of dispersed soil and temperature. [PERSON] [17] demonstrated a direct link between the shear strength of dispersed soil and the rate of applied strain. However, significant variations in soil properties arise from diverse geographical locations. As a result, investigations into the mechanical strength and microstructure of dispersed soil within the seasonal freezing region of western Jilin Province have encountered certain limitations. Changes in pore content and particle size distribution significantly impact the macroscopic soil characteristics and mechanical behaviors [18]. Utilizing laser particle size analyzers and scanning electron microscopes (SEMs) has become essential for observing particle size distribution and structural changes in soil, offering a valuable understanding of the impact of freeze-thaw cycles on the soil microstructure [19; 20; 21].