Dynamic Evolution of Desiccation Cracks and Their Relationship with the Hydraulic Properties of Expansive Soil

The desiccation cracking of expansive soil plays a crucial role in the structural integrity and long-term stability of infrastructure foundations. While the occurrence of surface cracks and shrinkage deformation in expansive soil has been widely acknowledged, limited research has been conducted on the development pattern of internal cracks and their correlation with hydraulic properties. In this study, undisturbed samples of expansive soil were subjected to high-precision X-ray computed tomography scanning, and three-dimensional visualization and quantitative characterization of the cracks within the samples were conducted using the Avizo (version 2022.1) software analysis platform. Additionally, seepage simulations were employed to study the relationship between crack structure and the hydraulic properties of expansive soil. The results indicate that the desiccation process led to a significant increase in the volume content and connectivity of cracks in the expansive soil. Based on their connecting states, the cracks were classified into interconnected and isolated categories. Regression analysis suggests that the degree of cracking in expansive soil is predominantly determined by the interconnected cracks. The initiation, propagation, and coalescence of desiccation cracks substantially augmented the number of flow paths and enhanced the hydraulic conductivity of the soil. This study elucidates the microscopic evolution of desiccation cracking in expansive soil, offering a better understanding of the relationship between the three-dimensional characteristics of crack structure and their hydraulic properties.