Effect of Plasticity Index on the Spatiotemporal Evolution of Desiccation-Induced Strain Localization in Compacted Clayey Soils Using DIC

Clayey soils are often used for the construction of compacted geotechnical structures such as earthen dams, low-permeability barriers, landfill liners, etc. However, the formation of desiccation-induced cracks significantly reduces their mechanical strength and increases the risk of structural failure. Therefore, understanding the desiccation-driven strain localization phenomenon is essential for assessing the long-term stability of these structures. The current study investigates the influence of plasticity index on the spatiotemporal evolution of strain localization during drying. Bench-scale desiccation tests were conducted on compacted clay-sand mixtures with varying plasticity. Surface deformations were captured using Digital Image Correlation (DIC), and Green-Lagrangian strain maps were used to track strain evolution patterns. Results revealed a clear shift in strain localization tendency from the initial, boundary-driven low-strain zones to delayed, internally concentrated high-strain zones as the soil plasticity increased. These trends can be attributed to plasticity-driven microstructural transitions that influence drying dynamics and the corresponding strain localization.