Soil desiccation cracking triggered by surface defects: Insight and mechanism based on strain/displacement analysis using DIC

Soil desiccation cracking is a prevalent natural phenomenon that poses significant geotechnical and geoenvironmental challenges. Cracks typically initiate at surface defects such as air bubbles, large aggregates, tiny pits, or uneven surfaces, where localized stress concentrations are readily induced. This study conducted a series of laboratory desiccation tests on slurry samples to investigate the initiation and propagation of desiccation cracks in the presence of varying types and quantities of surface defects. Digital image correlation (DIC) technology was employed to monitor the strain and displacement fields on the soil surface during the desiccation process. The results reveal that strain and displacement data derived from DIC can precisely predict the initiation sites and propagation directions of desiccation cracks. In samples with internal defects, cracks predominantly propagate through the defect, whereas external defects tend to initiate cracks along their edges. In samples with multiple defects, Y-shaped crack patterns generally form initially, followed by T-shaped and straight cracks, driven by the evolving stress field. The dynamic interplay between crack formation and tensile stress redistribution governs the initiation and propagation of desiccation cracks.