Abstract: Studying the development characteristics of cracks in expansive soil under the effect of dry-wet cycles is crucial for understanding the deformation and failure mechanism of expansive soil channel slopes. Addressing the current research limitations, an experiment on expansive soil crack development focusing solely on dry-wet cycles is conducted. Utilizing the block discrete element method based on the crack development pattern in expansive soil, a deformation analysis of expansive soil channel slopes is performed through programming. The study yields the following findings: (1) Water evaporation in expansive soil undergoes a transition from initial evaporation to stable evaporation, followed by deceleration rate evaporation and residual evaporation phases. (2) As the number of wet and dry cycles increases, the area ratio of expansive soil cracks gradually increases and then tends to stabilize. The total length of cracks increases progressively, while the average width of cracks continuously decreases and gradually stabilizes, and the angle between cracks transitions from T-shaped to Y-shaped. (3) The distribution of soil particles always develops towards a stable direction, the stress distribution between particles develops towards a more advantageous state, and the distribution of expansion and contraction cracks gradually stabilizes. (4) Applying the block discrete element method to analyze expansive soil slopes has successfully integrated the displacement and stress fields, taking into account cracks and hygroscopic expansion. (5) The wet-dry cycle effect accelerates crack development, with higher crack rates resulting in increased slope deformation, expansion of the plastic zone, and significant deformation at the base of expansive soil slopes.

Key words: expansive soil, dry-wet cycle, expansion and contraction cracks, channel slope deformation