Effect of Mechanical Properties on the Angle of Repose of Clay Soil

The angle of repose (AoR) is a critical calibration parameter in characterizing soil mechanical properties. This study examines the AoR across seven levels of soil moisture content. The fixed funnel method was used to measure AoR, complemented by a newly developed image-processing algorithm for AoR calculation. This algorithm effectively captures the irregular and rugged edges due to moisture-induced soil aggregation. The results indicated a consistent, monotonic increase in AoR with increasing moisture content. A model incorporating soil cohesion and internal friction angle was established to explain the observed AoR trends. Results suggest that changes in AoR are primarily driven by soil cohesion, with a relatively smaller influence from internal friction angle especially in moist conditions.