Acoustic Emissions Monitoring of Cohesive and Cohesionless Soils during Consolidation and Shear Phases

This study investigates acoustic emissions (AE) in cohesive and cohesionless soils during consolidation and shear phases under triaxial loading. Ottawa sand and EPK clay specimens were tested under drained and undrained conditions, respectively, using an AE-enabled triaxial system. AE signals were recorded using sensors embedded in the loading caps. Results show distinct differences in AE activity and intensity between soil types. During consolidation, sand produced more emissions early due to rapid drainage, whereas clay showed a delayed AE response concentrated near the end of primary consolidation. During the shear phase, sand exhibited significantly higher AE activity and intensity compared to clay, aligning closely with the stress–strain curve. In contrast, clay exhibited high AE activity at early strains due to cohesion mobilization, followed by an increase in intensity at larger strains as frictional resistance developed. These findings demonstrate that AE can capture the internal structural evolution of soils and offer promise for monitoring critical transitions in both granular and cohesive materials.