PARTICLE BREAKAGE OF VOLCANIC ASH COARSE-GRAINED SOIL UNDER MONOTONIC AND CYCLIC SHEAR

Abstract

 In this study, element tests comprising monotonic and cyclic shear tests were conducted on volcanic ash coarse-grained soil, which is susceptible to particle breakage under external forces, to identify the stages during shearing at which particle breakage occurs. The soil samples were prepared with a particle size range of 2.00–0.85 mm to facilitate the quantification of particle breakage during shearing. The results from the monotonic shear test indicated that particle breakage did not occur at the point of maximum shear stress but was initiated when the effective stress path reached the failure line (FL). In the cyclic shear tests, pronounced particle breakage was observed under cyclic mobility conditions, where the effective stress path repeatedly approached zero effective stress and then recovered along the failure line (FL). These findings revealed that, in both shear test methods, particle breakage occurred after the effective stress path intersected the failure line (FL).