Detailed amount of particle breakage in nonuniformly graded sands under one-dimensional compression

Abstract

The coexistence of broken and unbroken grains in each size range can disturb the assessment of actual amount of particle breakage. In this study, a series of one-dimensional compression tests were carried out on three kinds of coral sands and a silica sand to clarify the detailed amount of particle breakage for nonuniformly graded sands. Before the compression tests, both coral and silica sand assemblies were divided into different grain-size groups and dyed in different colors, then mixed as nonuniformly graded packings. After the compression, grains of different color in each size range were discerned quantitatively by implementing particle images segmentation on images of grains. Results show that the extent of particle breakage was found to be larger than the change in relative mass percentage in most size ranges, and the new “absolute particle breakage” wd for each size range satisfied linear relationships with the logarithmic value of compression pressure. Compared with silica sand, coral sand has weaker abrasion under high pressure due to the strong interlock among grains. New breakage indexes of sand samples, based on detailed particle breakage, are proposed. The detailed particle breakage could be useful for proposing a breakage-dependent constitutive model of crushable granular soils.