Abstract: It is necessary to study the strength of a single particle since its individual strength might govern the shear strength of the soil or rock mass. The uniaxial compression tests on the individual grain with three different average particle sizes was performed on three different average calcareous sand particle sizes using a house made single particle strength testing device to evaluate the relationship between the vertical load and the correspondent displacement. An optical microscope was used to obtain single particle contour images and an image processing software was used to extract shape parameters. Particle shape parameters were used to evaluate the particle breakage forms under different particle shapes. Three types of breakage models corresponding to the particle shape parameters were derived. The Weibull distribution theory was used to calculate the particle strength. The average particle sizes are 1.79 mm, 3.63 mm, and 8.15 mm. The corresponding characteristic stress of the particles are 11.23 MPa, 7.31 MPa and 4.62 MPa, respectively. The characteristic strength of the particles decreases with increasing particle size with a strong size effect demonstrated.

Key words: Calcareous Sands, Individual Particle Strength, Characteristic Stress, Particle Shapes