Effect of particle size and two-dimensional shape on internal friction angle of dry sand using image processing

Abstract

Shear behaviour is a fundamental soil property. In this study, sea sand from Ise Bay and Shirakawa Mikage sand was selected as the research material to establish a correlation between particle width, roundness, and internal friction angle. The average particle width, bulk density, free porosity, and roundness of the sand were measured. The internal friction angle of sand was measured using a direct shearing test. The sand shape is defined as roundness. The relationship between the particle width and the shape of the internal friction angle was analysed using multiple linear regression. The results showed that a strong linear relationship existed between particle width, shape, and internal friction angle. The roundness was negatively correlated with the internal friction angle, whereas the particle width was positively correlated with the internal friction angle. Within the studied sand particle width range, the effect of the roundness on the internal friction angle was much greater than that on the particle width. The R2 value indicated the suitability and effectiveness of the model. This study provides a new method for determining the internal friction angle.