Effect of particle shape on density and permeability of sands

Particle shape is widely considered to be one of the most important factors affecting the behaviour of granular soils. This effect may change, based on variations in the grain size distribution. Therefore the effect of particle shape on the behaviour of granular soils should be investigated in soils of similar gradations. In this study, 20 different sands of five origins are initially subjected to image analyses in order to obtain data concerning shape characteristics. Then Proctor tests at three energy levels are conducted to obtain the densification characteristics of these soils. Basic statistical analyses are employed to obtain the distributions that the particle shape characteristics best fit. Empirical equations are developed to estimate the relative density of sands. Constant-head permeability tests are performed to determine the most suitable empirical formula for estimating the coefficient of permeability for granular soils. A new method for obtaining the shape coefficient for the Kozeny–Carman equation is proposed. Overall, relationships between a number of particle shape and fractal dimension parameters, as well as several statistics related to the relative density and permeability of soils, are investigated within an experimental framework.