Impact of the overall regularity and related granulometric characteristics on the critical state soil mechanics of natural sands: a state-of-the-art review

This research aims to establish accurate correlations between critical state characteristics and particle shape parameters in terms of overall regularity (O-R), considering the gradation and packing density aspects of natural sands. For this purpose, a database of physical and mechanical characteristics [sphericity 'S', aspect ratio 'AR', convexity 'C-x', overall regularity 'O-R', mean grain size 'D-50', critical state intercept 'e(Gamma)', critical state gradient 'lambda' and critical state friction angle 'phi(cs)'] related to 21 sands have been compiled from the existing literature. The evaluation and analysis of the collected data indicate that the overall regularity parameter is found to be a suitable factor for the prediction of the critical state parameters ('e(Gamma)', 'phi(cs)') compared to the critical state gradient 'lambda' of the compiled sands. Moreover, this study gains an insight on the prediction of the overall regularity through the packing density (e(max) and e(min)) and gradation (D-50 and C-u) of the compiled data to be estimated of physical characteristics of sandy soils. In addition, this research gives the intention to help scientists and researchers to use systematically the proposed expressions in their researches to explore the influence of the overall regularity parameter on the macro and micro-mechanical response of granular soils.