The permeability variables of granular matter

Abstract

No “unique” relation between soil parameters and grading curves of granular matter can be elaborated. In case some statistics are used (e.g., d10), then infinite many grading curves may be related to the same value of it. Moreover, several densities can be related to the same grading curve, and different permeability values are measured at different densities. A model discrimination study was started to be made to suggest a saturated water permeability k – grading curve – density relation using some new measurements. The following model variables were tested: (i) various grading curve statistics, (ii) combined variables of harmonic mean diameter and density like specific surface are or hydraulic radius, (iii) density parameters like void ratio or the newly applied relative density. Two newly measured data sets were used with identical soil composition and different density (in more dense and less dense states). Both data sets consisted of 3 series of optimal 2-fraction granular soils, the fractions were: 0.25 to 0.5 mm, 0.5 to 1 mm, 1 to 2 mm and 2 to 4 mm. Each series consisted of 5 mixtures with the same, fixed relative base entropy A values (i.e., mean log d values). In addition, some earlier data sets were used to test the extension of the relations. According to the results, the regression for the new data was acceptable if extra density parameters were applied with either the (i) or the (ii) type parameters. The addition of earlier data bases increased the regression coefficient R2.