On the influence of the spatial distribution of fine content in the hydraulic conductivity of sand-clay mixtures

Abstract

Sand-clay mixtures are one of the most usual types of soils in geotechnical engineering. These soils present a hydraulic conductivity which highly depends on the fine content. In this work, it will be shown, that not only the mean fine content of a soil sample affects its hydraulic conductivity, but also its spatial distribution within the sample. For this purpose, a set of hydraulic conductivity tests with remolded samples of sand-clay mixtures have been conducted to adjust a regression for the hydraulic conductivity depending on the fine content. Then, a finite element (FE) model simulating a large scaled hydraulic conductivity test is constructed. In this FE-model, the heterogeneity of the fine content is simulated following a Gaussian distribution. The equivalent hydraulic conductivity resulting of the whole FE-model is then computed and the influence of the spatial distribution of the fine content is evaluated. Variations of the mean fine content and the standard deviation have been considered to analyze the behavior of the equivalent hydraulic conductivity. The results indicate that the equivalent hydraulic conductivity is not only related to the mean fine content, but also on its heterogeneity. At the end, a simulation example of a water flow around a sheet pile, showed also that the flow rate depends on the fine content heterogeneity in a similar fashion.