Experimental study on the rheological behaviour of fine-grained soils with sand content and liquidity index (water content)

Abstract

Rheological properties such as yield stress and viscosity is the main parameters to determine the fluidity of the debris flow. In this study, to evaluate effects of sand content and liquidity index (water content) on the rheological properties of fine-grained soils, several series of laboratory tests were performed on specimens with various sand contents of 0, 5, 10, and 15 % or with various liquidity indices ranging from 5 to 12.3. The flow behavior was strongly influenced by liquidity index (water content) and sand content. The overall shape of the flow curves of specimens had characteristics of a shear thinning fluid, with a decrease in viscosity as shear rate increased. The yield stress and viscosity gradually decreased as the liquidity index increased. At a given liquidity index, yield stress and viscosity of soil increased with an increase in sand content. Also, the yield stress and viscosity tend to increase with increasing concentration by volume(Cv) of the fluid matrix. The values of the four coefficients α1, α2, β1, and β2 were obtained by regression analysis for each fine-grained soil.