Effects of gradation on the mobilized friction angle for the instability and steady states of sand-silt mixtures: experimental evidence

This paper deals with a laboratory study of the influence of low-plastic-fines content and grading characteristics on the instability and steady-state friction angle of sand-silt mixtures under monotonic loading conditions. For this purpose, a series of compression undrained triaxial tests were carried out on Chlef sand (Algeria) mixed with low plastic fines (Ip=5%) ranging from Fc=0% to Fc=30%. The samples were prepared in the laboratory with the dry-funnel-pluviation method and subjected to three different confining pressures (Pc’=100 kPa, 200 kPa and 300 kPa). The obtained results indicate that the fines content, void ratio and gradation have a significant influence on the mobilized friction angle for the instability and steady state of the sand-silt mixtures and confirm the existence of simple correlations between the mobilized instability Wiebke Baille Bochum Ruhr University, Laboratory of Foundation Engineering, Soil and Rock Mechanics Bochum, Germany Mostefa Belkhatir University of Chlef, Laboratory of Material Sciences & Environment Algeria