Effect of Plastic Fine Fraction on Dynamic Behavior of Clayey Sand

The dynamic behavior of clay-sand mixtures depends on their shear strain amplitude, confining pressure, fines content, initial relative density, mineralogy, plasticity index (PI), particle size distribution and shape. In this research, a series of dynamic triaxial tests were carried out to evaluate the effects of confining pressure and fines content on the dynamic parameters of clayey sand at medium-shear strain. For this purpose, various specimens with constant relative density and different contents of clay (0,10% and 20%) were prepared and tested under different confining pressures. It was found that, adding plastic fine content up to 20% results in the decrease of the dynamic shear modulus of clayey sand in comparison with that of pure sand. In addition, the effect of confining pressure on the raise of shear modulus of sand-clay mixture decreases by increasing fines content.