The effects of fines content on the Young’s modulus of a sand

This Paper investigates the effect of fines on the degradation with strain of the Young’s Modulus of a sand. Increasing the fines content is found generally to decrease the axial strain at yield and accelerate post-yield stiffness degradation, in absolute terms. However, Young’s modulus-strain data for various sand-silt-clay mixes converged when normalised with reference to the maximum Young’s modulus E_max and a reference strain ref, to a simple hyperbolic expression. The variation in E_max with void ratio was estimated reasonably accurately using the adjusted Hardin and Black (1968, 1969) empirical expression, using the intergranular void ratio below and the global void ratio above the threshold fines content. This reflects the coarse-grain dominance of the structure at fines contents below the threshold, and the fine-grain dominance above.