Steady State Testing of Loose Sands: Limiting Minimum Density

The steady state line (SSL) of a soil is defined as the relationship between a soil's void ratio (or density) and its residual ``steady state'' or critical state strength. Recent testing of very low density sand samples indicates that the steady state line approaches a limiting maximum void ratio, representing a considerable departure from the assumption of a linear relationship between the logarithm of steady state strength and void ratio employed in many constitutive models. This recent testing suggests that a limiting minimum density exists, below which a sample will show no steady state shear strength at all. Moreover, this limiting density appears to occur at a relative density of $D_r=>$0%–10%. This technical note presents data regarding this apparent limiting density, based on the results of laboratory testing performed by four researchers on three different sands.