Dynamic Behavior of Sand/Rubber Mixtures, Part II: Effect of Rubber Content on G/G O -γ-DT Curves and Volumetric Threshold Strain

This paper examines the strain-dependent dynamic properties (G/GO-logγ-DT curves) of dry and saturated sand–recycled rubber mixtures in a range of shearing strain amplitudes from (5 × 10−4) % to (6 × 10−1) % using a fixed-free torsional resonant column device. The effect of the rubber content on the pore water pressure buildup and volumetric threshold strain γtv of saturated mixtures, as well as the effect of specimens’ geometry on the experimental data, are also presented and discussed. Based on a comprehensive set of experimental results, a modified hyperbolic model, frequently used in practice, has been proposed. An increase in the rubber content leads to a more linear shape of the G/GO-logγ and DT-logγ curves and a reduction in the pore water pressure buildup. Damping is expressed in terms of DT-DTO, which eliminates the effect of the rubber content and the mean confining pressure. The final aim is to propose appropriate design G/GO-logγ-DT curves for sand–rubber mixtures currently used in practice.