Factors Influencing the Dynamic Shear Modulus and Damping Ratio of Granulated Rubber–Clay Mixtures in Xiong’an New Area

Abstract

In this study, the dynamic properties of a mixture of granulated rubber and locally sourced Xiong’an clay are investigated, to promote the beneficial use of rubber–clay mixture (RCM) as a seismic isolation material in this area. A series of cyclic triaxial tests in the shear strain range of 10^–4 ~ 10^–2 is conducted, considering various scenarios of granulated rubber content, effective confining pressure, water content, dry density, cycle number, and consolidation time. The influences of these factors on the dynamic shear modulus and damping ratio of RCM are investigated and dominant factors are revealed. The results show that the shear modulus of RCM decreases with increasing rubber and water content whereas an opposite trend appears for the increased confining pressure, dry density, and consolidation time. Rubber content appears to be a dominant factor for the normalized shear modulus. The damping ratio of RCM is significantly related to the rubber content and effective confining pressure. A shear strain threshold of about 0.3% is observed concerning the influence of rubber content on the damping ratio. The G/G_max ~ γ and D ~ γ curves of RCM can be well described by the Hardin–Drnevich model. Based on the test results, correlations of the parameters of the Hardin–Drnevich model with rubber content and effective confining pressure are developed. The proposed empirical formulas can provide a useful guide in the estimation of dynamic properties of RCM for the preliminary design calculations before detailed laboratory measurements have been performed in the study area.