Measurement of dynamic properties of rubber-sand mixtures across wide strain amplitudes by combined resonant column and cyclic simple shear tests

Abstract

The systematic exploration of the dynamic characteristics of various rubber-sand mixtures (RSM) across a wide range of strain amplitudes (10⁻⁶∼10⁻¹) addresses a pivotal challenge in the deployment of recycled waste tires as an economical, energy-absorbing material in geotechnical earthquake engineering. This study aims to elucidate the dynamic characteristics of this distinctive soil under wide strains and explores the appropriate particle size selection, optimal ratio, and initial state parameters for RSM as a geotechnical seismic isolation system. The investigation initiates with a series of resonant column tests to determine the dynamic shear modulus and damping ratio of RSM at small strain amplitudes, considering different rubber contents (RC), particle size ratios (PSR), and confining pressures. Subsequently, cyclic simple shear tests with larger strain amplitudes were conducted to examine the dynamic properties of RSM across a wide range of shear strains. The results indicate that: The PSR of rubber to sand significantly influences the dynamic parameters of RSM at small strains, resulting in a 3–4 fold change in the maximum dynamic shear modulus, which is attenuated at large strains, and exhibiting a coupling effect between the PSR and RC on the dynamic shear modulus and damping ratio. Over a wide strain amplitude range, including rubber particles enhances the damping characteristics of sandy soil. At small strains, the damping ratio gradually increases with the rise in RC; however, under large strain conditions, the variation trend of the damping ratio depends on the specific RC. when the RC increases from 0 % to 25 %, the dynamic shear modulus of RSM decreases significantly. As the RC further increases to 30 %, the extent of reduction in the dynamic shear modulus decreases significantly. These findings on the dynamic behavior of RSM under different strain conditions are crucial for guiding future theoretical research and engineering applications in seismic protection.