Tire rubber material has the advantages of low density, strong linear elastic deformation ability, good durability and high energy consumption. The mixture of tire rubber derivatives and soil is widely used in geotechnical engineering and traffic engineering. In order to study the dynamic parameter characteristics of granular rubber-sand mixtures (which is a new type of subgrade filler) under cyclic train loading, the indoor consolidated undrained dynamic triaxial test was carried out. The effect of granular rubber content, confining pressure and loading frequency on shear modulus and damping ratio characteristics of the granular rubber-sand mixtures were studied. The research results showed that when the shear strain is constant, the shear modulus decreased with the increase of granular rubber content, increased with the increase of confining pressure and decreased with the increase of loading frequency. Based on the well-known hyperbolic law used by Hardin and Drnevichin, the shear modulus test results were fitted to obtain the maximum shear modulus, and the maximum shear modulus decreased with the increase of granular rubber content. When the shear strain is constant, the damping ratio of the granular rubber-sand mixtures increased with the increase of granular rubber content, and decreased with the increase of confining pressure. Based on the experimental results, the relationship between damping ratio and shear strain was established. In addition, based on the microstructure characteristics of flexible rubber particles and rigid sand particles, the influence mechanism of granular rubber on shear modulus and damping ratio of the mixtures was analyzed. According to the comprehensive research results, it can be concluded that the highest granular rubber content in the new subgrade filler is 20%. When the granular rubber content is not greater than 20%, the shear modulus of the new subgrade filler can meet the requirements and the damping ratio is relatively large, and it has a good damping and energy dissipation effect.
