Research on Dynamic Characteristics and Modulus Attenuation Evolution of Rubber Particle Loess

Loess in seasonally frozen regions is prone to water-induced softening and dynamic instability, posing severe challenges for geotechnical engineering. Rubber particles, as sustainable waste-tire-derived material, offer potential for loess improvement. This study aims to elucidate the dynamic characteristics and modulus attenuation evolution of rubber particle–loess mixtures under multi-factor coupling effects. Dynamic triaxial tests were conducted to investigate the influences of rubber content, particle size, moisture content, and freeze–thaw cycles. Results reveal that the optimal mix is 5% rubber content with 40-mesh rubber particles, which yields the highest dynamic strength (i.e., the maximum dynamic stress that can be sustained before failure). The dynamic constitutive relationship follows the Hardin–Drnevich hyperbolic model. Increased moisture content and more freeze–thaw cycles reduce the maximum dynamic elastic modulus and strain, while higher confining pressure enhances them. A dynamic elastic modulus attenuation model was established to characterize strain-softening behavior. These findings clarify the dynamic response mechanisms of modified loess, providing a theoretical basis for its engineering application in seasonally frozen regions.