As a typical discontinuous medium, discrete granular materials’ creep behavior plays a crucial role in the formation and evolution of geological disasters such as landslides and debris flows. However, systematic research on the interaction mechanism between particle size and deviatoric stress and its impact on creep behavior remains insufficient. To reveal the coupled effects of particle size and deviatoric stress on creep behavior, this study conducted indoor creep tests on silica spherical particles under multiple conditions and systematically analyzed the influence patterns of different particle sizes and deviatoric stresses on the creep characteristics of granular materials. Based on the Derec creep model and experimental results, this study constructed a quantitative computational model of the creep state of granular materials and clarified the regulatory mechanism of particle size on the creep parameters of the system. The results indicate that the creep behavior of granular systems essentially reflects the dynamic balance between internal deformation and resistance to deformation within the particles. Creep parameters significantly influence system creep characteristics by regulating particle slip and creep behavior. Specifically, as particle size increases, the creep value of the system increases markedly, making it more prone to entering a liquid-like flow state. Concurrently, the system’s resistance to deformation declines while exhibiting heightened sensitivity to deviatoric stress. Furthermore, an increase in particle size not only significantly enhances the fluidity of the particle system but also amplifies its sensitivity to changes in deviatoric stress. Particles with larger diameters show a more pronounced response under high deviatoric stress conditions, and the flow characteristics of granular materials are more susceptible to particle size variations. This influence manifests as a positive correlation between particle size and both the system′s initial state parameters and characteristic strain, while exhibiting negative correlations with viscosity coefficient, critical creep velocity, and critical creep stress.

To reduce the environmental pollution caused by waste rubber tires, it is an effective solution to process them into derived aggregates and apply them in engineering reinforcement. Currently, geogrid reinforcement technology is widely used in embankment and slope projects. However, due to the limitation of soil resources, most of the local fine aggregates are used for backfill and compaction, which leads to the geogrid not being able to give full play to the reinforcing effect. Therefore, this paper proposed the method of composite reinforced embankment of waste tire rubber particles and geogrid to solve the above problems. The influence of rubber particle content (0%, 5%, 10%, 15%, and 20%) on the shear characteristics of the mixed soil was examined using a triaxial shear testing system. Additionally, pullout tests on geogrids were conducted to investigate the effects and mechanisms of rubber particle content on the pullout characteristics of uniaxial, biaxial, and triaxial geogrids. Finally, the deformation characteristics and stability of reinforced soil embankment with rubber granular soil mixture were analyzed by indoor tests and numerical simulation methods. The results indicate that the elastic modulus of the mixed soil gradually decreases as the rubber particle content increases. At the same time, the shear strength index shows an initial increase followed by a decrease, reaching its maximum value at a content of 15%. The peak tensile force of the three types of geogrids in the mixed soil follows the same trend with its maximum value at a content of 15%. The addition of 15% rubber particles in bi-axial and tri-axial geogrid-reinforced embankments reduces the settlement of the embankment by approximately 19% and 23%, respectively, as well as the lateral earth pressure by approximately 18% and 23%. The presence of the composite reinforcement layer significantly limits the development depth of the slope failure slip surface, thus enhances the embankment’s resistance to deformation.