DEM Exploration of Stress Transmission and Small Strain Behavior of Rubber Sand Mixtures

This paper presents a method to create rubber clumps without significant volume loss within the framework of the discrete-element method (DEM), enhancing the understanding of particle-scale stress transmission and small strain behavior of sand-rubber mixtures. Extensive calibrations were conducted, including the compressive response of individual pure rubber clumps, the small strain stiffness and the shear behavior of pure rubber specimens. These calibrations aimed to accurately capture the key characteristics of rubber materials, including their deformability. The calibrated model was then used to study the mechanics of sand-rubber mixtures. The simulation data indicated a higher coordination number for rubber clumps, a result of their greater deformability and significant sensitivity to stress levels in comparison with sand grains. The research has further demonstrated that the proportion of the overall stress transferred by the rubber remained below its volumetric content, highlighting its significant sensitivity to stress and density levels, which are characteristics not significant in sand particles. Additionally, the small strain stiffness values of sand-rubber mixtures decrease with increasing rubber contents, reflecting the negligible contributions of rubber materials on small-strain stiffness. This observation supports the validity of refined state variables that exclude rubber materials when characterizing the small-strain behavior of sand-rubber mixtures. While this research is fundamental, the data presented herein can be useful to engineers working on embedding waste materials such as granular rubber in engineered fill.