The micro-mechanical behaviour of sand–rubber mixtures under shear: A numerical study based on X-ray micro-tomography

A CT image-based discrete element model (DEM) incorporating the realistic particle morphology of sand grains was developed to investigate the micro-mechanical behaviours of sand–rubber mixtures (SRMs) under triaxial compression. The model was validated by comparing the numerically simulated macro- and microscale mechanical behaviour of SRMs with the experimental results acquired in triaxial testing with in-situ μCT scanning. SRMs with irregularly shaped grains have a higher degree of heterogeneous distribution of contact force chains than those with spherical grains. Moreover, rubber content and particle shape have a significant influence on the ‘most active phase’, namely, the time-period during which the maximum number of contacts emerged to participate in the stress-transmission, of different types of contacts. The ‘most active phase’ of sand–sand contacts appeared earlier than that of sand–rubber contacts. SRMs with a lower rubber content were more likely to have an earlier ‘most active phase’ for each type of contact. The sequence of the ‘most active phase’ for the sand–rubber contacts and rubber–rubber contacts appeared during shear was affected by the particle shape of the SRM specimens. The results highlight the important role of rubber content and particle shape in the stress-transmission behaviour of SRMs. © 2023 Elsevier Ltd.