Numerical Study on the Mechanical Behavior of Sand-Rubber Mixtures under True Triaxial Tests

A series of numerical true triaxial compression tests were carried out on rubber-sand mixtures (RSMs) by means of the 3D discrete element method to study the effect of the intermediate principal stress ratio b on the failure properties of RSMs with different rubber contents (RCs), and to explore the effect mechanism from a microscopic point of view. The numerical simulation results show that as the intermediate principal stress ratio b increases and the peak deviator stress qpeak gradually increases, while the peak internal friction angle phi b first increases and then decreases. The numerical simulation results were compared with four common strength criteria, including the modified Lade-Duncan criterion, the SMP criterion, the FKZ criterion and the DP criterion. The comparative analysis showed that the existing common criteria cannot accurately predict the damage state of RSMs, suggesting the necessity for further research. At the micro level, the combined effects of the intermediate principal stress ratio b values and RC on the micro-parameters, such as the coordination number, average normal stress between particles, probability density and anisotropy, were investigated.