Analysis on mechanical properties and evolution of mesostructure of soil–rock mixture samples from contact network perspective

Based on discrete element method (DEM), three kinds of soil–rock mixture (SRM) models with different coarse particle contents were established and triaxial compression tests were carried out. The results show that the force chains in the particle system playing the main bearing role need more lateral supports, which results in the contact with a higher coordination number and often bear larger contact force. The relationship between the contact’s carrying capacity and the coordination number can be fit by a quadric surface. Taking the fit quadric surface as the capacity function, the network-flow model of force transfer can be constructed to quantify the force transfer ability of a contact network. By connecting the maximum flow in the network with the hardening parameter of the unified hardening model, the stress–strain relationship of SRM can be predicted to some extent, which lays a basis for formulating micro–macro constitutive model for granular materials.