Physical and Mechanical Properties of Sand-Gravel Mixtures Evaluated from DEM Simulation and Laboratory Triaxial Test

In railway tracks, ballast fouling due to fine materials mixing has been identified as a challenging issue. In this research, deformation characteristics of sand-gravel mixtures, simulating fine-ballast mixtures, were studied using laboratory and DEM-simulated triaxial compression tests. The DEM simulations were done in Yade, an open source developed based on DEM. Initially, void ratio characteristics of sand-gravel mixtures were studied. Then, triaxial compression tests were conducted for the specimens of 50% and 80% of relative densities. The void ratio results indicated that, initially, void ratios decreased with %sands. After reaching the minimum void ratios, void ratios increased with %sands. The triaxial test results indicated that, on average, similar behaviour in stress-strain curves, where, at initial %sands, stress-strain curves became higher and then, stress-strain curves became smaller, though it was slightly different in laboratory tests.