Discrete element modelling of railway ballast

The discrete element method has been used to simulate the behaviour of railway ballast under different test conditions. Single particle crushing tests have been simulated using agglomerates of bonded balls, and the distribution of strengths correctly follows the Weibull distribution, and the size effect on average strength is also consistent with that measured in the laboratory. Realistic fast fracture can be obtained if non-viscous damping is reduced. Oedometer tests on aggregates of crushable ballast particles have also been simulated and compared with the results from laboratory tests. Finally, box tests which simulate traffic loading have been simulated using both spherical balls and 8-ball clumps. It is found that the 8-ball clumps give much more realistic behaviour due to particle interlocking.