LAUSR

Abstract Based on laser scanning technique and discrete element program, the fine mesoscopic model of irregular ballast particles was simulated well by series of bonded disc clusters, then the large-scale static and cyclic loading tests were used to determine the parameters of the discrete element model. On this basis, the plastic deformation and shakedown behaviors of ballast samples under cyclic loading were studied, and the effects of cyclic loading amplitude, confining pressure and loading frequency were discussed. The results show that, in plastic shakedown state, broken ballast particles were rare and the strain rate of the sample decreased rapidly with the increase of the number of load cycles; in plastic creep state, ballast particles were broken at the beginning of cyclic loading and then appeared stable deformation; in incremental collapse state, ballast particles were broken in initial cyclic loading, but the plastic deformation of the sample was mainly due to the rapid shear failure. The stress limits of ballast samples for different shakedown states increased with raising the confining pressure, but the influence of the loading frequency on the stress limits related to the stress levels of confining pressure, and accordingly, the empirical exponential models of the relationships between the stress limits (i.e. maximum principal stress) and the ratios of corresponding maximum principal stress to minimum principal stress were established.