Cyclic loading tests were performed both experimentally and numerically to study the effect ofimpact loading velocity on the settlement of a shallow granular layer like a ballasted track. In the experimentequal-sized spherical balls were regularly stacked to make a granular layer to compare the result with 2D DiscreteElement simulation. It was found that residual settlement after cyclic loading increased with increasing loadingvelocity when we used the unfinished pinballs with rough surface. On the other hand, the experiment withpolished pinballs with smooth surface gave an opposite tendency. The results of DEM simulations imply that avolumetric increase due to the strong impact loading accelerates the deformation of the assemblage of unfinishedpinballs, while it leads to considerable reversal of displacement during the off-loading process in the polishedpinball assemblage.
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