Shear Strength Properties of Thin Three‐dimensional Polyhedral Granular Interface

The shear strength properties of a thin three‐dimensional railway ballast layer were studied by mean of numerical vertical compression tests. Fresh and recycled ballast digitized grains were used. Vertical strength comes from the increase of face‐face contacts, which are more important in fresh ballast. Shape and force anisotropies are equally important for the layer strength in this thin confined configuration. Mohr‐Coulomb model was used to obtain the layer stiffness, which evolves with thickness variation and ballast type. A stiffness law depending of the layer’s thickness has been proposed from tests results, which could lead to a better understanding of stiffness influence on track irregularities.