An Investigation of the Micro-Mechanical Contact Behaviour of Railway Ballast Particles

Abstract The micromechanical behaviour of basalt ballast particles was studied by subjecting them to normal (N) and tangential loading (T) under various loads. It is observed that the natural ballast particle pairs subjected to normal loading have a softer response than that predicted by Hertz (1882) theory. The coefficient of interparticle friction (μ), measured during monotonic shearing, is about 0.5-0.6, while during cyclic loading, μ was found to stabilise around 0.65-0.85 after about 30 cycles. The value of μ was not affected by the normal load or the loading rate. Roughness, measured before and after testing, was found to change with loading, attributed to deformation of the asperities.