ABSTRACT
Researchers and practitioners have long recognised that the ballast bed accumulates plastic deformation under cyclic loading. In case of railway ballast, the progressive change in particle geometry due to internal attrition, grinding, splitting and crushing, that is degradation, under cyclic traffic loads further complicates the stress–strain relationship. There is a lack of constitutive model, which includes the effect of particle breakage during shearing. A new stress–strain and particle breakage model has been developed, first for monotonic loading, and then extended for the more complex cyclic loading. To develop a constitutive stress–strain and particle breakage model in a generalised stress space, a three-dimensional Cartesian coordinate system was used to define the stress and strains in ballast. Since ballast is a free draining granular medium, all the stresses used in the current model are considered to be effective.
