ABSTRACT
This chapter describes modelling of particle breakage and the formulations of new stress-strain relationships for monotonic and cyclic loadings. Since triaxial testing is considered to be one of the most versatile and useful laboratory methods for evaluating the fundamental strength and deformation properties of geomaterials, a triaxial specimen has been considered as the basis for formulating the relationship between stress, strain, and particle breakage. 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. The chapter presents a new constitutive model for ballast incorporating particle breakage for monotonic loading, where the shear stress is increased from an isotropic initial stress state (i.e. initial stress ratio is zero).
