Abstract: Acknowledging the significance of particle breakage in rockfill due to its large size and angularity, this study incorporates the particle breakage energy dissipation coefficient into the stress-dilatancy relationship of the Cambridge model. Triaxial test results on sand gravel and landslide dam materials validate this modification within the theoretical framework of the generalized plastic model. Key findings include: (1) The energy consumption coefficient of particle breakage exhibits a unimodal curve, initially increasing and then decreasing with shear strain during testing. (2) The modified stress-dilatancy relationship captures the non-linear characteristics of shear-dilation curves for both rockfill types. (3) The stress-strain curves of diverse materials align well with the stress-dilatancy relationship, incorporating particle breakage and the generalized plastic model, showcasing traits of strain hardening, shear compaction, and shear dilatancy.