A bounding surface plasticity model is presented for crushable rockfills in the framework of the critical state soil mechanics which includes translation of the critical state line due to particle crushing. A translating limiting isotropic compression line is also introduced and incorporated in the model to describe the position and evolution of the bounding surface. A particle breakage index is introduced as a function of stress invariants which controls the translation of the critical state and limiting isotropic compression lines. The performance of the model is demonstrated using the results of experimental tests on different types of rockfill materials conducted under both monotonic and cyclic loading conditions. The study shows the capability of the model in capturing the characteristic features of the behavior of rockfill and other crushable materials such as ballast and coarse gravel under both conventional and complex loading paths.