Abstract: The triaxial test data show that the stress ratio at the failure state of compacted rockfill and gravel significantly decreases with the increase of confining pressure, while their stress ratio at the critical state is substantially constant with high confining pressure. The expressions for the stress ratios at the failure state and the critical state are established according to the experimental data. For the existing generalized plasticity model which does not reasonably reflect the compressibility of soil-rockfill, a practical generalized plasticity constitutive model for soil aggregates is proposed considering complex loading conditions by adopting the improved dilatancy equation and using the indoor compression and triaxial test results. The calculated values are in good agreement with the experimental data by compiling programs for the above model to simulate the test load of earth-rockfill materials. The proposed model can reasonably reflect their stress and deformation characteristics.