Abstract: Gudehus-Bauer hypoplastic constitutive model and the determination of its parameters are studied in the paper. Confined compression test is used to determine the parameters hs and n of hypoplastic constitutive model for rockfill materials. According to the derivation of the model, the relationships between the parameters , and the confining pressure are established, and new fitting parameters are proposed. Considering the dilatancy for rockfill materials, a new term of volumetric strain is added into the linear term in the model with a good fit to the axial strain-volumetric stain curve of triaxial consolidated drained tests. The new parameters of the model and the improvement on Gudehus-Bauer hypoplastic constitutive model are verified by means of rockfill large-scale confined compression test and triaxial consolidated drained tests. Compared with the test results of rockfill materials, the present model and its parameters can simulate the stress-strain characteristics of rockfill materials, and can improve the simulated axial strain-volumetric stain curve. Finally, the simulation to the triaxial consolidated drained test in loading-unloading condition by the improved Gudehus-Bauer hypoplastic constitutive model is carried out, and the results show that the improved model has a certain application of unloading.

Key words: Gudehus-Bauer model, rockfill materials, hypoplasticity, confined compression, improved method of parameter