Embedding a flow rule into the hypoplastic creep model of rockfill materials

A hyperbolic flow rule describing the relationship between the inclination of the strain path and the stress ratio during creep was proposed based on triaxial creep experiments on two different rockfill materials. The flow rule was then incorporated into Bauer´s hypoplastic model together with a new density factor which controls the magnitude of creep strain. The refined model was verified by reproducing the experimental observations obtained from conventional triaxial experiments and triaxial creep experiments under constant effective stress. Good agreement between the numerical results and the relevant experiments lend sufficient creditability to the effectiveness of the refined model and motivate its application in predicting the long term behaviour of rockfill structures such as rockfill dams and rockfill railways in the future.