In order to study the effects of gravel contents, confining pressures and stress level on creep properties and laws of clay mixed with gravel, drained triaxial creep tests under different confining pressures and stress level were carried out for clay-gravel mixtures with different mixture proportions. The gravel contents were 30%, 40%, 50% and 70%, respectively. The confining pressures were loaded from 50 to 200 kPa and the stress levels were varied from 0.21 to 1.04. Test results indicated that instantaneous and creep deformation would take place evidently for clay mixed with gravel after being loaded. The creep strain would prone to a stabilizing value finally. The creep strain of clay mixed with gravel decreases with the increase of gravel contents, and increases with the increase of confining pressures and stress level. An empirical creep function including three parameters was presented to describe the stress level-axial strain-time behavior of clay mixed with gravel. The axial strain-time and stress level-axial strain behavior can be denoted with hyperbolic functions. Meanings of parameters in this model were analyzed and the values of parameters for rockfill were determined.
