Considering that total rheological model is independent of stress path and rheological genetic characteristic of rockfill dam is omitted

a seven-parameter incremental rheological model which is more suitable for the rheological analysis of coarse grained material is achieved based on the theory of hereditary creep. The analysis of normal triaxial rheological test data of some rockfill indicates that: the linear function could be adopted to fit the relationship between ultimate volume rheological deformation and corresponding volume stress

and hyperbola function could be adopted to fit the relationship between ultimate shear rheological deformation and corresponding generalized shear stress; so rheological volume modulus and shear modulus of coarse grained materials could be calculated based on the above-mentioned functions. Finally

a verification analysis is done; it could be concluded that the incremental rheological model approximately agrees with the experimental results; and it can be applied to earth dam projects.