The evolution law and parameters of the model based on finite characteristic ratio theory (FCRT) are determined through the triaxial tests for coarse

medium and fine sands; the stress-strain relation of triaxial tests and that of the model match well. It shows that the FCRT model can describe naturally an important physical phenomenon that the sand samples of different inner grain sizes

which outer size are same

are of the different response properties

such as the strain of the sample with bigger inner grains is greater while other conditions are same.