In high rockfill dam

particle breakage is one of the main factors that lead to dam deformation. However

because of the large size of the rockfill particles

the breakage degree of the prototype rockfill materials is difficult to be measured directly through laboratory test. Therefore

the common practice is to reduce the size of the prototype gradation particle to less than 60 mm before the laboratory test can be carried out. However

due to the significant difference between the prototype and the test gradation

the parameters measured in the test are often quite different from the actual parameters of the prototype rockfill materials

thus affecting the in-depth study of the mechanical properties of the prototype rockfill materials. In this paper

a new method is proposed to describe the change of particle size distribution (PSD). Firstly

based on the theory of Weibull distribution of the particle strength and fractal crushing of the particle

the calculation of PSD change of the original rockfill materials is elaborated. Then

the relevant parameters are obtained by conducting the single-particle crushing test

and by comparing with the triaxial test

the rationality of parameter selection is verified. Moreover

the effects of the discrete degree of particle strength on the shape of the PSD is analyzed. Finally

the relationship between the relative crushing parameters and stress state of the rockfill materials during loading is discussed.