Abstract: Due to the large size of rockfill, it must be scaled by a certain percentage so that it can be used to carry out laboratorial triaxial test. However, the particle shape of rockfill may be different before and after scaling. Therefore, it is important to evaluate the effect of particle shape on the deformation behavior of rockfill material. In this study, a high-precision 3D laser scanning technology was introduced to analyze the spatial shape of the rockfill particles with the sizes of 2.5-5 mm, 5-10 mm, 10-20 mm and 20-40 mm of Zipingpu concrete face rockfill dam. Further, triaxial tests were carried out to determine the correlation between particle shape index and particle breakage. The results show that there exists an approximate semi-logarithmic linear relationship between the particle breakage and the particle sphericity for Zipingpu rockfill. With the increase of confining pressure, the effect of particle shape on particle breakage decreases and the effect of particle strength on particle breakage increases. The particle strength of Zipingpu rockfill gradually decreases with the increase of the particle size, but the particle breakage decreases with the increase of the particle size, which may be due to that the particle shape of Zipingpu rockfill become more and more irregular with the decrease of particle size. Therefore, the impact of the particle shape on the particle breakage should be paid enough attention before and after scaling.

Key words: rockfill materials, particle shape, 3D laser scanning technology, shape index, particle breakage