The creep mechanism of rockfill is studied based on the creep test of large scale compression apparatus with breakage measurement .The main factor causing the creep deformation is theater the pores are fillde by the movement of smaller breakage rockfill under the effect for continuous compression deformation .The breakage of rockfill can be divided into two types
one is the breakdown under the main compression deformation deformation and the other is Anderson the creep strain .The breakage result in the change of rockfill gradation