Grain crushing is a basic behavior of rockfills. It affects the strain and strength characteristics of rockfills significantly. For high rockfill dams
the rockfill grains will be crushed largely because of large confining pressure. The grain crushing may increase the deformation rate of rockfill dams. To understand the behavior and mechanism of rockfill dams
the behavoirs of rockfill grain crushing were researched. By use of large-size triaxial tests the quantity of rockfill grain crushing was studied. The influence factors such as density
gradation and rock strength were investigated. The relationship between grain crushing and stresses acted on the rockfills was studied. The model to calculate the quntity of grain crushing rate and the relations of strains caused by grain crushing with grain crushing rate were proposed.