Experimental study of effect of gradation on compaction properties of rockfill materials

Gradation has a great effect on rockfill's compaction characteristics. If quantitatively descripting the effect of gradation on rockfill's compaction can be realized, the optimal gradation can be found. Firstly, a gradation equation is introduced to quantitatively describe gradation curve. Then a series of maximum dry density tests on rockfills with different gradations were carried out. The paper finds that the maximum dry density shows a logarithmic relationship with the maximum particle size and a parabolic curve relationship with the gradation area. Based on this, a model is developed to describe the influence of gradation on rockfill's compaction quantitatively. In the model, the optimal gradation curve area can be obtained according to the maximum particle size. The method to determine the optimal gradation curve according to the optimal gradation curve area is then proposed. Consequently, the optimal gradation distribution of rockfill in the field can be obtained based on findings of the paper.