A novel approach for describing gradation curves of rockfill materials based on the mixture concept

Rockfill materials produced from weathering and blasting usually possess a spatial variability of particle size distribution (PSD). Thus, a large number of laboratory tests are required to determine the engineering properties of rockfill materials with various PSDs. To reduce the number of redundant tests, a novel approach based on the mixture concept is proposed to describe the grading curves within the PSD envelopes of rockfill materials. The constituents of rockfills with varying PSDs are divided into two parts, termed as the fine matrix and coarse aggregates according to a threshold distinguishing fine and coarse particles. Then, the original PSDs of rockfill materials are reproduced by assigning different coarse fractions. The applicability of the proposed method is evaluated based on Discrete Element Method (DEM). The mechanical behavior of the sample with fitted PSDs are found to be approximately consistent with the corresponding values of the original PSDs at the same relative density. This method can be adopted into classical elastoplastic models to predict the mechanical behavior of rockfill materials through only a few laboratory tests. The findings in this study provide an approach for evaluating the mechanical behavior of rockfill materials with numerous PSDs based on the mixture concept.