Effect of size and strain rate on particle strength and stress–strain properties of rockfill materials

Abstract

The stress-strain properties of the rockfill materials under cyclic loading conditions are critical for the seismic safety analysis of dams. However, due to the effect of size and strain rate, the parameters obtained from the scaled laboratory tests may not accurately calculate the earthquake response. In the presented study, a novel approach has been developed to infer the prototype parameters based on the single particle strength. Firstly, a series of particle crushing tests with different sizes and loading rates were conducted. The results show that as the strain rate increases, the particle strength enhances and the size effect on particle strength gradually weakens. According to the established particle strength model, it is assumed that two specimens have homothetic particle size distributions and the same compaction, and is geometrically similar, then the size effect relations on macroscopic stress and strain tensors can be derived, a set of monotonic and cyclic triaxial tests are used to validate the approach. Furthermore, the effect of particle size and strain rate on the equivalent linear model is determined, the small-strain modulus parameter K obtained from the laboratory test should be modified. This study provides a reference to the engineering design and seismic safety evaluation of high rockfill dams.