DEM simulation of the size effect on the wetting deformation of rockfill materials based on single-particle crushing tests

Abstract

Abstract Rockfill materials undergo additional deformation when immersed in water under constant-stress conditions. This phenomenon caused by flooding is called wetting deformation. Researchers have investigated wetting deformation via many factors through laboratory tests on scaled materials. However, the size effect on wetting deformation has seldom been studied due to the limited size of test equipment. To investigate this topic, a set of single-particle crushing tests was conducted on Gushui rockfill materials under wet and dry conditions, and triaxial wetting tests of samples with different grain sizes under constant confining pressure and stress ratio conditions were simulated by discrete element method (DEM). The single-particle crushing tests showed that wetting significantly reduced particle strength and stiffness and that particle strength decreased with increasing particle size. The stress-strain curves obtained by the DEM simulations were in good agreement with the experimental results. The wetting deformation of the large-sized sample was larger than that of the small-sized sample, especially under a high stress ratio and confining pressure. The wetting volumetric and axial strains had a linear relationship during flooding, and their ratio was greatly affected by the stress ratio. The size effect on wetting behavior should not be ignored, especially for high-rockfill dams.