Roughness Evolution of Granite Flat Fracture Surfaces during Sliding Processes

Abstract

Roughness is an essential factor affecting the shear process of discontinuous surfaces, and the evolution of roughness is closely related to the mechanical behavior of discontinuous surfaces. In this paper, with the help of granite specimens, a direct shear test was carried out on flat fracture surfaces obtained by sawing in order to study the evolution of roughness with shear slip. During the tests, the roughness evolution was evaluated using the arithmetic mean, root mean square and power spectral density of the roughness. The variation in these parameters all indicate that the friction surface with large slip tends to be rougher, at least under the loading conditions in this paper. And the increase in normal force will enhance this process, while the loading rate seems to have little effect on the roughness evolution. Finally, the analysis of the power spectral density shows that the roughness evolution in the spatial frequency of the profile line is mainly reflected in the middle– and low–frequency part, while the high–frequency part corresponding to the microscopic roughness body does not change much throughout the shear process.

Keywords

• granite fracture surfaces
• shear slip
• roughness evolution
• power spectral density (PSD)