Abstract: Quantitative characterization of the roughness of rock mass structural surface has always been a focus in geotechnical engineering. In the light of previous characterization methods combined with scanning results of the three-dimensional topographic features of structural surface, we propose to characterize the first-order undulating structure by average undulation angle and average relative undulation amplitude, and the secondary fine rough structure by area expansion rate. We further established the correlation between the three-dimensional roughness coefficient of structural surface and the topographic parameters. Verification analysis demonstrate that the proposed method takes into account the influence of both the first-order undulating structure and the secondary fine rough structure. The calculated shear strength of structural surface is in good agreement with test value. The research finding is expected to provide reference for quantifying the roughness and estimating the shear strength of structural surface.

Key words: structural surface, hierarchical structure, topographic parameters, roughness coefficient, shear strength