Size effect of anisotropic rock joint with two-order roughness

Abstract

AbstractThe primary objective of this work is to improve the understanding of the characteristics of the joint anisotropy in two-order morphology and its variations in size. In this respect, the wavelet analysis method is applied to isolate waviness from unevenness in three lithological natural joints. The 3D parameter $$\theta_{\max }^{ * } /(C + 1)$$ θ max ∗ / ( C + 1 ) is utilized to characterize the roughness of the two-order morphology in 36 directions, while the anisotropy behavior is quantified based on the anisotropic variation coefficient (AVC). The anisotropic distribution of two-order roughness in large-sized joint surfaces indicates that the first-order roughness mainly reflects the anisotropy of the total roughness, while the second-order roughness is mainly isotropic. Further analysis of the size effect of AVC values and the stable sizes of slate, tuff and limestone are determined to be 200 mm, 700 mm and 500 mm, respectively. Furthermore, the contribution rate of the two-order roughness to the total roughness is estimated in 36 directions based on the functional relationship between them, while the size effect of the contribution rate is utilized to explore the influence mechanism of the two-order roughness with size. These results provide a theoretical basis for exploring the size effect mechanism of the anisotropy of shear strength in two-order morphology.