Quantitative characterization of the anisotropy of rock joint roughness is crucial for evaluating joint mechanical properties. However

the complex structure of joint surfaces and the limitations of current analytical methods pose significant challenges to roughness calculation and anisotropy evaluation. This study focuses on shale from the Pengshui area in Chongqing

China

combining fractal topography theory and the joint roughness coefficient (JRC) to characterize the anisotropy of joint surfaces. Using a 3D laser scanner

the morphology of joint surfaces from shale samples fractured in different directions was captured. JRC and Fractal Dimension (D) of joint profiles were then calculated in various directions to compare joint surface anisotropy. The results indicate that: (1) JRC

which considers both fractal properties and amplitude characteristics of joint profiles

shows a stronger correlation with fracture orientation than D. Using the bedding plane of shale as a reference

a larger angle between the reference plane and the fracturing direction results in a higher JRC value for the joint surface. (2) The JRC values for a single joint surface can be approximated by an elliptical fit

with the area of the ellipse increasing as the angle between the rock bedding and the fracturing direction increases. This implies that when the fracturing direction is perpendicular to the bedding plane

the fracture surface is rougher. This research provides a reference for characterizing joint surface anisotropy and offers guidance for understanding the relationship between fracturing direction and joint surface roughness.