Research on Normal Deformation and Hydraulic Characteristics of Rough Fractures with Self-affine Topography

In fractured rock masses, fractures play a critical role in controlling fluid flow, where their surface morphology and deformation characteristics directly influence permeability. To investigate this relationship, we generated numerical fracture surfaces using a self-affine geometric model, combining two fracture topographies to establish initial flow space and permeability. Micro-asperities on the composite fracture surfaces were identified and analyzed, with their mechanical behavior during deformation modeled using Hertzian elastic contact theory. A progressive normal loading process was applied to simulate fracture closure, tracking the evolution of contact area, normal displacement, and stiffness parameters. Flow rates at selected stress levels were computed using the local cubic law, from which permeability and hydraulic aperture (dh) were derived. Through numerical modeling of multiple fracture realizations, we established a modified cubic law and a linear relationship between fracture closure and aperture reduction. The proposed empirical equation effectively describes aperture evolution and flow behavior in rough fractures during closure. By simulating fracture mechanics and flow space variation based on asperity deformation, this study provides a novel approach for coupled stress-flow analysis in rough fractured rock masses.