Geometrical and transport properties of single fractures: influence of the roughness of the fracture walls

TL;DR

This review paper discusses how the roughness of fracture walls in geological materials affects their geometrical, mechanical, and transport properties, emphasizing the importance of surface roughness in flow and dispersion within fractures.

Contribution

It provides a comprehensive overview of the characterization of fracture surface roughness and its impact on void space geometry, mechanical behavior, and fluid transport properties.

Findings

Surface roughness significantly influences void space structure.

Failure mechanisms affect the correlation of free space.

Roughness impacts permeability and hydrodynamic dispersion.

Abstract

This article reviews the main features of the transport properties of single fractures. A particular attention paid to fractures in geological materials which often display a roughness covering a broad range of length scales. Because of the small distance separating the fracture walls, the surface roughness is a key parameter influencing the structure of the void space. Studies devoted to the characterization of the surface roughness are presented as well as works aimed at characterizing the void space geometry. The correlation of the free space is found to be crucially function of the failure mechanism (brittle, quasi brittle or plastic...) but also of possible shear displacements during the failure. The influence of the surface roughness on the mechanical behavior of fractures under a normal load and a shear stress is also described. Finally, experimental, numerical and theoretical works devoted to the study of the influence of the fracture void geometry on the permeability and on the hydrodynamic dispersion of a dissolved species are discussed.