Permeability anisotropy induced by the shear displacement of rough fracture walls

[1] The permeability anisotropy that results from a shear displacement (U) over right arrow between the complementary self-affine walls of a rough fracture is investigated. Experiments in which a dyed fluid radially injected into a transparent fracture displaces a transparent one are presented. A clear anisotropy is observed in the presence of shear displacements and allows us to estimate the ratio of the permeabilities for flows parallel and perpendicular to (U) over right arrow. A simple model which accounts for the development of channels perpendicular to (U) over right arrow qualitatively explains these results and predicts a permeability decreasing ( increasing) linearly with the variance of the aperture field for flow parallel ( perpendicular) to the shear displacement. These predictions are then compared to the results of numerical simulations performed using a lattice Boltzmann technique and to the anisotropies measured in displacement experiments.