Effect of Joint Geometry and Transmissivity on Jointed Rock Hydraulics

Abstract

The effect of joint geometry parameters (joint orientation, joint density, and joint size) and joint transmissivity on the hydraulic properties of jointed rock blocks was examined in two dimensions using joint networks with two joint sets through numerical experiments. The chance for equivalent continuum hydraulic behavior and the average block permeability of jointed rock were found to be very sensitive to the relative orientation of the joint sets in a joint network system. Although both the equivalent continuum behavior and the average block permeability seem to be little affected by the change of the standard deviation of the joint orientation distribution, the degree of permeability anisotropy seems to depend on the standard deviation of the joint orientation especially for anisotropic joint systems. Chance for the equivalent continuum behavior and the average block permeability were found to increase with the increase of joint density and joint size. The chance for equivalent continuum behavior and the permeability anisotropy were found to depend on the distribution of joint hydraulic conductivity. The influence of the joint hydraulic conductivity is more prominent for joint systems with high joint density and large joint sizes. The greater the variation of the hydraulic conductivity value among the joints in a joint set, the lesser the chance for the medium to behave like an equivalent continuum porous medium.