Determination of permeability in anisotropic rock-masses from integral samples

Abstract

A method is presented which makes it possible to characterize the permeability of a rock mass as an anisotropic magnitude - i. e. to determine its permeability tensor – from a characterization of its fracturing by means of integral samples.

For the purpose, a theory is developed by means of which the permeability tensor can becalculated   from the altitudes and openings of fractures and – if infillings are present - also from their coefficient of permeability. This theory is based on the assumption that the sampled fractures are continuous and plane, and have the same characteristics as the section of the fractures present in the samples Possible deviations with respect to this assumption are taken into account by means of correcting factors derived from the results of pressure tests in situ The permeability tensor of a rock mass at a point can be determined from a single integral sample, provided this is representative of the fracturing

Results of the application of the method are presented, which show it to look very promising