A comparison of the normal stress and hydraulic conductivity coupling for fractures in the laboratory and in-situ

Paper in proceeding, 2010

The coupling between hydraulic conductivity and normal stress along a discrete fracture has been developed from laboratory tests on small-scale samples. Those results for crystalline rock show a strong coupling between flow and normal stress, particularly when the normal stress is less than approximately 10 MPa. The flow for 611 discrete fractures was determined at the Forsmark site over depths ranging from 100 to 800 m. The orientation of the these discrete fractures were determined using Bips images and the normal stress acting on the fracture calculated from the in-situ stress model for the site. The strong coupling between stress and flow observed in small-scale laboratory tests is not supported by the in situ results.