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Recent publications

Workreport 2016-57



EDZ Study Area in ONK-TKU-3620: Determination of Seismic Wave Velocities at Six Load Levels, Petrophysical and Rock Mechanical Properties of Drill Core Specimens


Jacobsson, L., Kjell, G., Brander, L., Kiuru, R.



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Laboratory experiments on specimens from the excavation damaged zone area in the ONK-TKU-3620 were conducted. The experiments comprised density and porosity measurements, P- and S-wave velocity measurements at unloaded condition in one direction and at uniaxial compression in three orthogonal directions, indirect tensile tests and uniaxial compression tests on cylindrical specimens of veined gneiss (VGN) and granitic pegmatoid (PGR). All tests were conducted on saline (formation) water saturated specimens.

The density and porosity measurements revealed a dependence of the saturation procedure between the one used at the Finnish Geological Survey and the one recommended by ISRM. It should be noted that the applied procedure deviated slightly from the procedure defined by the ISRM. The deviation decreased after saturating the specimens again by long-term immersion in water (5 weeks or more) and re-measuring the specimens in water saturated state. Increased porosity compared to the other tested specimens could be observed in one specimen that had a visually observable sealed joint. Some other specimens had a slightly increased deviating porosity.

The wave velocities measured under loading in three directions showed anisotropy in almost all specimens. The anisotropy was expected in the structurally anisotropic VGN specimens. Anisotropy was also observed in the structurally isotropic PGR specimens. The anisotropy in this case may be either a weak foliation or oriented microfractures. The anisotropic wave velocity data match measured strains. The wave velocities for the VGN also match the response that is expected at transverse isotropy which is a suitable constitutive model assumption for the VGN.


EDZ, laboratory experiments, density, porosity, P-wave velocity, S-wave velocity, ultrasonics, Brazilian test, UCS test, acoustic emission


WR 2016-57_web (pdf) (58.9 MB)


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