Effects of Excavation Damage on the Physical Properties of Rock Matrix

R. Kiuru*, L. Jacobsson, D. Király, J. Suikkanen

*Corresponding author for this work

Research output: Contribution to journalConference articleScientificpeer-review

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Abstract

Posiva Oy has conducted investigations into excavation damage, including comprehensive laboratory testing of physical properties of rock specimens from excavation damaged rock mass. Laboratory testing was conducted on drill core specimens extracted from the excavated surface of a tunnel located at approximately 345 m depth in Olkiluoto, Finland. A total of 141 drill core specimens of three main rock types, a structurally isotropic coarse-grained pegmatoid (PGR) and structurally anisotropic veined gneiss (VGN) and diatexitic gneiss (DGN), were subjected to petrophysical testing, rock mechanics testing and petrographic analyses. Results from the various tests were subjected to rigorous statistical analysis in order to reveal the effects excavation damage has on the physical properties of the rock mass. Results of the study revealed changes that are credited to excavation damage in resistivity, S-wave velocity and various elastic properties of the rock specimens. Effects of excavation damage and the depth of the excavation damaged zone seem to be different to gneiss compared to pegmatoid. On microscopic level, the extent of excavation damaged zone appears to be 0.2 - 0.4 m depending on the measured property. This means that the deeper excavation damaged layer observed by geophysical surveys may be caused by larger scale fractures.

Original languageEnglish
Article number012020
Number of pages7
JournalIOP Conference Series: Earth and Environmental Science
Volume833
Issue number1
DOIs
Publication statusPublished - 6 Sep 2021
MoE publication typeA4 Article in a conference publication
EventConference on Rock Mechanics and Rock Engineering, from Theory to Practice - Virtual, Online, Turin, Italy
Duration: 20 Sep 202125 Sep 2021

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