POSIVA Report 2015-1



Geological and Geotechnical Mapping Procedures in use in the ONKALO


Norokallio, J.



Page count:



ISBN 978-951-652-243-5


This report describes and evaluates the geological and geotechnical mapping procedures used in the ONKALO underground rock characterization facility. The described procedures will also be applied in the repository tunnels.

At present, the geological mapping procedures used in ONKALO are divided into three different stages: round mapping, systematic mapping and supplementary studies. The main purpose of the round mapping stage is to obtain geological data for the geotechnical assessment of the rock mass for excavation purposes, especially for the design of tunnel reinforcement. At this stage, the round is also 3D-photographed. The round mapping is performed from below the shotcreted roof of the previous round. The systematic mapping takes place soon after the roof of the round has been shotcreted. Most of the geological data is gathered during this phase and after the mapping, all observations are measured with a tachymeter to obtain precise location data. The supplementary studies comprise several mapping phases, which include mapping of the significant fractures (Tunnel Crosscutting Fractures - TCF), detailed mapping and descriptions of deformation zone intersections, as well as petrological and mineralogical sampling. Many of these features are already recognized during the round and systematic mapping, but their detailed definition and description is completed during this last mapping phase.

Over time, several improvements have been made to the mapping procedures used in ONKALO. The current mapping methods give both detailed information and an extensive view of the geology of the excavated areas. However, the development of the mapping procedure is still undergoing as described at the end of this report.


ONKALO, geological mapping, mapping procedures, round mapping, systematic mapping, supplementary studies, evaluation.


Geological and Geotechnical Mapping Procedures in use in the ONKALO (pdf) (4.8 MB)


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