The rock volume and the available underground excavations are divided between the experiments performed in Äspö HRL. It is essential that the experiment sites are allocated so that interference between different experiments is minimised.
Allocation of Sites
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New Experiment Sites
In the project Expansion of Äspö HRL (Hard Rock Laboratory) 2011-2012, tunnels were excavated to provide new experiment sites for continued technology development in full scale under realistic conditions. The expansion of Äspö HRL was mainly carried out at -410 masl, but also at -450 masl. A total of 308 m of tunnels were excavated using drill and blast, consisting of three access tunnels and eight experiment tunnels.
All the tunnels were grouted with low-pH cement, except the tunnels TAS04, TAS05 and TAS06.
The geoscientific investigations included drilling of two pre-investigation boreholes; KA2051A01 and KA3007A01, and two pilot boreholes; KA3011A01 and KA3065A01, drilled inside the tunnel contour of the planned access tunnels.
All tunnels were geologically mapped concerning bedrock types and fracturing as well as deformation zones using the new SKB tunnel mapping system RoCS. The rock surface, walls and roof, were photographed using photogrammetry, hence the dimensions of the tunnel are available in digital form in 3D.
Geology and hydrogeology
The rock types in the excavated area are dominated by Äspö diorite with subordinate occurrence of Ävrögranodiorite and minor inclusions of fine-grained granite, gabbroid-dioritoid and diorite-gabbro. The rock types in the expansion area are very similar to the rock types in general at Äspö HRL.
Four deformation zones (DZ1 to DZ4) have been interpreted, modelled and observed. Twelve hydraulic conductive features (HCF) have been interpreted based on information from probe hole drilling, PFL (Posiva flow logging), hydraulic response-and interference tests during and after drilling. The transmissivity of the interpreted features are between 10-7 to 10-6 m2/s and between 10-6 to 10-5 m2/s.