Hydromechanical characterization of fractures close to a tunnel opening: A case study
Paper in proceeding, 2012

Important factors influencing the hydromechanical behavior of a fracture are in situ rock stresses (natural and induced) as well as hydraulic heads, fracture orientation, connectivity and fracture geometry, including their infillings. Particular attention is given to larger, water-conducting fractures that intersect or are close to a tunnel. For the Bentonite Rock Interaction Experiment (BRIE) at the Äspö Hard Rock Laboratory (HRL) in Sweden, the interaction between rock and bentonite in a deposition borehole is of particular interest. The BRIE experiment is being conducted at a depth of 420 meters in crystalline rock. This paper presents results from the initial identification, characterization and modeling of a small number of fractures close to the tunnel opening. So far, these fractures have been identified as the most important water-conducting fractures. In this identification and characterization exercise, core-drilled, vertical, three-meter deep investigation boreholes were made in the tunnel floor. Logging of natural hydraulic heads in boreholes and hydraulic tests, along with borehole and tunnel mapping in combination with modeling, indicate small deformations. This was also confirmed by deformation measurements performed in the boreholes. The description of the site will be further updated and revised and additional investigations into the link between stress history, fracture geometry and selection of fracture mechanical properties will be of particular interest.

Tunnel opening





Åsa Fransson

Chalmers, Civil and Environmental Engineering, GeoEngineering

Johan Thörn

Chalmers, Civil and Environmental Engineering, GeoEngineering

Lars O Ericsson

Chalmers, Civil and Environmental Engineering, GeoEngineering

Margareta Lönnqvist

Clay Technology AB

Chalmers, Civil and Environmental Engineering, GeoEngineering

M. Stigsson

Swedish Nuclear Fuel and Waste Management Company

ISRM International Symposium - EUROCK 2012

ISRM International Symposium - EUROCK 2012
Stockholm, Sweden,

Subject Categories

Geophysical Engineering

Civil Engineering

Geotechnical Engineering

Areas of Advance

Building Futures (2010-2018)

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