Mizunami Underground Research Laboratory Project; Rock mechanical investigations in situ stress measurements and laboratory tests using core on the GL.-200m level of research galley

Hirano, Toru; Seno, Yasuhiro*; Matsui, Hiroya 

Japan Atomic Energy Agency is proceeding with the geoscientific research at the Mizunami Underground Research Laboratory. In this project, developing a conceptual model of the geological environment is one of the scientific and technical objectives. Once excavation of research galleries began, the model could be improved using more detailed information from underground-based investigations. The investigation described here in is the measurement of the rock mechanical properties and initial stress of the rock mass around the GL.-200m level research gallery. The average physical and mechanical properties determined using core from the Toki Granite on this level is consistent with the properties from MIZ-1 testing. In situ stress measurements indicate that the 1 is 10.6 MPa and horizontal in the NW-SE direction matched to the observations in MIZ-1 at the same depth. This indicates that the surface based investigations in MIZ-1 are valid at this level.