Horonobe Underground Research Laboratory Project Plan of the Investigation Program for the 2004 Fiscal Year (2004/2005)

Hama, Katsuhiro ; Amemiya, Keiji; Yamaguchi, Takehiro

The Horonobe Underground Research Laboratory Project is planned to extend over 20 years. Investigations will be conducted in three phases, namely from the surface (Phase 1), during construction of the underground facility (Phase 2) and in the underground facility itself (Phase 3). The 2004 fiscal year is the fifth year of the Phase 1 surface-based investigations.Geophysical, geological, surface hydrogeological and borehole investigations are being carried out in order to develop techniques for exploring the geological environment. Geoscientific models are being constructed, revised and verified based on the acquired data. As part of the development of techniques for monitoring the geological environment, long-term monitoring of groundwater pressures is ongoing in a borehole equipped in a previous investigation phase. Long-term monitoring systems are also being installed in the remaining boreholes at the site and measurements are ongoing. Development of a remotely operated monitoring system (ACROSS) is also continuing. Studies on the long-term stability of the geological environment include monitoring with seismographs, GPS and electromagnetic surveys. With a view to developing engineering techniques for application in the deep underground environment, a basic design for the underground facility has been defined. To provide input for the detailed planning of the Phase 2 and 3 investigations, laboratory tests are being carried out on the transportation and emplacement of the engineered barriers and on tunnel reinforcement materials. With a view to improving their reliability, the appropriateness of safety assessment methods is being examined using field and laboratory data. The design of the surface facilities has been defined and construction work has begun. Environmental monitoring is ongoing, as is collaboration with domestic and overseas research institutes.