Mizunami Underground Research Project, Annual report in the 2002 fiscal year

Ota, Kunio ; Amano, Kenji  ; Kumazaki, Naoki; Matsuoka, Toshiyuki; Takeuchi, Shinji; Masumoto, Kazuhiko; Yabuuchi, Satoshi

The current geoscientific research of the Mizunami Underground Research Laboratory (MIU) Project have been carried out since the 1996 fiscal year at the Shobasama site in Akeyo-cho, Mizunami City, Gifu Prefecture. The main goals of the MIU Project are to establish appropriate methodologies for reliably investigating and assessing the deep subsurface, and to develop a range of engineering techniques for deep underground application in granite. The site for MIU construction was changed in January 2002, from the Shobasama site to city-owned land (MIU Construction Site) after lease contract with Mizunami city. The surface-based investigations at the MIU facility site have started since February 2002. In 2002 fiscal year, geophysical survey and shallow borehole investigations was conducted and deep borehole investigations have started for modeling and characterization of geological environment in the MIU Construction Site before sinking the shafts. Detail of study and survey during the construction phase of MIU project was planned based on the layout and plan of construction of the underground facilities for development of engineering technologies in a deep underground. In Shobasama site, VSP survey was carried out to improve the model of geological environment. Hydrogeological model was calibrated using the results of long-term pumping test and long-term subsurface and groundwater monitoring. Important factors for hydrogeological modeling were evaluated as the results of numerical analysis by multiple approaches of groundwater flow modeling. The preliminary analysis based on the rock mechanical model at the Shobasama site was performed to estimate the deformation caused by excavation of the underground facilities.