Pre-excavation grouting design, results and evaluation of a gallery at great depth in Mizunami Underground Research Laboratory

Tsuji, Masakuni*; Kobayashi, Shinji*; Sato, Toshinori  ; Mikake, Shinichiro 

Pre-excavation grouting of shafts and galleries has been conducted during the construction of Mizunami Underground research laboratory in the aspect of safe works and reducing the discharge treatment of the water inflow. The grouting methodology has been simultaneously studied an developed as there is less experience of grouting in low conductive rock with high water pressure, especially in Japan. Ahead of excavating GL.-500m gallery on the ventilation shaft side, grouting design was performed based on the estimation of water inflow by the pilot-boring investigations and the design was properly revised during the campaign. The gallery satisfied the inflow requirement with good sealing effect.