Test execution of liquid-type grout at depth of 300m of Mizunami Underground Research Laboratory

Nobuto, Jun*; Tsuji, Masakuni*; Kusano, Takashi*; Mikake, Shinichiro ; Kamiya, Akira; Ishii, Yoji

At Mizunami Underground Research Laboratory, the water inflow should be minimized, considering water treatment expense. Although cement grout has been applied to reduce water inflow up to 460 m depth, water inflow through small fractures which cement grout cannot penetrate can not be neglected at deeper underground. Liquid-type grout which has high durability as well as good penetrability was therefore tested at the depth of 300 m. Test results indicated that liquid-type grout could sufficiently reduce hydraulic conductivity of rock mass with less than 1Lu, and could keep improvement effect even after applied water pressure of more than 9 MPa was applied.