Pre-excavation grouting in construction of Mizunami Underground Research Laboratory

Hara, Masato; Kinoshita, Harunobu; Ikeda, Koki; Yamamoto, Masaru; Nobuto, Jun*

In the excavation for the ventilation shaft of the Mizunami Underground Research Laboratory, pre-excavation grouting with ordinary Portland cement is conducted to reduce the water inflow. The target value for the hydraulic conductivity of grouted zone is set to be 2 Lugion, considering mainly the capacity of water treatment facility. In this paper, the grouting work conducted up to the depth of GL. -220m is summarized. By reviewing the water inflow and hardened cement injected into rock fractures observed at shaft wall, the validity of grouting method so far is evaluated.