Proposal of efficient pre-excavation grouting concept for deep underground rock excavation

Nobuto, Jun*; Mikake, Shinichiro ; Nishigaki, Makoto*

This paper describes a study on efficient pre-excavation grouting concept using cement grout for reducing water-inflow during excavation of crystalline rock in deep underground. Although thick grout mix is favorable for the efficiency of pre-excavation grouting, clogging phenomenon at the entrance of rock fractures in grout hole is concerned for thick grout mix. The influence of water-cement ratio on basic grout characteristics and clogging phenomenon is studied by laboratory experiment using cement grout with water-cement ratio of from 0.5 to 10.0. Finally, the efficient pre-excavation concept for the excavation of deep underground is proposed.