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Tsusaka, Kimikazu; Koizumi, Yu*; Tanimoto, Chikaosa*; Kameyama, Katsuhiro*; Miyajima, Yasuyuki*
Tonneru Kogaku Hokokushu (CD-ROM), 18, p.77 - 84, 2008/11
In TBM tunneling, secondary fragmentation is considered as a phenomenon that rock pieces between a cutter head and face are fragmented through the excavation process. The fragmentation should cause damage and excessive wear to the disc cutters which pass through the dome-shaped part where scrapers scoop up muck. Based on the cutter replacement records in four TBM applications through sedimentary and granitic rocks, the authors investigated the difference in the rolling distance per unit disc diameter loss between the inner cutters and the outer ones. As a result, it was clarified that the cutter life at the outer part were shorter than that at the inner part by more than 20% by the secondary fragmentation.
Hara, Masato; Kinoshita, Harunobu; Ikeda, Koki; Yamamoto, Masaru; Nobuto, Jun*
Tonneru Kogaku Hokokushu (CD-ROM), 18, p.23 - 30, 2008/11
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.
