ABSTRACT
In Japan, Ginza line first operated in 1927 was all constructed by cut and fill method. Compared, subway No. 12 which are under construction, most stations will be constructed by cut and fill method. The shield machines of Earth Pressure Balanced type shield machine which was developed in 1970s have been re-exported to Europe to construct the Dover Channel Tunnel and Lyon Road Tunnel. Main use of the shield machine is exapanding from small sewage to huge road tunnel. When excavating a long tunnel, method to replace cutter bits must be carefully studied. Shield technology and tunneling technology has reached a stage, with suitable ground pre-investigation, suitable machine to bore a tunnel can be selected, designed and manufactured with no technical difficulties. To avoid any risk, special type of shield machine which cutter head can be completely rotated into shield body so as to enable cutter replacement done in safe.
