tunnel boring machine and method for operating a tunnel

摘要

A tunnelling apparatus composed of a plurality of elongate planks arranged side-by-side on a circumferential path to form a shield of circular configuration. The planks are separated into two relatively movable groups with the individual members alternately staggered so that a member of one group is disposed between two members of another group. Each group of planks is supported on three axially spaced expandible ring devices used to selectively brace the planks against the tunnel wall. Rams are provided between the rear support device of one group and a central support device of the other group so that the groups can be alternately advanced with the planks of said one group forming a forward support and the planks of said other group forming a rear support.