INTERNAL-CONTACT TYPE SET SHIELD MACHINE

摘要

PROBLEM TO BE SOLVED: To construct a tunnel which is continuously extended without changing any of lines, when the cross section is changed, by using a set shield machine with a common cutter. SOLUTION: A set shield machine consists of a master shield machine 1 with a large diameter and a subsidiary shield machine 2 with a smaller diameter provided therein. The subsidiary shield machine 2 is arranged in internal contact with the inner face of the master shield machine 1. A drilling disc 3 with a diameter equal to that of the subsidiary shield machine 2 is arranged in front of the master shield machine 1 so that the drilling disc 3 can be oscillated for drilling when the master shield machine 1 is moved and the drilling disc can be rotated around the center of a circle for drilling when the subsidiary shield machine 2 is moved.