Shield machine

摘要

A shield machine for enlarging a portion of an existing tunnel includes an inner and outer double cylinder shaped shield machine body with a cylindrical outer shield portion and a cylindrical inner guide portion designed to be driven in an axial direction of an existing tunnel and along an outer circumferential surface of primary assembly segments lining the existing tunnel. Jack members are provided for pushing forward the shield machine body by receiving a reaction from a reaction member such as secondary assembly segments lining a constructed enlarged tunnel. A scraper member is positioned adjacent to the inner guide portion for removing a back-filling agent on the outer surface of the primary assembly segments.