Segment and tunnel covering works manner null for tunnel covering works

摘要

PURPOSE:To facilitate the handling of a segment before lining construction and during it by contriving the structure of the segment in the case where precedent excavation is executed at the position of a tunnel lining, and the inside of the tunnel is excavated after the formation of a segment ring, and the rationalization of lining construction work is thereby realized. CONSTITUTION:Concrete 7 is post-placed inside a steel shell to form a composite segment 1. The steel shell is set up in a precedent excavating section at the position of tunnel lining, and the steel shells are mutually assembled into a ring-shape. Rigidity reinforcing ribs 11 extending in the axial direction of tunnel are provided on the insides of a steel plate 2 on the side of the natural ground and of a steel plate 3 on the side of an internal cavity which compose the steel shell, and rigidity reinforcing ribs 12 extending in the radial direction of the tunnel are provided on side plates 4, and the steel shell before filling up the concrete 7 can thereby resist against the jacking thrust of a shielding machine. In addition, a rigidity reinforcing rib 14 extending in the peripheral direction of a segment ring is provided on the insides of the steel plate 2 on the side of the natural ground and of the steel plate 3 on the side of the internal cavity, and made to resist against the temporary load of the natural ground at the time of execution together with the other rigidity reinforcing ribs 11, 12.