CONSTRUCTION OF WIDENED PART FOR TUNNEL IN GREAT DEPTH

摘要

PURPOSE:To make structure stabilized by a method wherein excavation is made on the lateral side of a tunnel main body to form a widened part in radius of curvature smaller than that of the tunnel main body, and the excavation is formed in an ovally-shaped section with lining walls constructed to make the widened part integral with the tunnel main body. CONSTITUTION:Hardening agent is injected from the main body A of a tunnel into natural ground 3 on the lateral side of a part where widening is to be made for the tunnel. After the natural ground is solidified and stabilized, segments for the part to be widened of the tunnel main body A are removed and a widened part B is constructed by means of manual excavation or the like. Lining walls 4 for uniting of the main body A and the widened part B are formed of precast concrete or the like in ovally-shaped section, and prestressing steels 5 are inserted into the concrete in the circumferential direction of the section. Then prestressing is made in the circumferential direction with tension applied to the prestressing steels. Thereby the widened part that is structurally stable and excellent in load-bearing capacity can be constructed to the tunnel without allowing unserviceableness in space to become large.