TUNNEL EXCAVATION METHOD, CONSTRUCTION METHOD OF TUNNEL ENTRANCE BRANCH/CONFLUENT WIDTH EXPANDING PART USING THIS METHOD AND TUNNEL ENTRANCE BRANCH/CONFLUENT WIDTH EXPANDING PART CONSTRUCTED THEREBY

摘要

PPROBLEM TO BE SOLVED: To provide a construction method of a tunnel entrance branch/confluent width expanding part, capable of securing maintenance of a social environment and a surrounding environment by restraining excavation surplus soil to a necessary minimum, capable of performing safety construction by minimizing influence on the surrounding ground, and capable of simplifying joining work by shortening a joining distance between a main track tunnel and an entrance tunnel. PSOLUTION: This construction method includes a process of connecting a U-shaped tunnel 18 and the main track tunnel 10 after the U-shaped tunnel 18 is approached in a state of straddling on the two main track tunnels 10 by a U-shaped shield machine, a process of constructing a top slab part 21 of the entrance tunnel 14 by placing concrete in the U-shaped tunnel 18, and a process of forming a branch/confluent width expanding part 16 by connecting to the main track tunnel 10 by constructing a residual skeleton 42 of the entrance tunnel 14 by excavating the natural ground under the top slab part 21. PCOPYRIGHT: (C)2008,JPO&INPIT