TUNNEL CONSTRUCTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a method capable of constructing a tunnel in water springing or weak natural ground in a short construction period without complicating execution work. SOLUTION: A small tunnel 2 having a cross section smaller than a design cross section of a finished tunnel 1 is precedently constructed in the natural ground G of an installing object of the finished tunnel 1, improving execution work is applied to the natural ground G outside of a construction object position of a peripheral wall surface 1a of the finished tunnel 1 from the inside of the small tunnel 2, and afterwards, the width of the small tunnel 2 is expanded to form the finished tunnel 1.