To provide a widening method for a tunnel capable of economically constructing the tunnel with a widened part.
For a general pit 14a, after standard sectional segments 9a are assembled in a ring shape in a skin plate 2, an outer shell 12 is fixed to a position adjacent to the area on the outer peripheral surface of the ring-shaped assembly having a widened section 1b, and a filler 13 is filled in hollow parts to form filled blocks 11. Then, steps for excavating by a shield machine 1 are repeated in order. For an enlarged pit 14c, enlarged sectional segments 9c are assembled in a ring shape in the skin plate 2 so that the end faces thereof abut on an enlarged section formed by the standard sectional segments 9a positioned at the forwardmost end of a shield tunnel and the filled blocks 11, and steps for excavating by the shield machine 1 are repeated.
YOMO HIROAKI
KAWASHIMA KEISUKE
Tadashi Takahashi
Takashi Watanabe
Masakazu Aoyama
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