VERTICAL SHAFT AND ITS CONSTRUCTION METHOD

PROBLEM TO BE SOLVED: To construct a large bore vertical shaft even in the soft ground of a city part or the like, to reduce an occupied area of the vertical shaft in the ground part and to reduce a construction period of a diameter enlarged part. SOLUTION: The vertical shaft 1 is constructed by excavating a small bore vertical shaft 10 from the ground part 2, placing a plurality of curved pipe roofs 21 from a lower inner peripheral wall 10a of the small bore vertical shaft 10 toward the radial outside of the small bore vertical shaft 10 over the whole outer periphery so that the tips face downward, excavating the inside of the placed curved pipe roofs 21 to form the diameter enlarged part 20, and excavating under the diameter enlarged part 20 to construct a large bore vertical shaft 30 larger in diameter than the small bore vertical shaft 10. COPYRIGHT: (C)2009,JPO&INPIT