| 摘要 |
PROBLEM TO BE SOLVED: To provide a vertical shaft constructing method that can reduce cost and term of works for construction while preventing troubles such as boiling of sand or heaving of ground even though the depth of embedment is set short. SOLUTION: The vertical shaft excavating method is such that a ditch 2 is constructed with the inside of an earth retaining wall 1 provided under the ground excavated by underwater excavation to a specified depth and after that, a bottom board 41 for a vertical shaft is provided at the bottom of the ditch 2 and a side wall for the vertical shaft is provided at the inner circumference of the earth retaining wall 1 respectively by underwater work. After the ditch 2 is constructed, a plurality of cylindrical precast segment rings are connected with one another in the vertical direction and at least a part of the inner circumferential part 32 of the side wall is constructed under water before discharging water collecting in the ditch 2. Then, at least a part of the outer circumferential part 35 of the side wall is constructed under water with concrete placed into a gap between the earth retaining wall 1 and at least a part of the inner circumferential part 32, and thereby at least a part of the side wall is constructed under water. After that, the bottom board 41 is constructed under water and water inside the side wall is discharged.
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