Removal method of existing tunnel structure by box roof method

摘要

To provide a method of partially removing an existing tunnel structure from the existing tunnel structure, and then constructing a new tunnel structure.SOLUTION: In a construction of a new tunnel structure, a box-shaped roof 7 is installed penetrating in a construction section, at a position coinciding with an outer edge of the new tunnel structure from a start side 4 and an arrival side 5 on both sides as protective work for the construction section; a casing body for the new tunnel structure is built on the start side 4; and the box-shaped roof 7 and the casing body are pushed out to the arrival side. In removal of the existing tunnel structure, the existing tunnel structure is cut and separated, a part 1d overlapping with the new tunnel structure below the box-shaped roof is temporarily received by a supporter 26 with rollers; a lower part of the box-shaped roof 7 and a cut and separation part of the existing tunnel structure are locked; and the part 1d overlapping with the new tunnel structure is extruded together with the box-shaped roof 7 and the casing body for the new tunnel structure, and is pushed out to the arrival side 5 and disassembled.SELECTED DRAWING: Figure 1