METHOD AND DEVICE FOR DETECTING ASSEMBLY POSITION OF SEGMENT

PROBLEM TO BE SOLVED: To efficiently assemble segments by easily and correctly positioning new hexagonal segments with respect to existing hexagonal segments in executing linings by the hexagonal segments on a wall surface of an excavated tunnel. SOLUTION: When new hexagonal segments 1B held by a segment hanger of an erector are assembled to existing hexagonal segments 1A, a slit beam is irradiated between an inclined edge on both sides of the new hexagonal segments 1B and an inclined edge of the existing hexagonal segments 1A opposite thereto to project a straight irradiation part on the existing hexagonal segments 1A side and a straight irradiation part on the new hexagonal segments 1B side on a monitor screen. An operator operates the erector watching the monitor screen to assemble the new hexagonal segments 1B so that the gaps in the vertical direction and in the right-to-left direction between the edges opposite to each other of the straight irradiation parts on both sides of the new hexagonal segments 1B.