| 摘要 |
PROBLEM TO BE SOLVED: To provide a tunnel face monitoring method that expands a range of measurement to a tunnel face using a laser distance meter and readily reduces a frequency of replacement.SOLUTION: A tunnel face monitoring method is for monitoring an extrusion amount of a tunnel face 5 using a laser distance meter 3 installed in an interior space A of a tunnel 1, and includes the following steps for: tunnel face measurement in which a distance to the tunnel face 5 is measured using the laser distance meter 3; and replacement in which the laser distance meter 3 is removed and installed again at a position closer to the tunnel face 5, when the tunnel face 5 is advanced in a repeated tunnel face advancement process and the distance between the laser distance meter 3 and the tunnel face 5 increases, but accuracy of distance measurement by the laser distance meter 3 is insufficient. If the laser distance meter 3 was re-installed in the replacement step, an ND filter 31 is fitted on the laser distance meter 3 for dimming a laser light L or a reflection light R. If dimming is judged as unnecessary for distance measurement as a result of the tunnel face 5 advancement, the ND filter 31 is removed from the distance meter. |
