METHOD FOR DETERMINING CENTER OF INNER CIRCUMFERENTIAL SURFACE OF TUNNEL, AND METHOD AND INSTRUMENT FOR MEASURING DETERIORATION IN INNER CIRCUMFERENTIAL PART OF TUNNEL

摘要

PROBLEM TO BE SOLVED: To provide a method for determining the center of an inner circumferential surface of a tunnel prior to scraping a deteriorated portion in an inner circumferential part of the tunnel, a tunnel with a circular cross-section in particular. SOLUTION: This method is used for determining the center of the inner circumferential surface 12 of the tunnel 10. A distance measuring sensor 16 mounted on a front end part of an arm 14 is rotated on an axis RA of rotation to measure the distance from the axis to the surface of the tunnel at three or more positions in the circumferential direction of the tunnel. Then, the position of the axis RA is adjusted based on the results of the measurement so as to agree with the real center axis AA of the tunnel.