| 摘要 |
PROBLEM TO BE SOLVED: To accurately estimate bending strain at low costs and precisely evaluate a safety factor.SOLUTION: At a first step S1, a first measuring apparatus 2 is introduced at any position in a buried pipe 3, a distance between a first distance measuring device 2A of the first measuring apparatus 2 and an inner surface of the buried pipe 3 is determined to obtain radii of curvature 1/r1 to 1/rn of the deformed pipe based on determined measurement values d1 to dn. At a second step S2, an elasticity theory of a curved beam is applied to the radii of curvature 1/r1 to 1/rn of the deformed pipe obtained at the first step S1 to estimate the strain of the buried pipe 3, and at least one strain of breaking strain and yield strain is obtained in advance for each buried pipe 3. Based on comparison between the bending strain of the buried pipe 3 estimated at the first step S1 and the second step S2 and the previously obtained strain, a quantitative safety factor of the target buried pipe 3 is evaluated. |
