| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable the highly accurate detection of the movement of earth and sand by embedding an optical fiber cable connecting weights in earth and sand of a river dike and measuring the distribution of distortion exerted on the optical fiber cable. SOLUTION: An earth and sand movement detecting sensor is constituted by embedding an optical fiber cable 1 in earth and sand of a river dike, for example, along the river dike, embedding weights 2 connected on one side of the cable 1, for example, on the toe side of the slope, and providing a distortion distribution measuring device 3 to measure the distribution of distortion exerted on the cable 1. The cable 1 may be placed in the vicinity of the toe of the slope. An optical-fiber distortion distribution measuring device to irradiate an optical fiber with short-pulse laser beam and to detect scattered Brillouin scattered light is, for example, used as the measuring device 3 to obtain the distribution of distortion along the length of the cable 1 by a predetermined method. By the above, it is possible to detect the elongation of the cable 1 which occurs in the case that the weights 2 are moved with the movement of the earth and sand.</p> |
