DETECTING METHOD FOR DEFORMATION AND COLLAPSE OF GROUND AND CLIFF

摘要

PROBLEM TO BE SOLVED: To provide a method for continuously measuring the movement of the ground in terms of time and space in the event of the deformation and collapse of the ground. ;SOLUTION: In a method for detecting the deformation and collapse of the ground by laying a freely expanding and contracting optical fiber in the ground, an x-axis and a y-axis are provided in the ground, and in a two-dimensional plane in the ground formed by the x- and y-axes, the optical fiber is laid in such a way as to have x-axis and y-axis components. Pulsed beams are made to impinge on one end of the optical fiber, and a coherent wave detecting method is used to detect that a Brillouin scattered beam and a Rayleigh scattered beam which are derived from the distortion of the optical fiber caused by the deformation of the ground return after a time proportional to the distance. The magnitude of the distortion of the optical fiber are detected by the shift of frequency and the site of the distortion is specified from the time required for the impinging beams to return, thus detecting the deformation and collapse of the ground.;COPYRIGHT: (C)1999,JPO