Determination of local objects with changing geometry in a wave field of gpr

Abstract

The article deals with problem of GPR using for local bodies searching, such as engineering communications. In order to determine the evaluation criteria for the radarograms of the desired objects occurrence depth, a laboratory experiment was performed. In the experiment the conditions of occurrence in sandy soil of linearly elongated pipelines from different materials were recreated. The local objects change their spatial location due to the rotation around its axis in 10° step. For each turning position with the help of high-frequency GPR antenna obtained radar images, which allows to estimate the depth of the desired object by the analysis of diffracted wave hyperboles. As a result of research it is established that the spatial position of linearly elongated local objects has a significant impact on the phenomenon of electromagnetic wave diffraction. It is shown that at the intersection of the communication line at an angle of less than 60% such object ceases to be point and hyperbole is not formed. The use of a standard approach to determine the permittivity of the host medium on the hyperbole formed under conditions not perpendicular to the intersection of the direction of the route line can lead to an error of up to 50%. The findings allow us to conclude about the need to perform a series of profiles when working with linearly extended engineering communications, as well as the inadmissibility of determining the dielectric constant on radar images using single hyperbolas.