GPR Fractures Detection Using Changeable Antennae Orientation

Abstract

Georadar recordings depend on the polarisation of the electromagnetic wave emitted from the transmitter antenna, polarisation of the wave reflected from the investigated object and from the different orientations of the set of transmitter-receiver antennae. Therefore the authors carried out in the paper short analysis of possibilities and limitations of using of measurements with changeable orientation of antennae for GPR detection of fractures in the selected post-mining area in Poland. The GPR investigation using variable antennae geometry was carried out in the town of Siersza (Upper Silesia region, Poland) where sinkholes and subsidence areas induced by the shallow mining exploitation was observed on the earth surface. For co-pole and end-fire antennae polarisations some differences in recorded radargrams were distinguished, which delivered additional information about anomalies distribution in the rock mass. The recordings for cross-pole polarisation seem to be the least useful for fractures detection. Main conclusion drown on the basis of the presented results should be as follow: GPR detection of fractures distribution in the rock mass should be carried out using multi-channel systems, where in several channels antennae with different orientations should be connected.