GPR spectral decomposition to monitor cracks in a historic building

The paper deals with the ability of high-frequency multi-component GPR data to detect and monitor evolution of cracks over time. For this purpose, multi component GPR data and advanced processing, based on spectral decomposition of GPR signal, are used. The study takes into account theoretical forward models and actual data acquired on the floor of an ancient building where cracks, with displacements from about 0.001 to 0.02 m and evolving during the time, are present. In-line and cross-line electric field components with x- and y-directed antennas were acquired. The 2x2 data matrix was collected along ten transects over five years. Time lapse analysis of spectral decomposition allows to overcome environmental influence on the data (as the coupling of the antenna-structure depending on the season in which the measurements were collected) and to discover and locate the zones affected by displacement variations which are not detectable by time slices. © RILEM 2013.