Contribution of radar measurements to the inspection and condition assessment of railway bridges – case study at a historic masonry arch bridge in Oleśnica/Poland

Abstract

Ground Penetration Radar (GPR) as a non-destructive (NDT)-method can be applied to obtain detailed information about the inner structure and condition of bridges without damaging the structure. In this paper the capabilities and limitations of the application of the fast inspection technique GPR will be demonstrated. In addition to GPR investigations, geoelectrical measurements, coring and petrophysical investigations have been carried out. The investigated railway bridge in Oleśnica is a typical European masonry arch bridge (age, construction and span length). It shows typical damage to the masonry arches such as increasing salt concentration, destruction, material losses and longitudinal cracks. Radar measurements were carried out with two main objectives: (1) Identification of basic geometric dimensions of the bridge and identification of construction details; (2) Evaluation of the condition of the masonry, such as mechanical damage (e.g. cracks) or variation of the moisture content. Radar antennas of different frequencies (having different penetration depths) have been used to estimate the thickness of the walls. Because of the high attenuation in the inner masonry structure the measurements have not produced satisfying results, but the radar measurements have been successfully applied to investigate the moisture distribution in the masonry. These results have been verified by coring and through geoelectrical measurements. Cracks were studied at two testing areas at one wing wall of the bridge using an automatic 2D radar scanning system. The radar data were processed using advanced data processing tools like FT-SAFT reconstruction and data fusion. The processing sequence allowed the creation of high-resolution depth sections (C-Scans).

A Review of GPR Application on Transport Infrastructures: Troubleshooting and Best Practices

“…Alani et al [132], Fauchard et al [135], Pérez-Gracia et al [140], Solla et al [128][129][130][131]137,144], Lubowiecka et al [142] and Arêde et al [145] employed a combination of low and medium (500-600 MHz) center frequency antennas to evaluate the stone masonry health assessment. Additionally, higher frequencies were used in the 800 MHz to 2 GHz frequency range to estimate the thickness of masonry walls and arches [124,132,[134][135][136]138,140,141,143].…”

“…Orbán and Gutermann [124] combine GPR, sonic testing, and infrared tomography (IRT) to investigate hidden geometry, voids and cracks and moisture distribution in masonry and fill, as well as to define wet areas. Trela et al [134] use geoelectrical measurements of spectral induced polarization (SIP), combined with GPR, to evaluate the moisture distribution inside the masonry. Fauchard et al [135] present a combination of GPR and electrical resistivity tomography (ERT).…”

Characterization of a Romanesque Bridge in Galicia (Spain)

“…GPR has proved to be a useful and fast method for nondestructive evaluations of modern concrete bridges (Scott et al 2003;) as well as of historical masonry structures (Palieraki et al 2008;Binda et al 2007) including masonry arch bridges (Diamantini, Giannopoulos, and Forde 2008;Trela et al 2008;Lubowiecka et al 2009;Orbána and Gutermannb 2009 by different center frequencies: 800, 500, and 250 MHz. The first survey is fully described in Arias et al (2007) and Lorenzo et al (2007).…”

Non-destructive testing for the analysis of moisture in the masonry arch bridge of Lubians (Spain)

“…Infrared thermography is an NDT that has been widely used in masonry structures for defects detection, such as delamination , voids and cracks and humidity areas , the latter being the most frequent cause of the former defects. On the other hand, GPR has also been used in the detection of water inside structures given the fact that water provokes attenuation in the signal . Thus, the combination of these techniques can be applied to the characterization and monitoring of historical structures, as shown in some published studies , which enables inspectors to obtain a complete view of the real state of the structure.…”