From April 26 to April 30, 2021, Gelendzhik hosted the 17th International Scientific and Practical Conference and exhibition "Engineering and Ore Geophysics", held annually by the European Association of Geoscientists and Engineers (EAGE). Specialists and scientists from 100 countries discussed the application of geophysical methods in engineering surveys, exploration and mining. On April 28, in the framework of the section "Georadar Technologies", the experts of the FAA "ROSDORNIA" presented the results of comparative tests of various types of georadar equipment used for the inspection of highways. The analysis of the data obtained showed the advantages of domestic solutions over ground-penetrating radars from the USA and Sweden.
Pulse-type ground-penetrating radars (including American and Swedish production), as well as linear-frequency and step-frequency modulation took part in the tests. In total, seven samples of equipment with contact and contactless antennas operating at various frequencies from 250 to 2000 MHz were tested. Final report "Analysis of the results of comparative tests of georadolocation equipment on the experimental section of the highway" was prepared by the head of the Department of Methods of designing highways of the Federal State Budgetary Institution "ROSDORNII", Doctor of Technical Sciences, Professor Alexander Kulizhnikov and Head of the Department of Innovative Technologies in Engineering Research, Ph.D. Roman Eremin.
"The tests were conducted in order to identify the optimal designs of ground-penetrating radars, as well as to determine the most effective methods of performing ground-penetrating radar work to solve road problems. Among them is the determination of the thickness of the layers of road pavement, the identification of signs and the location of weakened zones," says Alexander Kulizhnikov.
Mobile road laboratories developed at ROSDORNIA based on a van, which were put into operation in 2020 as part of the implementation of the national project "Safe High-quality Roads", were used for testing.
To determine the thickness of the pavement layers, both the traditional method according to GOST R 58349-2019 (through the refinement of the dielectric constant by comparing radar images and the results of control drilling) and alternative methods were used technologies: the method of amplitudes, the method of average values and the method of reflecting interlayers. At the same time, the traditional method provided the smallest average deviation in absolute value.
Identification of signs and determination of the location of weakened zones with each type of GPR was carried out according to the methodology developed for it, including:
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By attributive analysis of the signal amplitude and the frequency composition of the recording, as well as the analysis of the axes of in-phase;
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With the help of visual analysis of radarograms by changes in amplitude, shape and attenuation of the signal;
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By the method of texture analysis and digital image processing based on deviations of signal and image attributes;
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By analyzing the backscattering field by deviations of the signal attributes;
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Using neural networks;
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Identification of zones of compaction and decompression by deviations of attributes of the phase image;
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By searching for drawdowns in the layers of pavement by mathematical focusing using radar technology with synthesis apertures.
The attributive method of amplitude-frequency analysis showed the greatest reliability. "In general, domestic ground-penetrating radars with stepwise (linear) frequency variation gave better results in comparison with pulsed ones. Nevertheless, for a final affirmative conclusion, it takes some time to fine-tune the hardware and software for it," Alexander Kulizhnikov notes.
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EAGE is a professional association of geologists, geophysicists, engineers and geoscientists, founded in 1951 and uniting more than 19 thousand members from more than 100 countries of the world. The European office of the association is located in the Netherlands, regional offices operate in Moscow, Dubai, Kuala Lumpur and Bogota.