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Role of geophysical surveys in the identification of water escape zones from retention lakes: a case study on a selected object in Upper Silesia

Mieszkowski R., Wójcik E., Kozłowski M., Popielski P.

Studia Quaternaria

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2018

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Vol. 35, Nr 2

121--129

EN

The main scientific goal of this work is the presentation of the role of selected geophysical methods (Ground-Penetrating Radar GPR and Electrical Resistivity Tomography ERT) to identify water escape zones from retention reservoirs. The paper proposes a methodology of geophysical investigations for the identification of water escape zones from a retention fresh water lake (low mineralised water). The study was performed in a lake reservoir in Upper Silesia. Since a number of years the administrators of the lake have observed a decreasing water level, a phenomenon that is not related to the exploitation of the object. The analysed retention lake has a maximal depth between 6 and 10 m, depending on the season. It is located on Triassic carbonate rocks of the Muschelkalk facies. Geophysical surveys included measurements on the water surface using ground penetration radar (GPR) and electrical resistivity tomography (ERT) methods. The measurements were performed from watercrafts made of non-metal materials. The prospection reached a depth of about 1 to 5 m below the reservoir bottom. Due to large difficulties of conducting investigations in the lake, a fragment with an area of about 5,300 m2, where service activities and sealing works were already commenced, was selected for the geophysical survey. The scope of this work was: (1) field geophysical research (Ground-Penetrating Radar GPR and Electrical Resistivity Tomography ERT with geodesic service), (2) processing of the obtained geophysical research results, (3) modelling of GPR and ERT anomalies on a fractured water reservoir bottom, and (4) interpretation of the obtained results based on the modelled geophysical anomalies. The geophysical surveys allowed for distinguishing a zone with anomalous physical parameters in the area of the analysed part of the retention lake. ERT surveys have shown that the water escape zone from the reservoir was characterised by significantly decreased electrical resistivities. Diffraction hyperboles and a zone of wave attenuation were observed on the GPR images in the lake bottom within the water escape zone indicating cracks in the bottom of the water reservoir. The proposed methodology of geophysical surveys seems effective in solving untypical issues such as measurements on the water surface.

2

Zastosowanie metody georadarowej do identyfikacji stref erozji dna rzecznego na przykładzie wybranego odcinka doliny Wisły w Warszawie

Mieszkowski R., Wójcik E., Żmudzin D., Szwarc A., Sosnowska A., Popielski P.

Przegląd Geologiczny

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2017

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Vol. 65, nr 10/2

785--789

EN

In the article the occurrence ofseveral natural thresholds in Vistula River valley was discussed. These forms are stabilizing river channel regime and impeding shipping at the same time. The example of application of ground penetrating radar (GPR) for detecting and identifying the erosion zones in the bottom of the river valley was presented. The investigations were carried out along the chosen section of Vistula River in the vicinity of Gdansk Bridge (Most Gdański) in Warsaw. The survey was conductedfrom a motorboat with the MALA GroundExplorer (GX) georadar system installed with 160 MHz screen antenna. The prospection down to 7.5 m below the water surface was obtained. The applied methodology allowed to obtain radar echograms indicating the following anomalies: from the river bottom, from cohesive soil (includingNeogene clays) andfrom thresholds (noticeably elevatedforms in the bottom). In identifying and interpreting georadar anomalies, archival boreholes data were used.

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Ocena możliwości zastosowania metody georadarowej i elektrooporowej do identyfikacji rozluźnionych stref gruntów niespoistych

Mieszkowski R., Zawrzykraj P., Żmudzin D., Wójcik E., Popielski P.

Przegląd Geologiczny

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2017

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Vol. 65, nr 10/2

779--784

EN

The results of the possibility of geophysical methods application (such as geoelectrical ones, including ground penetrating radar and electrical resistivity tomography) to identify areas of loose sands were presented in the article. Registered anomalies obtained from geophysical survey have been verified by geological and engineering tests (drillings and dynamic probing). Measurements were carried out along the part of the lateral earth dam, consisting of man-made soils with a thickness of approximately 7 m and underlying alluvial medium grained sands. The results obtained from the geophysical survey and direct assessment of density by means of dynamic probing allowed to demonstrate the relationship between a specific type of geophysical anomalies and the density of non-cohesive man-made soils.

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Przykład oceny antropogenicznych zmian podłoża gruntowego metodą georadarową

Konopko M., Wysocka M.

Inżynieria i Budownictwo

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2017

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R. 73, nr 3

164--165

PL

Przedstawiono przykład możliwości wykorzystania techniki georadarowej do określenia dokładnego położenia zlikwidowanej studni, a także do identyfikacji siatki zbrojeniowej w warstwie betonowej.

EN

The detection and the location of anthropogenic objects lying in changeable subsoil can cause some problems. The joint reinforcement in concrete layer was shown.

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Numerical modeling of GPR field in damage detection of a reinforced concrete footbridge

Lachowicz J., Rucka M.

Diagnostyka

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2016

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Vol. 17, No. 2

3--8

EN

The paper presents a study on the use of the ground penetrating radar (GPR) method in diagnostics of a footbridge. It contains experimental investigations and numerical analyses of the electromagnetic field propagation using the finite difference time domain method (FDTD). The object of research was a reinforced concrete footbridge over a railway line. The calculations of the GPR field propagation were performed on a selected cross-section of the bridge. Three different damage scenarios (i.e. one missing rebar and two air voids with different shapes and locations) were investigated in FDTD simulations. Numerical GPR maps were compared with results of in-situ GPR surveys for the healthy footbridge.

PL

W artykule przedstawiono użycie metody georadarowej w procesie diagnostyki kładki dla pieszych. Praca zawiera badania doświadczalne oraz analizy numeryczne propagacji pola elektromagnetycznego z wykorzystaniem metody różnic skończonych w dziedzinie czasu. Przedmiotem badań była żelbetowa kładka dla pieszych usytuowana nad torami kolejowymi. Obliczenia wykonano na przykładzie wybranego przekroju poprzecznego kładki. Rozważono trzy różne scenariusze uszkodzeń, tj. brak jednego z prętów zbrojeniowych oraz dwie pustki powietrzne o różnych kształtach i lokalizacjach. Wyniki symulacji porównano z wynikami badań doświadczalnych przeprowadzonych na nowo wybudowanym obiekcie.

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Application of GPR method in diagnostics of reinforced concrete structures

Lachowicz J., Rucka M.

Diagnostyka

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2015

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Vol. 16, No. 2

31--36

EN

This paper presents an application of the ground penetration method (GPR) for diagnostics of reinforced concrete structures. In situ measurements were conducted for three civil engineering structures: the ground floor structure, the abutment of the railway viaduct and the concrete well. The dual polarized ground penetrating radar with the antenna operating at a center frequency of 2 GHz was used for GPR surveys. Three different methodologies of measurements were analyzed. The results showed that the GPR method enables quick and efficient diagnostics of concrete structures. Based on GPR results it is possible to identify the distribution and amount of reinforcement, as well as the thickness of the concrete layer.

PL

W artykule przedstawiono zastosowanie metody georadarowej do diagnostyki konstrukcji żelbetowych. Pomiary polowe przeprowadzono na trzech obiektach inżynierskich: konstrukcji podłogi posadowionej na gruncie, przyczółku wiaduktu kolejowego oraz rurze betonowej. Badania doświadczalne wykonano za pomocą georadaru z anteną bipolarna o częstotliwości 2 GHz. W pracy przedstawiono trzy typy metodologii pomiarów georadarowych. Przeprowadzone testy wykazały, że metoda georadarowa umożliwia szybką i wydajną diagnostykę konstrukcji żelbetowych. Na podstawie uzyskanych wyników badań była możliwa identyfikacja rozkładu i ilości zbrojenia, a także grubości warstw betonu.