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1

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

Identyfikacja zagrożenia wystąpienia przebić hydraulicznych w podłożu obiektów kubaturowych za pomocą nieinwazyjnych metod badawczych

Błaszczak A., Zając K., Skutnik Z., Mieszkowski R., Tryfon-Bojarska A., Koch D.

Inżynieria Morska i Geotechnika

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2018

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nr 3

229--235

PL

Zastosowanie tomografii elektrooporowej (ERT) do określania położenia stropu warstw nawodnionych piasków. Skorelowanie profili elektrooporowych z wynikami wierceń i sondowań geotechnicznych. Wykonanie mapy obszarów w których może dojść do wystąpienia niekorzystnych zjawisk hydraulicznych w trakcie prowadzenia prac budowanych. Doprecyzowanie projektu konstrukcji, a także projektu odwodnienia wykopu na podstawie wyników prac w celu zabezpieczenia się przed negatywnym działaniem wody.

EN

Application of electro resistivity tomography (ERT) for determining the position of the upper strata of saturated sand layers. Correlation of electro resistivity profiles with the results of geotechnical drilling and soundings. Preparation of the map of areas in which adverse hydraulic phenomena may occur during construction works. Improvement of the design of the structure, as well as the project of drainage the excavation on the basis of the results of the work in order to protect against the negative effects of water.

3

An attempt to integration of different geophysical methods (magnetic, GPR and ERT); a case study from the late Roman settlement on the Island of Rab in Croatia

Welc F., Mieszkowski R., Lipovac-Vrkljan G., Konestra A.

Studia Quaternaria

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2017

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Vol. 34, Nr 1

47--59

EN

In 2016 within the RED Project Roman Economy in Dalmatia: production, distribution and demand in the light of pottery workshops, 5 selected areas around the Podšilo Bay were geophysically surveyed. During the fieldworks in the Lopar protected area, located in the northeastern part of the Island of Rab a gradiometer, ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) were used. The main aim of the project was to document presence of the Roman architecture in two areas of the bay’s hinterland as suggested earlier by finds of pottery and glass. Geophysical studies conducted in the Lopar area revealed presence of underground remains of ancient structures, probably from the late Roman period and connected with a ceramic production centre at the present seashore. The most interesting results were obtained for the area no. 4, the site where magnetic, georadar and ERT surveys revealed an ancient regular building at 0.4–0.6 m depth. The survey performed in the Lopar area clearly indicates that integration of different geophysical methods enables detailed and effective identification of buried archaeological structures.

4

Stateczność zbocza i zagrożenie osuwiskowe w świetle kompleksowych badań geologicznych

Gawriuczenkow I., Kaczmarek Ł., Kiełbasiński K., Kowalczyk S., Mieszkowski R., Wójcik E.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2017

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Vol. 26, No. 1

85--98

PL

W artykule przedstawiono studium przypadku oceny stateczności zbocza zlokalizowanego w południowej Polsce, w obszarze o skomplikowanej budowie geologicznej. Zaproponowano wieloetapową metodologię oceny stateczności zbocza. Zastosowane komplementarne techniki badawcze pozwoliły uzyskać dokładną i rzetelną ocenę stateczności analizowanego zbocza, a przedstawiona wieloetapowa procedura analizy uwarunkowań stateczności umożliwiła uwzględnienie różnych cech i mechanizmów destabilizujących stan równowagi, co pozwala na prognozowanie kierunków zagospodarowania przestrzennego.

EN

The multistage methodology of the slope stability analysis, based on a case study, is presented in the paper. The study area is located in southern Poland, where geological conditions are complex. A numerous complementary research techniques that were applied provided reliable and exact assessment of equilibrium state of the slope. The results have shown that presented multistep procedure takes into account various destabilizing factors and therefore enables the prediction of the future spatial planning.

5

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.

6

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.

7

Reading of ground-penetrating radar (GPR) images of prehistoric flint mine; case study from Krzemionki Opatowskie archaeological site in central Poland

Welc F., Mieszkowski R., Conyers L. B., Budziszewski J., Jedynak A.

Studia Quaternaria

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2016

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Vol. 33, Nr 2

117--130

EN

Geophysical surveys conducted in order to map tunnels and vertical shafts at the Neolithic chert mining field Krzemionki used a ground-penetrating radar (GPR) to test hypotheses regarding orientation, depth and subsurface complexity of these voids. Using two-dimensional reflection profiles the vertical shafts, now mostly filled with lithic debris, were easily visible. Amplitude mapping visualized debris at shaft margins as well as a collapsed material inside the voids. Some shallower horizontal tunnels were also visible as sub-horizontal planar reflections generated from both ceiling and floors of these void spaces. Extension of these interpretations to un-mapped areas of the ancient mining district and complexity of these prehistoric mining features could be examined to determine excavation intensity and exploitation techniques used during the Neolithic.

8

Application of electrical resistivity imaging and land surveying in the analysis of underground construction impact on the Warsaw Scarp

Kaczmarek Ł., Mieszkowski R., Woźniak M., Dybciak T.

Studia Quaternaria

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2016

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Vol. 33, Nr 2

83--90

EN

The paper presents the analysis of the II Underground Line construction’s impact on the Warsaw Scarp with the use of the electrical resistivity imaging (ERI, also known as the electrical resistivity tomography) and further total station position measurements. The underground passes under the scarp perpendicular in the area of Dynasy Street 6, in Downtown district. The electrical resistivity imaging was performed for recognition of the geological structure and a potential landslide surface or zone. The gradient system was used during the prospection. In these analyses, the longitudinal section was 40 m long, and the depth of survey amounted to 6 m. In the case of the 200 m long transverse section, the resulted depth of survey was 30 m. The geophysical image of the longitudinal section, does not contain loosening soil zones, which could indicate slip surface. Next, total station measurements, which were tied to the archival geodetic observations’ results, were carried out. The aim of the measurements was to verify the activity of the horizontal and vertical displacements. The TBM excavation process led to summary vertical displacements up to approx. 24 mm and horizontal displacements amounting to approx. 13 mm. To sum up, the current land surveys reveals minor underground line’s construction impact on the scarp displacement. Nevertheless, the sensitive urban environment requires further monitoring, especially that the operation loads can result in displacement rate change.

9

Rola obrazowania elektrooporowego w uszczegółowieniu skomplikowanej budowy geologicznej wzgórza Morasko w Poznaniu

Pacanowski G., Sokołowska M., Mieszkowski R.

Przegląd Geologiczny

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2016

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Vol. 64, nr 4

238--244

EN

The paper focuses on the problem of developing reliable geological models based on point data from boreholes and two-dimensional results of geophysical surveys with application of electrical resistivity tomography (ERT). The study area was the Morasko Hill in Poznañ (Poland), located within frontal moraines overlying Pliocene clays with a top surface strongly deformed glaciotectonically. Due to the presence of these deformations, the study area shows a complex geological structure. Analysis of archival boreholes indicates that the top surface of the Pliocene clays is extremely variable, hampering unequivocal determination of geological boundaries. ERT measurements were used to recognize the detailed geological structure of the area. Next, additional boreholes and CPTU soundings were made in selected localities characterized by anomalies in the distribution of electrical resistivity values. Following the drillings and soundings, and the results of the geophysical survey were reinterpreted. Such complex methodology of field work, including geophysical and geological surveys, has allowed us to present a reliable geological model of the area, in which the ERT results coincide with the drilling results. In practice, the preparation of an appropriate geological model, particularly in the vicinity of escarpments and slopes, is indispensable for designers of construction objects in the selection of foundations and analysis of slope stability.

10

Analiza możliwości zastosowania metody tomografii elektrooporowej (ERT) do rozpoznania miąższości pokrywy laterytowej

Pacanowski G., Czarniak P., Piechota A., Mieszkowski R.

Przegląd Geologiczny

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2016

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Vol. 64, nr 4

245--253

EN

The paper discusses the problem of determining the thickness of a laterite cover using electrical resistivity tomography (ERT) in a selected area of the Seram Island in Indonesia. Seram Island lies in the tropical zone between the Seram and Banda seas. The laterite covers are rich in nickel, cobalt, iron and other metals. Concentrations of these metals in the laterites are high enough to form economic deposits. A significant part of the report concerns the measurement technique (ERT method) in difficult climatic (high humidity and temperature) and topographic conditions (equatorial jungle with significant variations in elevation) and the methods of processing and interpretation of the acquired data. The problem seems very interesting, because geophysical prospecting is currently more and more often conducted in poorly accessible regions of the world. Additionally, there are no sufficient and commonly available publications that would allow us to get acquainted with local measurement problems by potential contractors of similar geophysical investigations. The primary result of the geophysical survey was to determine the electrical resistivity of bedrock and laterite. This was the basis for the development of sections of electrical resistive distribution for the ERT profiles, which enabled to estimate the depth to the crystalline basement and the laterite thickness. It also facilitated to produce a map of laterite thickness, which may be an important material to develop the concept of searching and mining of nickel and cobalt ore.

11

Interpretacja wyników badań geofizycznych metodą GPR na podstawie pomiarów nasypów kolejowych

Maślakowski M., Piotrowski T., Mieszkowski R.

Materiały Budowlane

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2016

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nr 2

12--14

PL

Artykuł dotyczy możliwości interpretacji wyników badań uzyskanych metodą nieinwazyjną GPR (Ground Penetrating Radar). Na podstawie danych uzyskanych z badań nasypów kolejowych wskazano problemy z tym związane. Przedstawiono przykładowe przyczyny powstawania zakłóceń na echogramach GPR, które nie są związane ze środowiskiem gruntowo-wodnym, a jedynie z infrastrukturą kolejową. To sprawia, że skuteczność metody GPR jest szacowana na nie więcej niż 50% i wymaga potwierdzenia konwencjonalnymi badaniami geotechnicznymi.

EN

The article concerns the possibility of interpreting the test results obtained using a nondestructive GPR (Ground Penetrating Radar) measurement. On the basis of data obtained from studies on railway embankments, associated problems were indicated. There are presented examples of the causes of disturbances on GPR echograms that are not associated with the soil and its aquatic conditions but only with the presence of railway infrastructure. This makes that the GPR method efficiency is estimated at level not more than 50% what requires confirmation in conventional geotechnical tests.

12

A new Triassic-Jurassic section in the southern part of the Holy Cross Mts. (Poland) implications for palaeogeography

Kozłowska M., Barski M., Mieszkowski R., Antoszewska A.

Geological Quarterly

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2016

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Vol. 60, No. 2

365--484

EN

Sedimentological, stratigraphical and geophysical studies across a new Triassic-Jurassic transition section in the Holy Cross Mts., Poland have revealed a large sedimentary hiatus embracing the entire latest Triassic–Early Jurassic – earliest Middle Jurassic time interval and yielded new data on the Triassic fluvial system and on Middle Jurassic shallow marine sedimentation. The presence of organic-walled dinoflagellate cysts allowed a precise age assignment of the black clay facies. Regional discussions and comparisons may be made with other areas with a similar depositional environment in Poland. For the first time a counterpart of the “Kościeliskie Beds” lithostratigraphic unit is proposed to exist in the Holy Cross Mts. area.

13

Mnin restraining stepover – evidence of significant Cretaceous–Cenozoic dextral strike-slip faulting along the Teisseyre-Tornquist Zone?

Konon A., Ostrowski S., Rybak-Ostrowska B., Ludwiniak M., Śmigielski M., Wyglądała M., Uroda J., Kowalczyk S., Mieszkowski R., Kłopotowska A.

Acta Geologica Polonica

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2016

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Vol. 66, no. 3

429--449

EN

A newly recognized Mnin restraining stepover is identified in the Permo-Mesozoic cover of the western part of the Late Palaeozoic Holy Cross Mountains Fold Belt (Poland), within a fault pattern consisting of dextral strikeslip faults. The formation of a large contractional structure at the Late Cretaceous – Cenozoic transition displays the significant role of strike-slip faulting along the western border of the Teisseyre-Tornquist Zone, in the foreland of the Polish part of the Carpathian Orogen. Theoretical relationships between the maximum fault offsets/ mean step length, as well as between the maximum fault offsets/mean step width allowed the estimation of the values of possible offsets along the Snochowice and Mieczyn faults forming the Mnin stepover. The estimated values suggest displacements of as much as several tens of kilometres. The observed offset along the Tokarnia Fault and theoretical calculations suggest that the strike-slip faults west of the Late Palaeozoic Holy Cross Mountains Fold Belt belong to a large strike-slip fault system. We postulate that the observed significant refraction of the faults forming the anastomosing fault pattern is related also to the interaction of the NW-SE-striking faults formed along the western border of the Teisseyre-Tornquist Zone and the reactivated WNW-ESE-striking faults belonging to the fault systems of the northern margin of the Tethys Ocean.

14

Zastosowanie metody georadarowej do określania położenia swobodnego zwierciadła wód podziemnych w trakcie próbnego pompowania

Gańko M., Mieszkowski R., Gańko A.

Przegląd Geologiczny

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2015

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Vol. 63, nr 10/1

721--726

EN

In this paper were verify the possibilities of use the ground penetrating radar method to defining the range of depression cone during pumping test the first free aquifer. On the experimental area there were: pumping well with observation weels, geotechnical weels and cone penetration tests. This made possible the credible interpretation of the results with GPR investigations. GPR measurements were executed before pumping and after stabilizing the depression. On the echograms there were clearly appeared the free aquifer before and during of the pumping. On the basis of geophisical investigations it was successful to interpret the position of free aquifer and the range of depression cone.

15

Analiza porównawcza wyników badań geofizycznych i geologiczno inżynierskich na potrzeby ustalania modelu geologicznego – na przykładzie poligonu badawczego Kępa Włocławska

Gańko M., Mieszkowski R, Gańko A.

Przegląd Geologiczny

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2015

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Vol. 63, nr 2

121–-130

EN

The paper present the correlation of geophysical method with geological-engineering data. As an experimental testing ground, a terrain with simple soil conditions was selected, located on the W³oc³awek River-islet. This is a large alluvial area on the Vistula River, downstream of the W³oc³awek Dam. In the study, the following geophysical methods were applied: vertical electrical sounding (VES), refraction seismic, ground penetrating radar (GPR) and electrical resistivity tomography (ERT). The evaluation of geological-engineering conditions was executed by using the following methods: drilling, cone penetration test (CPT sounding), measurements of the underground water level and macroscopic and laboratory analyses of soils samples. The results obtained were described and presented in a graphic form.

16

Ocena stanu technicznego wałów przeciwpowodziowych z wykorzystaniem metod geofizycznych i modelowania numerycznego

Popielski P., Chadaj M., Krysiak M., Smoliński B., Kowalczyk S., Mieszkowski R.

Prace Naukowe Politechniki Warszawskiej. Inżynieria Środowiska

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2015

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z. 70

33--55

PL

W pracy przeanalizowano możliwość wykorzystania nowoczesnych metod geofizycznych W ocenie stanu technicznego wałów przeciwpowodziowych. Omówiono pokrótce podstawy teoretyczne pomiarów georadarowych, metody elektrooporowej oraz badań sejsmicznych. Zaprezentowano i przeanalizowano otrzymane wyniki pomiarów. Na podstawie zgromadzonych danych przeprowadzono obliczenia numeryczne rozpatrywanych przekrojów obwałowań w oprogramowaniu Z_Soil.PC, pod kątem zjawisk filtracyjnych i stateczności konstrukcji. We wnioskach końcowych podsumowano wady i zalety poszczególnych metod badawczych. Przedstawiono istniejące ograniczenia i możliwości zastosowania w praktyce.

EN

The paper gives an example of using modern geophysical methods to evaluate the technical condition of levees. The theoretical bases of GPR measurements, electrical resistivity and seismic methods are briefly discussed. Test results for two embankments are presented. Based on the collected data, numerical calculations of the analyzed embankment sections were performed with the Z_SoiI.PC programme. The phenomena of filtration conditions and constructiori stability were examined. In the conclusions section, advantages and disadvantages of each method are given, along with existing limitations and possibilities of practical applicability.

17

Application of electrical resistivity tomography in assessing complex soil conditions

Kowalczyk S., Zawrzykraj P., Mieszkowski R.

Geological Quarterly

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2015

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Vol. 59, No. 2

367--372

EN

Appropriate assessment of spatial variation of soil and hydrogeological conditions is a crucial issue in recognizing foundation soil. The best methods to achieve this goal are those that supply continuous rather than scattered data on soil medium variation. Electrical resistivity was measured with the resistivity cone penetration test (RCPT) and electrical resistance tomography (ERT) with electrodes spaced at 1 and 3 m in order to discriminate peat layers beneath low-resistivity clays. Soil conditions determined by drillings and ERT were not concordant, therefore resistivity modelling of the medium was conducted based on geological units determined by drillings and values of apparent resistivity obtained from RCPT. The strata thickness and electrode spacing is shown to have influence on resistivity imaging in complex soil conditions.

18

Zastosowanie metod geofizycznych do rozpoznania powierzchni stropowej gruntów słabo przepuszczalnych oraz wyznaczenia stref rozluźnienia w korpusie zapory ziemnej

Mieszkowski R., Kowalczyk S., Barański M., Szczepański T.

Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi i Energią PAN

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2014

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nr 86

167--180

PL

Metody geofizyczne wykorzystywane jako badania uzupełniające przy badaniu podłoża umożliwiają ocenę jakościową zmienności warunków gruntowych w strefie przypowierzchniowej. Informacje te są szczególnie istotne w monitoringu podłoża budowli hydrotechnicznych. W artykule przedstawiono badania geofizyczne wykonane w rejonie zapory ziemnej, mające na celu wskazanie miejsc rozluźnienia gruntów w obrębie zapory oraz określenie głębokości stropu gruntów spoistych występujących pod zaporą. Zastosowano metody: tomografii elektrooporowej (ERT), georadarową (GPR), sejsmiki refrakcyjnej, dające dwuwymiarowy obraz zmian fizycznych w ośrodku oraz sejsmikę fal powierzchniowych - Continuous Surface Wave System (CSWS), dzięki której otrzymano profil 1D parametrów sztywności ośrodka w punkcie pomiarowym. Opierając się na rezultatach badan ERT oraz sejsmice refrakcyjnej, odniesione do danych z wierceń, opracowano mapę powierzchni stropowej gruntów słabo przepuszczalnych. Anomalie uzyskane w wyniku interpretacji przeprowadzonych badań geofizycznych pozwoliły na oszacowanie stref rozluźnienia gruntu, które mogą być wywołane procesem sufozji. Zaobserwowane anomalie, na wybranych obszarach, zostały skorelowane z wierceniami oraz sondowaniami statycznymi (CPT), co pozwoliło na zrealizowanie postawionego celu oraz sformułowanie wniosku, że rozkład stref rozluźnienia gruntów oraz zwiększonego przepływu wód gruntowych stwarza zagrożenie dla stateczności korpusu zapory.

EN

Geophysical methods used as a complementary survey in the investigation of substrate allow for a qualitative assessment of the lateral variability of ground conditions in the near surface zone. They can also permit evaluation of the vertical variation of ground conditions. Such information is particularly important in monitoring the substratum of hydrotechnical engineering constructions. This article presents the geophysical surveys carried out in the area of an earth dam in order to identify places of relaxation of soils within the dam, as well as to determine the depth of the roof of cohesive soils occurring under the dam. The following methods were used: Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), seismic refraction (providing a two-dimensional image of the physical changes in the medium), and surface wave seismic - Continuous Surface Wave System (CSWS) used together with Spectral Analysis of Surface Waves (SASW). The last method made it possible to analyze the distribution of the stiffness parameters of the medium at the measuring point. Based on the results of ERT studies and seismic refraction, referring to drilling data, a map of the roof surface of cohesive soils was developed. Anomalies identified in the geophysical studies made it possible to estimate the relaxation zone of the soil that could be caused by a process of suffosion. The observed anomalies in selected areas were correlated with drilling and Cone Penetration Testing (CPT), which allowed the completion of the pursued objective and to draw conclusions for the whole dam.

19

Using Electrical Resistivity Tomography (ERT) as a tool in geotechnical investigation of the substrate of a highway

Maślakowski M., Kowalczyk S., Mieszkowski R., Józefiak K.

Studia Quaternaria

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2014

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Vol. 31, Nr 2

83--89

EN

Geological and geotechnical engineering field tests, like structure drillings and dynamic (DPL, DPSH) or static probing (CPT), are considered for a fundamental source of information about soil and water environments. Since Eurocode 7 has been introduced, it has become more common to use also dilatometers (DMT) or pressure meters (PMT). Results obtained using all the mentioned tests are always of a discrete nature – information is provided in certain points in the field. However, they determine the basis for creating spatial models of geological structure and geotechnical conditions of a substratum. The range and number of investigations conducted (including drilling, probing and laboratory tests) influence precision, in which a geological structure is identified and thus, also affect probability of compatibility between spatial model and real geological conditions of a substratum. In the paper, results of non-invasive electrical resistivity tomography (ERT) method are presented, comprising 2-dimensional image of a soil medium resistance. Electrical resistance is a parameter that reflects diversification of a soil medium, considering its lithological aspect. In addition, when combined with drilling results, it can be used to accurate determination of boundaries between soil layers. Carrying out of ERT tests in the field during expressway construction contributed to identification of weak, low-strength soils like organic soils (peat, aggradated mud) and of soft consistency cohesive soils. These kinds of soil are the main cause for unacceptable deformations appearing in the new road engineering structure.

20

The role of geophysical ERT method to evaluate the leakproofness of diapragm wall of deep foundation trenches on the example of the construction of retail and office complex in Lublin, Poland

Pacanowski G., Czarniak P., Bąkowska A., Mieszkowski R, Welc F

Studia Quaternaria

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2014

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Vol. 31, Nr 2

91--99

EN

This paper addresses the problem of assessing the leakproofness of the bottom of a deep foundation trench, secured by cavity wall, using geophysical methods of electrical resistivity tomography. The study was conducted on a large construction project in Lublin, in a place where there are complicated soil-water conditions: the groundwater level is above the proposed depth of foundation trench, the subsoil is heterogeneous, and there are karsted and weathered carbonate sediments with confined aquifer below the bottom of the trench. A hydraulic fracture occurred at the bottom of the trench during the engineering works, which caused the water flow into the trench. In order to recognize the soil-water conditions the first stage of geophysical measurements of electrical resistivity tomography (ERT) was made. The applied methodology allowed to determine the extent of the hydraulic fracture zone within the bottom of foundation trench. In order to assess the leakproofness of Diaphragm Wall the geophysical ERT measurements were repeated (stage 2) A clear reduction in the value of the electrical resistivity of soils in the area of hydraulic fracture was caused by clay injection. The results of ERT measurements are discussed and graphically presented.