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Recognition of the flysch substrate using the electrical resistivity tomography (ERT) method to assess the effectiveness of the injection process

Ćwiklik Michał, Pasierb Bernadetta, Porzucek Slawomir

Geology, Geophysics and Environment

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2023

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Vol. 49, no. 2

197--202

EN

During the construction of a section of the S-7 Lubień – Rabka-Zdrój dual expressway, located in the area of the Carpathian flysch (Carpathian Flysch Belt, South Poland), damage to the embankment was observed, as well as cracks and depressions in the new pavement. An analysis of the geological and engineering conditions in the area of the road section under construction showed the existence of a complex tectonic structure of the flysch formations, a shallow groundwater table, and numerous landslides. In order to stabilize the road substrate, it was decided to carry out injections, and the locations of these injections were initially geotechnically tested. However, due to the high variability of the geological structure, the target method employed was electrical resistivity tomography (ERT), which performed the survey in two stages. In Stage I, the geoelectrical/geochemical structure of the near-surface zone was identified, and the probable causes of road damage were indicated. This stage was completed by performing the stabilization and sealing process of the ground with an injection mixture. In Stage II, studies were carried out to evaluate the effectiveness of the injection process. The ERT method effectively identified the shallow geological structure and, in particular, delineated the zone of strong fractures in the flysch and areas associated with faults. Using the electrical resistivity tomography method, it was also possible to determine the injection mixture’s approximate penetration depth and the loosening zone’s degree of filling.

2

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.

3

Numerical evaluation of 2D electrical resistivity tomography for subsoil investigations

Pasierb B.

Czasopismo Techniczne. Środowisko

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2015

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Y. 112, iss. 2-Ś

101--112

EN

The use of numerical methods for the design and analysis of hydraulic engineering structures requires an accurate determination of the model of subsoil structure. The article presents one of the geophysical methods – electrical resistivity tomography (ERT), which allows for precise, spatially instant recognition of the substrate and the phenomena occurring within it. The methodology, the applied algorithm for numerical calculation, and data processing procedure are discussed. This article also introduces a method of inversion which relies on finding the actual model and presents examples of its application.

PL

Zastosowanie metod numerycznych do projektowania oraz analizy konstrukcji hydrotechnicznych wymaga określenia modelu budowy podłoża. W artykule zaprezentowano metodę tomografii elektrooporowej ERT stosowaną dzięki ciągłemu, przestrzennemu rozpoznaniu podłoża i zjawisk w nim zachodzących, m.in.: w geotechnice, hydrotechnice, a także w zagadnieniach obejmujących projektowanie konstrukcji inżynierskich. Przedstawiono metodologię, stosowane algorytmy do obliczeń numerycznych oraz procedury przetwarzania danych. Przybliżono metodę inwersji polegającą na znalezieniu modelu rzeczywistego ośrodka oraz zaprezentowano przykłady jej stosowania.

4

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.

5

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.

6

Application of Electrical Resistivity Tomography (ERT)in the investigation of quaternary landslide zones, based on the selected regions of Płock slope

Kaczmarek Ł., Mieszkowski R., Kołpaczyński M, Pacanowski G.

Studia Quaternaria

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2014

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Vol. 31, Nr 2

101--107

EN

The article shows the results of geophysical surveys performed by using Electrical Resistivity Tomography (ERT) method on selected ragion of Płock slope of a Tumski hill near Basilica of Assumption of the Blessed Virgin Mary in Płock and in Maszewo by the Vistula River a few kilometers north of Płock. The above-mentioned sections were selected due to landslide phenomena observed there. Geophysical surveys were conducted in order to verify the state of the distribution of electrical resistivity in the sectors where mass movement was identified. The electrofusion crosssection near Cathedral Basilica shows clays and sands. Also in ERT prospection a zone of loose soils with high resistance is clearly visible. The results of the ERT method from Maszewo, indicates historical land surface of a landslide and that the slope in Maszewo consists of cohesive deposits. In order to describe these particular issues, geological cross-sections and safety factor obtained by calculation are presented for the analyzed parts of the slope. The safety factor shows that probability of landslide activity near Cathedral Basilica is very unlikely and in Maszewo is very high.

7

Wykorzystanie przypowierzchniowych badań geofizycznych w rozpoznaniu budowy geologicznej na przykładzie stref osuwiskowych w Karpatach

Ostrowski S., Rybak-Ostrowska B., Lasocki M.

Przegląd Geologiczny

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2013

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Vol. 61, nr 1

67–-73

EN

The paper presents three examples of application of geophysical surveys carried out by the PBG Ltd. for the recognition of internal structure, geological background and mechanical properties of near- -surface rock medium at major landslides in the Polish Outer Carpathians. Geophysical data were used for developing an accurate geological model of the landslides. Geological features that cannot be detected by other means, e.g. faults in bedrock, and exact location and shape of the shear plane were delineated in two-dimensional mode on the sections.

8

2D Electrical Resistivity Tomography interpretation ambiguity - example of field studies supported with analogue and numerical modelling

Bania G., Ćwiklik M.

Geology, Geophysics and Environment

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2013

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Vol. 39, no. 4

331--339

EN

Single Electrical Resistivity Tomography (ERT) survey was carried out in the Manor and Park Complex in Nowa Huta (Krakow Branice, Poland). It was applied at a small distance and parallel to the longer wall of a monumental building containing an empty 3 m deep basement. Analogue modelling was performed in order to recreate the field study at the proper scale. The laboratory set-up consisted of a water tank where electrodes were mounted to the particular plate, which rested on water surface. The basement model was made out of a non-conducting material. The default and robust inversions were tested and these variants were also considered with the use of numerical modelling. Laboratory experiments have confirmed that zones visible in the interpreted field section are caused by the influence of the building cellar located next to the survey line. Zones of this kind are additionally disturbed by the local geological structure. The experiment has pointed out, among others, that as the distance between the survey line and the underground body increases, the inversion results are still burdened by an object influence. Thus, similar situations can be verified with the use of analogue modelling presented in this paper or 3D numerical one.

9

Zastosowanie metody georadarowej i tomografii elektrooporowej do obserwacji położenia swobodnego zwierciadła wód pierwszego poziomu wodonośnego

Gańko M., Mieszkowski R., Gańko A.

Biuletyn Państwowego Instytutu Geologicznego

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2013

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nr 456 Hydrogeologia z. 14/1

161--166

PL

W artykule zaprezentowano ocenę możliwości zastosowania metody georadarowej i tomografii elektrooporowej w rozpoznaniu hydrogeologicznym płytkich wód podziemnych. Podjęto próbę wydzielania warstw geologicznych, wyznaczania głębokości do zwierciadła wód podziemnych, oraz określono czynniki mające wpływ na dokładność rozpoznania.

EN

The paper presents the appraisal of Ground-Penetrating Radar (GPR) tests and Electrical Resistivity Tomography (ERT) tests used in the hydrogeological exploration of shallow groundwater level. An attempt was made to identify geological layers and determine the distance downward to the groundwater level.

10

Saltwater monitoring with long-electrode electrical resistivity tomography

Voß T., Ronczka M., Gunther T.

Biuletyn Państwowego Instytutu Geologicznego

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2013

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nr 456 Hydrogeologia z. 14/2

621--626

EN

Since 2011 the German well logging company Bohrlochmessung – Storkow GmbH and the German Leibniz Institute for Applied Geophysics are engaged in the joint research project ‘SAMOLEG – Saltwater monitoring with long electrode geoelectrics’ (electrical resistivity tomography – ERT), with a grant of the German Federal Ministry of Education and Research. The basic concept of SAMOLEG is to use the existing networks of old steel-cased groundwater measuring wells as current injection and voltage electrodes for electrical resistivity tomography measurements in order to obtain deeper access to salt water bearing aquifers than with conventional surface ERT. Permanent wiring of several old wells would give the opportunity to conduct cost-efficient ERT measurements for saltwater monitoring with a high temporal sampling on sites that are threatened by saltwater rise due to anthropogenic (e.g. natural gas /CO2-storage, water production from wells) or natural causes (e.g. decreasing precipitation due to climate change). First model tank and numerical modelling experiments reveal different sensitivities of ‘equal-length’ and ‘unequal-length’ combinations of wells to rising or laterally inflowing saltwater. Field measurements on a test site in Eastern Brandenburg with known groundwater salinization demonstrate the monitoring potential of the SAMOLEG concept.

PL

Od 2011 roku niemieckie przedsiębiorstwo geofizyki otworowej Blm–storkowgmbh wspólnie z Instytutem Leibniza ds. Geofizyki Stosowanej są zaangażowane w projekt badawczy pt. „SAMOLEG – Monitorowanie zasolenia wód podziemnych za pomocą elektrooporowej metody długich elektrod” (tomografia elektrooporowa) – grant Niemieckiego Federalnego Ministerstwa Edukacjii Badań Naukowych. Zasadniczą ideą projektu SAMOLEG jest wykorzystanie istniejącej sieci starych stalowych studni i piezometrów jako elektrod prądowych i pomiarowych w technice tomografii elektrooporowej, w celu dostępu do głębszych zasolonych poziomów wodonośnych, niż mogłoby to mieć miejsce, bazując na konwencjonalnych powierzchniowych metodach elektrooporowych. Trwałe okablowanie kilku studni w wybranej sieci badawczej dałoby możliwość przeprowadzania częstego niskonakładowego monitoringu zasolenia wód w miejscach, które z przyczyn antropogenicznych (np. Magazynowanie gazu lub CO2, zintensyfikowane ujmowanie wód podziemnych) oraz naturalnych (np. Niewielkie opady atmosferycznewywołane zmianami klimatycznymi) zagrożone są podniesieniem się poziomu wód zasolonych. Pierwsze badania laboratoryjne oraz modelowanie numeryczne ujawniły zmienne czułości kombinacji elektrod o równej i różnej długości względem wznosu lub bocznego dopływu wód, natomiast pomiary terenowe we wschodniej Brandenburgii, na polu testowym o znanym zasoleniu wód podziemnych, potwierdziły zakładany potencjał monitoringowy koncepcji SAMOLEG.

11

Obraz fizyczny zwierciadła wód pierwszego poziomu wodonośnego w świetle badań metodą tomografii elektrooporowej (ERT)

Gańko M., Mieszkowski R., Gańko A., Tuchołka P.

Biuletyn Państwowego Instytutu Geologicznego

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2013

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nr 456 Hydrogeologia z. 14/1

167--172

PL

W artykule przedstawiono i omówiono wyniki rozpoznania pierwszego poziomu wodonośnego za pomocą metody tomografii elektrooporowej (ERT). Wybrano trzy poligony badawcze w obrębie Warszawy, o różnej budowie geologicznej i odmiennych warunkach hydrogeologicznych. Jeden poligon znajduje się w obrębie wysoczyzny polodowcowej na terenie Warszawy („Pole Mokotowskie”), a dwa pozostałe są położone w obrębie doliny rzeki Wisły („Józefów” i „Tarchomin”). Poligony umiejscowione w obrębie doliny rzeki charakteryzują się m.in. swobodnym poziomem zwierciadła wody, natomiast w obrębie poligonu na wysoczyźnie polodowcowej występuje poziom wodonośny pod ciśnieniem. Rezultaty wykonanych badań dowodzą, że poziom wód podziemnych wyraźnie zaznacza się w obrazie uzyskanym metodą ERT, ale nie zawsze daje precyzyjne wyniki. Dokładność jego wyznaczenia zależy od uziarnienia gruntów, ich kontrastu opornościowego, wilgotności, metody profilowania elektrycznego oraz od ukształtowania stropu osadów niskooporowych (Warszawa – iły plioceńskie).

EN

The paper presents the results and interpretation of Electrical Resistivity Tomography (ERT) study of the first aquifer. The study was carried out in the Warsaw region on three selected test fields with different geological structure and hydrogeological conditions: two in the Wisla River valley (“Józefów” and “Tarchomin”) and one in a postglacial upland in Warsaw (“Pole Mokotowskie”). The river valley aquifers are unconfined, whereas in the upland, the first aquifer is confined and under pressure. The results clearly show the presence of aquifers on the ERT image, but the positioning of the water level is not always precise. The precision depends on granulometry of sediments, resistivity contrasts, chosen method of resistivity measurement and morphology of low-resistivity sediments (e.g. Pliocene clays in the Warsaw area).

12

Techniki pomiarowe metody elektrooporowej

Pasierb B.

Czasopismo Techniczne. Środowisko

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2012

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R. 109, z. 2-Ś

191--199

PL

W artykule przedstawiono techniki pomiarowe geofizycznej metody elektrooporowej: sondowania elektrooporowe, profilowania elektrooporowe EP i tomografię elektrooporową ERT. Omówiono ich podstawowe założenia metodyczne, zalety oraz ograniczenia. Szerzej przedstawiono jeden z najbardziej popularnych wariantów tej metody – tomografię elektrooporową ERT.

EN

The article presents the basic techniques of measuring geophysical resistivity methods: Vertical Electrical Sounding VES, Electrical Profiling EP and Electrical Resistivity Tomography ERT. Discussed the basic methodological assumptions, advantages and limitations. Electrical Resistivity Tomography ERT – one of the most popular variants of this method was presented more widely.

13

Metoda tomografii elektrooporowej w rozpoznawaniu geologicznym podłoża i obiektów antropogenicznych

Pasierb B.

Czasopismo Techniczne. Środowisko

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2012

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R. 109, z. 2-Ś

201--209

PL

W artykule przedstawiono tomografię elektrooporową jako metodę umożliwiającą rozpoznanie budowy geologicznej podłoża. Metodę tomografii elektrooporowej wykorzystano również w celu wykrycia podziemnych obiektów antropogenicznych na terenie Brzozówki w gminie Zielonki i miejscowości Zabierzów. Łącznie wykonano 6 profili, na podstawie których omówiono możliwości zastosowania tomografii elektrooporowej w płytkiej prospekcji, jak również jej możliwości detekcji i lokalizacji obiektów antropogenicznych.

EN

The article presents a method of electrical resisitivity tomography which allows to identify the geological structure of the basement. Resistivity tomography was also used to detection of anthropogenic objects in Brzozówka and Zabierzów areas. A total of six profiles were done, on the basis of which it also describes applications of the electrical resistivity tomography for the near surface prospecting as well as its ability to detect and localize antropogenic objects.