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1

Study on groundwater table distribution of loess tableland in the South Jingyang tableland, Northwest China

Wu Jiaqi, Dai Fuchu, Liu Pan, Huang Zhiquan, Wu Daixuan

Acta Geophysica

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2024

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Vol. 72, no. 1

257–-272

EN

The South Jingyang tableland, located in Shaanxi Province, China, is composed of loess deposits. Agricultural irrigation in this area has caused the continuous rise of the groundwater table, which triggered a series of loess landslides. Although extensive research has been conducted on the effect of rising groundwater tables on induced loess landslides, less is known about the groundwater table distribution. This study jointly investigated the distribution of the groundwater table in the South Jingyang tableland using boreholes, electrical resistivity tomography (ERT), and laboratory tests. A qualitative analysis between the apparent resistivity and the water content was estimated at different depths, using the borehole data and ERT inversion data. A quantitative relationship between the resistivity and the water content was established in the laboratory tests. A combination of the qualitative analysis of the inversion results and the quantitative relationship was used to determine the distribution of the groundwater table. The groundwater table is present at the depth where the water content of the loess is 30% (liquid limit of loess) and the resistivity is 28.35 Q m. The groundwater table elevation in the southern study area is higher than that of the northern study area and decreases in a stepwise gradient from south to north. This study not only identified the distribution of the groundwater table in the South Jingyang tableland, but also makes up for the limitation and inaccuracy in determining groundwater tables by relying solely on the borehole information or inversion results of ERT. The ascertained distribution characteristics of the groundwater table provides a basis for the analysis of the formation mechanism of landslides.

2

Near-surface geophysical characterization of gully erosion hazard-prone area in Calabar, southern Nigeria

Ebong Ebong Dickson, Urang Job Gideon, Melouah Oualid, Ugi Anthony Ukpongnukpon, Sule Andebutop

Acta Geophysica

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2024

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Vol. 72, no. 1

85-–96

EN

The electrical resistivity, i.e. electrical resistivity tomography (ERT) and direct current-resistivity sounding (DC-ERS), and ground penetrating radar (GPR) methods were deployed to assess a gully erosion site in Bacoco area of Calabar, Nigeria. The study aims to assess the mechanism and dynamics of the gully erosion conditions in the area based on shallow lithostrati-graphic evaluations. The results revealed good contrast in the operative properties (i.e. electrical resistivity and dielectric permittivity) between competent and weak zones along the profiles close to the gully head. The joint interpretations provided reliable shallow subsurface models and lithologies that consist predominantly of lateritic top cover and sands. However, the ERT model delineates the contrast between lithologies and demarcates the weak zones from the relatively competent zones, in contrast to the responses generated by the GPR technique. This joint interpretation approach minimizes the uncertainty due to the non-uniqueness problems common to the geophysical technique. Also, the geophysical interpretations were constrained using lithologic information from the gully walls and one-dimensional (1-D) DC-ERS inverted model to provide additional validity. Our findings suggest the influence of structural control on gully formation and demonstrate its contribution to the complex interactions with other drivers, such as seepages through porous media and high-energy runoff due to intense rainfall. The rapid, non-invasive and environmentally friendly characteristics of ERT and GPR techniques favour their applicability in assessing shallow subsurface environmental problems.

3

An integrated approach for landslide hazard assessment: A case study of the Middle Dnieper Basin, Ukraine

Ivanik Olena, Fonseca Joana, Shabatura Oleksandr, Khomenko Ruslan, Hadiatska Kateryna, Kravchenko Dmytro

Journal of Water and Land Development

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2022

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no. 52

81--86

EN

Ukraine is characterised by active natural hazards processes within different structural, tectonic and landscape zones. In Middle Dnieper basin region mass movement processes have great impact on people’s livelihoods and infrastructure. These processes occur on the slopes with different geological structure. The determining causes include lithologic and stratigraphic conditions, hydrogeological regime, structural and textural peculiarities of rocks and the geomorphology of the slopes. Landslide inventory database has been developed based on long-term observations of more than 400 landslides and landslide-prone areas. This paper takes efforts forward by combining different geological and geophysical methods to advance the current understanding of landslide phenomena and contributing towards a better informed assessment of landslide hazard and risk. The developed methodology is implemented in a test sites of Kyiv region, covering an area of 18.3 km2 situated in the Middle Dnieper basin. Electrical Resistivity Tomography, Self-Potential and Infrared Thermography techniques were employed to investigate the lithostratigraphic sequences, the geometry of landslide body and potential mass movement. The results presented here confirm the potential of using an integrated approach that combines different field data to better plan mitigation activities and measures for the effective land management. This study will be useful in increasing the safety aspects of the infrastructures and lives and also for planning of research and developmental activities.

4

Subsurface imaging of fluvial deposits of the Wisła River valley in Kraków (southern Poland) by 2D ERT survey

Bania Grzegorz, Woźniak Tomasz

Geological Quarterly

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2022

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Vol. 66, No. 3

art. no. 23

EN

We describe the application of 2D ERT (electrical resistivity tomography) surveys to investigate the spatial complexity of fluvial deposits of the Wisła River valley in the eastern part of Kraków (southern Poland). All ERT survey lines were completed within the industrially influenced floodplain of the Wisła River at two research sites. Due to the transformation of the natural state of the environment through many years of industrial activity of the ArcelorMittal Kraków plant, some of the geomorphological elements analysed have been irretrievably transformed and hidden by anthropogenic accumulations such as waste landfills and engineering structures. Hence, many years of soil contamination have changed the primary resistivity characteristics of the subsurface. For this purpose, the measurement array applied combines standard arrays, i.e., Wenner-Schlumberger and Dipole-Dipole, which gave improved results (higher resolution) in comparison to the standard single array. The data interpretation method was supported by the calculation and visualization of the vertical and horizontal gradients of the interpreted resistivity within the resistivity sections. This approach allowed accurate determination of resistivity boundaries on the ERT resistivity sections and thus helped lithological interpretation of the fluvial deposits in the research area. The resistivity of water in a channel located within one of the analysed areas has impacted some of the research results. Furthermore, 2D ERT forward modeling was implemented to generate synthetic datasets. The synthetic data allowed investigation of the influence of groundwater contamination on the resistivity distribution within superficial layers, and also tested the ability of the 2D ERT model to recognize the detailed spatial distribution of palaeomeander (meander scar) infills. All methods have provided new information on the industrially influenced floodplain of the Wisła River in Kraków.

5

Practical aspects of field work carried out by Electrical Resistivity Tomography

Pacanowski Grzegorz, Maślakowski Maciej, Lejzerowicz Anna

Archives of Civil Engineering

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2022

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Vol. 68, nr 4

331--346

EN

The following article collects and describes several practical problems that can be encountered when performing geophysical field measurements using the electrical resistivity tomography (ERT) method. The methodology of work carried out with the Terrameter LS apparatus of the Swedish company ABEM (currently the company has changed its name to GUIDELINE GEO) was presented and discussed. The attention was paid to interesting solutions that increase the efficiency of works, especially in works related to linear investments. Errors that may appear during the use of the roll-along method are indicated, in particular, those appearing in measurements where too long measurement sections are transferred, as well as problems resulting from high electrode earthing, nonlinear profile traces and variable morphology. It describes how the use of different measurement systems affects the depth of prospecting, and which systems cope well in the area with disturbances. The article also emphasizes that the work should be properly planned before starting field research.

PL

W niniejszym artykule zebrano i opisano kilka praktycznych problemów, z którymi można się spotkać w trakcie wykonywania geofizycznych pomiarów polowych, stosując metodę tomografii elektrooporowej (ERT). Przedstawiono i omówiono metodykę prac wykonywanych aparaturą Terrameter LS szwedzkiej firmy ABEM (obecnie firma zmieniła nazwę na GUIDELINE GEO). Zwrócono uwagę na ciekawe rozwiązania, które zwiększają efektywność prac, szczególnie w pracach związanych inwestycjami liniowymi. Wskazano błędy jakie mogą pojawić się podczas stosowania metody roll-along, w szczególności pojawiające się w pomiarach gdzie przenoszone są zbyt długie sekcje pomiarowe, a także problemy wynikające z wysokich uziomów elektrod. Opisano jak stosowanie różnych układów pomiarowych wpływa na głębokość prospekcji, a także które układy radzą sobie dobrze w obszarze z zakłóceniami. W artykule zwrócono uwagę na to by w odpowiedni sposób planować prace przed przystąpieniem do badań terenowych.

6

Detailed LNAPL plume mapping using electrical resistivity tomography inside an industrial building

Meng Jian, Dong Yanhui, Xia Teng, Ma Xinmin, Gao Cuiling, Mao Deqiang

Acta Geophysica

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2022

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Vol. 70, no 4

1651--1663

EN

Detailed characterization of light non-aqueous phase liquid contaminant plume is essential for mapping remediation scope effectively. Electrical resistivity tomography is increasingly popular for delineating the geometry of subsurface contamination. In this study, the low resolution and limited penetration depth drawbacks from traditional survey arrays were resolved with optimized arrays generated using ‘Compare R’ method. Numerical example first proved its efficiency in locating contaminated areas under restricted survey space. The presence of ethylbenzene inside a manufacturing building has shown high resistive anomaly, and it has already leaked into deep locations from resistivity results. However, the transport of ethylbenzene was limited due to surrounding low permeable clay layer. The boundaries of the contaminant plume were further quantified using interpolated 3D resistivity results, which help to refine the remediation scope. The reconstructed scope was only 1/3 of the one from traditional borehole data interpolation, resulting in a more precise remediation cost estimate. In the end, we conclude the advantage of enhanced resolution and refined cost of remediation strategy by applying optimized array in contaminated site survey.

7

Application of electrical resistivity tomography for imaging seawater intrusion in a coastal aquifer

Niculescu Bogdan Mihai, Andrei Gina

Acta Geophysica

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2021

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Vol. 69, no. 2

613--630

EN

Following previous geoelectrical researches initiated in 2009 for the delineation and characterization of seawater intrusion in a freshwater aquifer of Sarmatian (late Middle Miocene) age, a subsurface imaging survey via 2-D electrical resistivity tomography (ERT) was conducted in 2019 on the outskirts of Vama Veche resort—Romanian Black Sea southern coast. The survey was organized in the framework of a feld camp sponsored by the Foundation of the Society of Exploration Geophysicists (SEG)–Tulsa, OK, USA, with participation of teams from the University of Bucharest—Department of Geophysics and the Geological Institute of Romania. A number of eight ERT profles with N–S, W–E, NNE–SSW, and WNW–ESE orientation and 155–315 m length were imaged with a SuperSting R8/IP instrument (Advanced Geosciences Inc.), using deployments of 32–64 electrodes at 5 m spacing, in Wenner, Schlumberger, and dipole–dipole array confgurations. The processing and interpretation of high-resolution ERT data indicated that the seawater intrusion, evidenced as very low resistivity (5–10 Ω m) anomalous zones starting at approximately 45–49 m depth, has advanced at least 500 m inland. The survey results also allowed the identifcation of a system of fractures or faults with an approximate NW–SE/WNW–ESE and, possibly, N–S orientation, that might have provided potential pathways for saline water intrusion.

8

Electrical resistivity tomography for geo-engineering investigation of subsurface defects: a case study of Etioro-Akoko highway, Ondo State, southwestern Nigeria

Akingboye Adedibu Sunny, Osazuwa Isaac Babatunde, Mohammed Muraina Zaid

Studia Quaternaria

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2020

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Vol. 37, Nr 2

101--107

EN

The durability of roads is dependent on the proper screening of the variations in subsurface geological characteristics and conditions through geo-engineering investigations and good construction practices. In this study, electrical resistivity tomography (ERT) technique was used to investigate the subsurface defects and potential failures along the substrate of Etioro-Akoko highway, Ondo State, southwestern Nigeria. Results of the inverse model resistivity sections generated for the two investigated traverses showed four distinct subsurface layers. The shallow clayey topsoil, weathered layer, and partially weathered/fractured bedrock have resistivity values ranging from 4–150 ohm-m, 10–325 ohm-m, and 205–800 ohm-m, with thickness values of 0–2 m, 0.5–12.5 m, and less than few meters to > 24 m, respectively. The fresh bedrock is characterised by resistivity generally in excess of 1000 ohm-m. The bedrock mirrored gently to rapidly oscillating bedrock troughs and relatively inclined deep penetrating multiple fractures: F1–F'1, F2–F'2 and F3–F'3, with floater in-between the first two fractures. These delineated subsurface characteristic features were envisaged as potential threats to the pavement of the highway. Pavement failures in the area could be attributed to the incompetent clayey sub-base/substrate materials and the imposed stresses on the low load-bearing fractured bedrock and deep weathered troughs by heavy traffics. Anticipatory construction designs that included the use of competent sub-base materials and bridges for the failed segments and fractured zones along the highway, respectively, were recommended.

9

The contribution of geophysics to archaeology: a case study of an ancient canal of the Oc Eo culture in the Mekong Delta, Vietnam

Le Ngoc Thanh, Nguyen Quang Dung, Nguyen Quang Bac, Nguyen Quang Mien, Nguyen Dan Vu, Duong Ba Man, Nguyen Dinh Chau

Geology, Geophysics and Environment

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2019

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Vol. 45, no. 1

45--56

EN

Generally, underground ancient canals are infilled with alluvial materials, with the canal bed and substrate often having different resistivity values. This study aimed to determine the location and morphology of Malleret’s ancient canal 16 located to the southeast of the Ba The mountain, Mekong Delta, Vietnam by means of geophysical techniques. Two geophysical methods were used: electromagnetic profile and electric resisitivity tomography. A geoelectric structure 70 m long with 70–95 mS/m of apparent conductivity was found. On the electrical resistivity tomography section, a resistivity zone of 10–20 Ω∙m, 1–4 m deep, 70 m wide corresponds to the mentioned above geoelectric structure, which is in an asymmetric U-shape extending toward the southeastern bank of canal 16. Hand-augering confirmed that the canal bed is fully incised into Holocene sediments as a substrate which stretches down to the Pleistocene. The sediments are composed of loams mixed with plant remains with a resistivity ρ ~ 10–15 Ω∙m. Both of the canal banks at a depth of 5 m are made up of Holocene sedi-ments (ρ ~ 4–10 Ω∙m). The 14C measurements determined the age of the organic matter in the canal as being equal to 1210 ±85 BP, suggesting canal 16 ceased being operational at that time. The precise positioning of canal 16 on the ground surface, as well as identifying the morphology of the canal bed, were corroborated by geophysical techniques. The obtained results are of considerable value to archaeologists.

10

Geophysical and geotechnical approach to a landslide stability assessment: a case study

Pasierb Bernadetta, Grodecki Michał, Gwóźdź Rafał

Acta Geophysica

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2019

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Vol. 67, no. 6

1823--1834

EN

Landslides are complex phenomena, and the main factors that have a significant impact on their behavior are changes in slope inclination geometry and changes in water conditions. The main purpose of this work was to evaluate current conditions of the landslide in Brzozówka, near Cracow (Poland), and analyzing how different saturations of soil influence the stability of the landslide. The combination of geophysical and geotechnical research, such as electrical resistivity tomography (ERT), cone penetration testing, drilling and laboratory tests as well as a comprehensive analysis of their results, provided reliable information on the geological structure and geotechnical parameters of the landslide. The results were used in numerical simulations of the landslide stability, in which a two-phase model (soil and water) was assumed that included the effective soil strength parameters and the transient flow conditions as well as a partial saturation zone. The sliding surface obtained from the numerical modeling was almost flat, which was confirmed by the ERT method. It was proved that the landslide occurred when the saturation of the upper part of the slope exceeded 0.8. Obtained results are useful for engineering practice.

11

Electrical resistivity tomography (ERT) and sedimentological analysis applied to investigation of Upper Jurassic limestones from the Krzeszowice Graben (Kraków Upland, southern Poland)

Woźniak T., Bania G., Mościcki W. J., Ćwiklik M.

Geological Quarterly

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2018

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Vol. 62, No. 2

287--302

EN

This paper highlights the application of shallow non-invasive geophysics (electrical resistivity tomography) supported by sedimentological analysis applied to the investigation, description and interpretation of Upper Jurassic limestones exposed in the abandoned quarry near the village of Tomaszowice (Kraków Upland, southern Poland). Within this site, on the northern margin of the Krzeszowice Graben, a facies diversity of Upper Jurassic limestones can be observed. Field exposures were analysed to broadly characterize these Upper Jurassic limestones in terms of facies and microfacies development. Three facies types, including pelitic limestones, bedded limestones and carbonate gravity-flow deposits, composed of numerous microfacies, have been distinguished. ERT study using a dipole-dipole array has been carried out, along 5 parallel 110 m long profiles and along a perpendicular 110 m long profile, north of the Tomaszowice Quarry wall. The use of ERT in combination with the geological data allowed characterization and description of the geology at the research site as well as the determination of the lithological composition and internal architecture of the subsurface. Furthermore, the ERT interpretation results indicated the presence of a series of a secondary faults closely linked with the Krzeszowice Graben. The distribution of the gravity-flow deposits reflects the fault zone pattern of the graben and Late Jurassic fault activity.

12

Case study of electrical resistivity tomography measurements used in landslides investigation, Southern Poland

Mita M., Glazer M., Kaczmarzyk R., Dąbrowski M., Mita K.

Contemporary Trends in Geoscience

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2018

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Vol. 7, iss. 1

110--126

EN

Mass movements are an ever present threat to building construction, water management, vegetation formation and biodiversity. This paper presents an approach to landslides research based on non-invasive geoelectrical method - Electrical Resistivity Tomography (ERT). Mapping and displacement monitoring of unstable slopes is crucial for the hazards prevention and assessment. The ERT technique is an effective tool to obtain structural differentiation of geological medium through interpretation of 2D electrical resistivity models. The main advantage of the method is a wide range of applicability what makes its useful during field works on a landslide. It is commonly used for measurements of slope instability, determination of shear surface, landslide susceptibility, depth of bedrock, slip plane geometry. The aim of the work is to identify the geological structures underneath three selected landslides in south Poland: in Racibórz, Milówka and Porąbka. Attempts have been focused on determination of the usefulness of the proposed ERT methodology for evaluation of possible further development of mass movements. On two investigation sites two different arrays have been used: Wenner-Schlumberger and dipole-dipole which allowed to prepare combined data set and resistivity models based on them. Forward modelling of synthetic models based on a priori information allowed to understand anomalies present on resistivity models. Applied approach ensured quality increase of final interpretation of resistivity models.

13

Assessment of contamination in Namson Landfill, Hanoi, Vietnam by hydrogeophysical methods

Giang N. V., Vu N. T., Duan N. B.

Archives of Mining Sciences

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2018

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Vol. 63, no. 2

397--416

EN

The main objective of this study was to assess the environmental impact of the subsurface geological structure in Nam Son landfill by hydrogeophysical method. The Electrical Resistivity Tomography (ERT), Self-Potential (SP) and Very Low Frequency (VLF) method was used for geological structure investigation. Three profiles (total 900 m long) of two-dimensional ERT, VLF density sections and 180 SP data points scattered within the study area near the disposal site were implemented. Surface water and groundwater samples were collected from 10 sites in the area for hydrochemical analysis. Interpretations of geophysical data show a low resistivity zone (<15 Ω m), which appears to be a fully saturated zone with leachate from an open dumpsite. There is a good correlation between the geophysical investigations and the results of hydrochemical analysis.

PL

Podstawowym celem pracy było określenie stopnia oddziaływania na środowisko w podpowierzchniowych warstwach geologicznych na obszarze składowiska odpadów Nam Son przy wykorzystaniu metod hydro-geofizycznych. W badaniach budowy geologicznej terenu wykorzystano metodę obrazowania elektrooporowego (Electrical Resistivity Tomography – ERT), metodę potencjałów własnych (Self-Potential – SP) oraz badania elektromagnetyczne bardzo niskich częstotliwości (Very Low Frequency – VLF). Wytypowano trzy profile (o całkowitej długości 900 m) do dwuwymiarowego obrazowanie ERT oraz siatki gęstości do badania elektromagnetycznego VLF oraz 180 rozproszonych punktów do badań metodą potencjałów własnych na badanym terenie. Próbki wód powierzchniowych i gruntowych do analizy chemicznej pobrano z 10 lokalizacji na terenie składowiska. Interpretacja danych geofizycznych wykazała istnienie strefy charakteryzującej się niskimi oporami (<15 Ω), w pełni nasyconej odpadami ciekłymi wypłukiwanymi z otwartego składowiska. Stwierdzono wysoki poziom korelacji pomiędzy rezultatami badań geofizycznych a wynikami analiz chemicznych.

14

Compiling and verifying 3D models of 2D induced polarization and resistivity data by geostatistical methods

Mostafaei K., Ramazi H.

Acta Geophysica

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2018

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Vol. 66, no. 5

959--971

EN

A 3D model of collected time-domain induced polarization (IP) and electrical resistivity tomography (ERT) data is compiled by geostatistical methods as well as studying spatial correlation among the database. Mesgaran copper deposit, located in Birjand eastern Iran, was chosen to compile and verify the model, leading to five parallel surveyed IP and ERT profiles with dipole–dipole arrays. The collected data were inverted, and then 2D models of IP and ER were prepared; also 3D inversion was done. Afterward, the 3D model has been built by geostatistical methods. Correspondingly, the anomalies threshold was detected by fractal methods and the estimation variance and Kriging efficiency were calculated to validate the modeling. The mineralization zones were determined according to the classified anomalies and those with the lowest error. Results indicated a high correlation between anomalies identified from the model and mineralization. The results made it possible to construct 3D models from surveyed 2D data with acceptable error level.

15

Zastosowanie badań konduktometrycznych z użyciem inwersji 1D, jako narzędzia do kartowania przestrzennego przypowierzchniowych warstw geologicznych

Czarniak P., Pacanowski G., Sobótka P.

Przegląd Geologiczny

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2017

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Vol. 65, nr 10/2

803--810

EN

This article presents the results obtained from geophysical measurements as a supplement to and refinement of geological information obtained from engineering geological studies for the newly constructed highways. The research was conducted using two geophysical methods: Ground Conductivity Meters (GCM) and Electrical Resistivity Tomography (ERT). The above measurements were made on three research fields located along the planned express road S-19 (Kraśnik-Janów Lubelski section). These areas were selected due to the large amount of available archival data and varied geological conditions. The publication focuses primarily on the presentation of the results obtained using the very fast and extremely efficient GCM method. By processing GCM data, using Laterally Constrained Inversion (LCI) and Spatially Constrained Inversion (SCI) algorithms, the values ofelectrical resistivity of the surveyed centers were derived. The results are presented in the form of cross-sections and maps of electrical resistivity from different depths, which were collated and compared with the results from another geophysical method, ERT. These examples show that the use of inversion has a significant impact on the refinement of geological boundaries between layers of different electrical resistivities. Thanks to the correlation of geophysical data with boreholes and engineering geological probes, detailed models of the geological structure of the analyzed areas were elaborated, which are necessary for the selection of appropriate solutions for the construction and modernization of road infrastructure.

16

ERT i GPR – geofizyczne metody badań podłoża wykorzystywane w budownictwie liniowym

Maślakowski M., Józefiak K., Brzeziński K., Superczyńska M.

Przegląd Geologiczny

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2017

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Vol. 65, nr 10/2

765--771

EN

Correct determination of subgrade layers and properties is fundamental for later design and construction stages. Results obtained using traditional geotechnical tests are always of an overly specific nature - information is only provided in certain points in the field. Number of test points and the accuracy of results’ interpretation among them influence the design of an engineering structure foundation, which greatly impacts the cost of a project. Also, the lack of soil testing or insufficient investigation of soil conditions can be the reason for all kinds of legal claims from contractors which often exceed the whole investment budget by several or even several dozen percent. In order to prevent that situation new directives for geotechnical testing include additional geophysical methods such as electrical resistivity tomography (ERT) and ground penetrating radar (GPR). These non-invasive methods can give a spatial image and thus improve the accuracy of soil strata identification. However, these methods have also disadvantages and inaccuracies related to the measurement principles and interpretation of the results. This paper presents limitations and possible errors of geophysical methods ERT and GPR based on example tests carried out for road and railway engineering structures.

17

Geofizyczne monitorowanie procesu podziemnego zgazowania węgla brunatnego

Wojciechowski K.

Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi i Energią PAN

|

2016

|

nr 93

75--82

PL

Z powodu bezszybowego dostępu do złoża skuteczne przeprowadzenie procesu podziemnego zgazowania węgla brunatnego wymaga ciągłego monitorowania geofizycznego. Odpowiada ono za identyfikację położenia frontu zgazowania, modelowanie powstałej kawerny, określenie wpływu gazogeneratora na warstwy nadkładu i osiadanie terenu, jak również pomaga w wykryciu przypuszczalnych ucieczek gazu. Należy wspomnieć, że środowisko naukowe nie wypracowało optymalnego i standaryzowanego systemu monitorowania procesu podziemnego zgazowania węgla brunatnego. Niniejszy artykuł skupia się na wyborze metody obserwacji zjawiska zgazowania dopasowanej do warunków geologicznych towarzyszących polskim węglom brunatnym. Rozpatrywana technologia zgazowania dedykowana jest przede wszystkim pozabilansowym, zawodnionym i zapiaszczonym pokładom węgla brunatnego, występującym w sąsiedztwie utworów ilastych, które za zadanie mają stanowić izolację dla planowanego georeaktora. Wybór metody opiera się na charakterystycznych warunkach panujących w okolicy gazogeneratora, które wywołują lokalne anomalie geofizyczne. Warunki te to przede wszystkim oddziaływanie termiczne gazogeneratora, które wpływa na przewodnictwo elektryczne, porowatość, przepuszczalność, gęstość, czy prędkość rozchodzenia się fal. W efekcie jako najbardziej perspektywiczną metodę wybrano tomografię elektrooporową, która umożliwia niemalże automatyczne monitorowanie procesu. Zaproponowano również metodykę prowadzenia badań, dopasowaną do najbardziej perspektywicznych technologii podziemnego zgazowania węgla brunatnego.

EN

Effective implementation of the brown coal underground gasification process requires continuous geophysical monitoring due to the shaft free access to deposits. Geophysical monitoring is responsible for identifying the gasification front location, modeling formed caverns, determining the impact of the gasifier at layers of overburden and subsidence, as well as helping to detect possible gas escapes. It should be noted that the scientific community did not develop optimal and standardized systems of brown coal underground gasification monitoring. This paper is focused on selecting the gasification monitoring method adapted to the geological conditions accompanying the Polish brown coals. The considered gasification technology is primarily dedicated to off-balance sheet, water-logged and gritty decks of brown coal, occurring near the loams designed to provide insulation for the planned gasifier. The method choice is based on the specific conditions prevailing in the gasifier area, which cause local geophysical anomalies. These conditions are primarily the thermal impact of gasifier which affects the electrical conductivity, porosity, permeability, density, and the waves propagation speed. As a result, electrical resistivity tomography was chosen as the most perspective method which allows for an almost automatic monitoring process, thus it allows the gasifier’s impact on the surroundings to be observed at a relatively low cost. The research methodology, adapted to the most promising technology of brown coal underground gasification was also proposed.

18

Mapping of the north-eastern part of Kozłowicka buried valley based on geoelectrical data

Topolewska S., Stępień M., Kowalczyk S.

Studia Quaternaria

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2016

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Vol. 33, Nr 2

91--101

EN

The paper is aiming to determinate the extent of the northeastern arm of Kozłowicka buried valley on the grounds of own research by means of electrical resistivity tomography – ERT and available archival researches. On the Hydrogeological map of Poland, Żyrardów sheet (Felter and Nowicki, 1998a, b) Kozłowicka buried valley was differentiated as an individual hydrogeological unit. The results of the analysis show that the extent of the structure, defined by its upper boundary, differs significantly from the one suggested on the sheet of Hydrogeological map of Poland. Since there was no data available in the northeastern part of the discussed arm of Kozłowicka buried valley, the northern boundary was defined only based on available geoelectrical sounding profiles (Czerwińska, 1988; Topolewska, 2015). In order to confirm suggested solution, geoelectrical research by means of electrical resistivity tomography (ERT) was conducted. The measurements were performed along 3 profiles located in the area of interest. The authors would like to point out the need of the usage of ERT in mapping and studying buried structures that might be groundwater reservoirs. As a result, one obtains quasi-continuous image of electrical resistivity of the subsurface. Due to the contrast of electrical properties of sediments, it is possible to determine upper and bottom surfaces of electrical properties sediments, it is possible to determine upper and bottom surfaces of buried structures, formed within glacial deposits.

19

Wpływ lokalnej, przypowierzchniowej budowy geologicznej na deformacje powierzchni terenu w warunkach podziemnej eksploatacji górniczej

Niedojadło Z., Piwowarski W., Mościcki W., Sopata P., Stoch T., Bania G., Ćwiklik M.

Przegląd Górniczy

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2016

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T. 72, nr 1

18--26

PL

W publikacji przedstawiono przypadek znaczącej deformacji terenu wywołanej podziemną eksploatacją górniczą, który nie znajduje wytłumaczenia w standardowym modelu zachowania się górotworu. Przyczynę powstania tak silnie destrukcyjnych deformacji należy upatrywać w występującej lokalnie specyficznej budowie geologicznej. Deformacje stwierdzone zostały pomiarami geodezyjnymi prowadzonymi na fragmencie sieci obserwacyjnej zlokalizowanej nad polem górniczym. Powiązanie powstałych na powierzchni terenu deformacji z budową geologiczną możliwe było dopiero po przeprowadzeniu szczegółowych badań geofizycznych. Wyniki zarówno pomiarów geodezyjnych, jak i geofizycznych zostały zaprezentowane i opisane w artykule.

EN

This publication presents the case of land deformations with a strong, destructive impact which cannot be explained based on standard, model behaviour of the rock mass, and the land surface under the conditions of the impact of the underground mining exploitation. The reason for this type of deformation in the case described should be sought in a special geological structure which occurs locally. The deformations were found with the use of geodetic surveys, conducted in the section of the observation network located over the mining field. It was possible to connect the deformations on the land surface with the geological structure only after the detailed geophysical research had been conducted. The results of both the geodetic and geophysical measurements are presented and described in this publication.

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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.