Sebastian Kowalczyk

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

Abstract 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 condi- tions 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.

The usefulness of ground-penetrating radar images for the research of a large sand-bed braided river: case study from the Vistula River (central Poland)

Abstract Ground-penetrating radar (GPR) surveys and sedimentological outcrop analyses were combined in order to determine the reflection patterns and internal architecture of terrace deposits of the Vistula River at Kępa Zawadowska in the southern part of Warsaw (central Poland). The sedimentary analyses concerned the granulometric composition and lithofacies analysis. The 34 GPR profiles, which were obtained in two outcrops, using a Malå RAMAC/GPR system with 500-MHz and 250-MHz shielded antennas, were up to 100 m long. The most characteristic ground-penetrating radar profiles are presented; they show a high-resolution data set of radar facies. The GPR data suggest the presence of three geophysically different units, namely with high-angle inclined reflections (radar facies 1), with discontinuous undulating or trough-shaped reflections (radar facies 2), and with low-angle reflections (radar facies 3). The internal structure of the fluvial deposits was obtained by integration of the GPR and sedimentological data, which combination provides a more accurate visualisation of sedimentary units than do reconstructions that are based only on standard lithologic point data.

Geophysical Survey (GPR) in West Saqqara (Egypt): Preliminary Remarks

Abstract Geophysical investigations in West Saqqara area were part of the archaeological fieldwork of the Polish-Egyptian Archaeological Mission during the campaign in 2012. The main purpose of geophysical prospection using the ground-penetrating radar (GPR) was to determine the location of potential underground sepulchral structures in Saqqara necropolis. During the GPR survey, optimal depth penetration was achieved due to dry rocks and monolithic structure of ancient cemetery. Using antenna of 100 MHz, the depth of penetration was up to 45 m and with antenna of 250 MHz, up to 15 meters. Three main groups of archaeological structures were identified: Greco-Roman sarcophagi and mummies, brick-stone chapels and accompanying burial shafts; mobile objects (solid rock blocks as fragments of tombs). One of the main goal of the GPR survey was to track the route of the western part of the Dry Moat, expressed by a wide and shallow depression spreading towards north-south. It suggests that Saqqara plateau is an ideal site for using GPR surveying technology.

Application of electrical resistivity imaging (ERI) for the assessment of peat properties: a case study of the Całowanie Fen, Central Poland

Complex studies were carried out to recognize the fen structure and peat properties in the Całowanie Fen area, belonging to the Natura 2000 network. The studies were conducted in two study areas that differ significantly in terms of peat thickness. Electrical resistivity imaging (ERI) was used to identify the properties of the peat and its substrate, such as thickness and electrical resistivity. Comparison of the field studies with the laboratory tests has shown that the ash content rises electrical resistivity in peat. In addition, the study has shown that the application of non-invasive geophysical methods in protected areas is justified. The fen, as a medium containing mostly water, was a proper test area for the ERI measurements.

Ground penetrating radar survey in the central and eastern part of the Całowanie Fen, Central Poland

GPR studies were carried out in the Całowanie Fen, a large peatland in the Masovia region (Central Poland) for the identification of the peatland stratigraphy and to create a three-dimensional model for the central and eastern part of the fen. The Całowanie Fen is located within the Masovian Landscape Park on the overflood terrace in the Middle Vistula River Valley. Fen covers an area of about 15 km long and 3km wide. The peatland is located in the abandoned Late Pleistocene Vistula riverbed. The GPR survey was conducted in January 2013 with the Malå RAMAC/GPR system, using 250 MHz frequency shielded antennas. Geophysical measurements were integrated with direct measurements of the peat stratigraphy from drillings. GPR was successfully used to identify the thickness and geometry of the peat layer. The results of GPR measurements provide information about the peat thickness and the possible presence of heterogeneous zones. Maps of peat thickness and the morphology of the mineral peat substrate were compiled based on GPR cross-sections. Considering the success of GPR applications in peatlands, the method seems to represent an excellent alternative to drilling and mapping of stratigraphy and peat thickness.

Sedimentary architecture and ground penetrating radar (GPR) analysis of sandy-gravel esker deposits in Kozlow, Central Poland

The study area is situated near Kozlow village, about 70 km south-east from Warsaw (Central Poland), where relatively young unconsolidated fluvioglacial sediments are mined. The excavated sandy-gravel body is built up by architectural elements typical for esker deposits. Ground penetrating radar (GPR) surveys and sedimentological outcrop analyses are combined in order to characterize reflection patterns, internal architecture and to assess the GPR methods potential for imaging of Quaternary fluvioglacial deposits. Ground penetrating radar is a non-invasive tool which allows visualization of the subsurface so that excavations or point data are unnecessary. The results show that the sediments deposited by the glacier meltwater produce characteristic radar facies, which can be observed in sandy-gravel pit. Representative research points were selected where the GPR data could be directly correlated and compared with sedimentary information derived from exposures thus, geomorphological data could be provided. The study generated a high resolution data set of lithofacies and ground penetrating radar profiles. The results obtained for the study area show that integration of sedimentological data with geophysical imaging (GPR) enables the identification of stratigraphie units at the scale of depositional elements. Gridded ground penetrating radar surveys hold promise for 3-dimensional discovery of stratigraphy in the Kozlow esker and in other fluvioglacial deposits in Central Poland. The integration of sedimentological and GPR results provides a more accurate description and visualization of sedimentary units compared to reconstructions based solely on point data.

Stateczność zbocza i zagrożenie osuwiskowe w świetle kompleksowych badań geologicznych

Jednym z podstawowych elementów planowania i rozwoju przestrzennego jest wszechstronna analiza warunków naturalnych, między innymi: ukształtowania terenu, klimatu i warunków gruntowo-wodnych. Powierzchnie nachylone zazwyczaj stwarzają utrudnienia w zagospodarowaniu i wymagają specjalnego podejścia badawczego i projektowego. Zgodnie z aktualnymi wytycznymi dla budowli usytuowanych na zboczach czy skarpach, a także w ich sąsiedztwie zalecane jest przeprowadzenie oceny stateczności. W niniejszym artykule przedstawiono propozycję wielowątkowego podejścia do zagadnienia stateczności wybranego zespołu osuwiskowego zlokalizowanego w Polsce południowej i doboru parametrów do symulacji warunków stanu równowagi. Problematyka jest o tyle aktualna i istotna, że dotyczy wielu lokalizacji na terenie naszego kraju, a ponadto znajduje odzwierciedlenie w zmianach w ustawodawstwie w zakresie budownictwa na terenach osuwiskowych, ich sąsiedztwie oraz na terenach zagrożonych ruchami masowymi. Przegląd Naukowy – Inżynieria i Kształtowanie Środowiska (2017), 26 (1), 85–98 Prz. Nauk. Inż. Kszt. Środ. (2017), 26 (1) Scientifi c Review – Engineering and Environmental Sciences (2017), 26 (1), 85–98 Sci. Rev. Eng. Env. Sci. (2017), 26 (1) http://iks.pn.sggw.pl DOI 10.22630/PNIKS.2017.26.1.08

Mapping of the North-Eastern Part of Kozłowicka Buried Valley Based on Geoelectrical Data

Abstract The paper is aiming to determinate the extent of the north eastern arm of Kozłowicka buried valley on the grounds of own re search by means of electrical resistivity tomography- ERT and avail able archival researches. On the Hydro-geological map of Poland, Żyrardów sheet (Felter and Nowicki, 1998a, b) Kozłowicka buried valley was differentiated as an individual hydro-geological unit. The results of the anal y sis show that the ex tent of the structure, defined by its up per boundary, differs significantly from the one suggested on the sheet of Hydrogeological map of Poland. Since there was no data avail able in the north eastern part of the dis cussed arm of Kozłowicka buried valley, the northern boundary was defined only based on avail able geoelectrical sounding profiles (Czerwiñska, 1988; Topolewska, 2015). In order to confirm suggested solution, geoelectrical re search by means of electrical resistivity tomography (ERT) was con ducted. The measurements were per formed along 3 pro files located in the area of interest. The authors would like to point out the need of the us age of ERT in map ping and studying buried structures that might be ground water 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 buried structures, formed within glacial deposits.

Fluvial architecture of Vistula River deposits in Nature Reserve Świderskie Islands (Warsaw area, central Poland) based on Ground Penetrating Radar (GPR) images

Ground Penetrating Radar (GPR) investigations were conducted in order to characterize the reflection patterns and internal architecture of Vistula River point bars. The study area is situated in the south part of Warsaw (Central Poland), in the Nature Reserve Swiderskie Islands, where fluvial deposits were well accessible due to an unusually low water level in the Vistula River. Ground Penetrating Radar is a non-invasive tool that facilitates easy and quick investigations of subsurface sediments. The study was based on 7 GPR profiles taken on the largest and most accessible point bar. All profiles were collected using ProEx Malâ GPR system with 250 MHz shielded antenna. In this paper characteristic Ground Penetrating Radar profiles are presented, to show the internal architecture of fluvial deposits. Interpretation of selected GPR profiles showed the presence of erosional surfaces and cut-in channels within the investigated point bar.

Applicability of Ground Penetrating Radar on desert archaeological sites: a case study from the Saqqara necropolis in Egypt

Abstract This paper presents the preliminary results of ground penetrating radar sounding applied at the desert archaeological site in Saqqara (Egypt). The survey was carried out in 2012 within a project realized by Institute of Archaeology, Cardinal Stefan Wyszyński University in Warsaw and the Faculty of Geology, University of Warsaw. One of the key aims of the research was testing the application of ground penetrating radar to non-invasive surveys of desert archaeological sites. Radargrams obtained for area of so called the Dry Moat channel surrounding the Step Pyramid complex have shown the geological structure of its filling. It comprises among others debris-sand conglomerate of diluval origin characterized by a significant content of the clay fraction and clay minerals. Such lithological content strongly attenuate the propagation of EM waves, restricting the depth range of the GPR survey. The conducted geophysical prospection west to the Step Pyramid in Saqqara has confirmed the high applicability of the GPR method in non-invasive studies of vast architectural structures, such as the monumental ditch surrounding the Step Pyramid known as the Dry Moat. It should summarised that high horizontal resolution obtained during GPR survey is a result of local geological structure of the searched area, i.e. strong lithological contrast of the sediments filling the Dry Moat, which, depending on their mineralogical composition