Wyniki wyszukiwania - BazTech

1

Theoretical aspects and numerical modelling of the GPR method to analyse its possibilities for the detection of leakages in urban water supply networks

Gołębiowski Tomisław

Geology, Geophysics and Environment

|

2023

|

Vol. 49, no. 4

357--373

EN

Geophysical methods, especially selected electrical and electromagnetic ones, have been used for many years for the non-invasive detection of leakages from water supply networks. In this paper, the author focuses on theoretical aspects and numerical simulations to analyse the possibilities and limitations of the application of the selected electromagnetic method, i.e., the ground-penetrating radar (GPR) method for the aforementioned purpose. Various measurement techniques are used in the GPR method but in the paper the author refers to the most commonly used technique known as short-offset reflection profiling (SORP). As demonstrated in the paper, the detection of water leakages into a homogeneous and isotropic geological medium using the GPR method is a simple matter. However, the detection of leakages occurring in heterogeneous ground subjected to strong anthropopression and with the presence of electromagnetic interference becomes a difficult task, and interpretation may be difficult or even impossible. An important issue analysed in the paper was the phenomenon of the scattering of electromagnetic waves on underground anthropogenic objects, which very often occurs in urbanised areas. The results of the numerical modelling carried out for various scenarios of water leakages into typical ground allowed the possibilities and limitations of using the GPR method for the detection of leakages from water supply networks to be determined.

2

GPR signal analysis for the exploration of loose zones in the near surface underground

Gołębiowski Tomisław

Geoinformatica Polonica

|

2023

|

T. 22

21--33

EN

In the paper, non-standard signal and image processing applied for the GPR (Ground Penetrating Radar) data record for various antennae orientations was presented and discussed. The terrain surveys were carried out in the post-mining region in Poland where numerous sinkholes and subsidence areas were observed on the surface due to the former mining activity. The GPR surveys were conducted between two existing sinkholes and the aim of measurements was detection of loose zones in the ground created by suffosion process which caused the formation of the mentioned two sinkholes. In the paper, the Author proposed a new way of processing and analysis of radargrams based on three steps, i.e. 1D more advanced processing of signals/traces, 2D more advanced image processing of combined radarogram, visualisation and analysis of selected signal attributes.

PL

W artykule przedstawiono i omówiono niestandardowe metody przetwarzania sygnałówi obrazów georadarowych GPR (Ground Penetrating Radar) dla różnych orientacji anten pomiarowych. Badania terenowe przeprowadzono na wybranym obszarze pogórniczym w Polsce, gdzie zaobserwowano na powierzchni terenu liczne zapadliska i strefy osiadań wywołane dawną działalnością górniczą. Badania GPR przeprowadzono pomiędzy dwoma istniejącymi zapadliskami. Celem pomiarów było wykrycie stref rozluźnień w gruncie powstałych w wyniku procesów sufozyjnych, który wcześniej spowodował powstanie wspomnianych dwóch zapadlisk. W artykule zaproponowano nowy sposób przetwarzania i analizy radarogramów oparty na trzech etapach, tj. bardziej zaawansowane przetwarzanie 1D sygnałów/tras, bardziej zaawansowane przetwarzanie 2D obrazu powstałego z połączenia radarogramów i finalnie wizualizację oraz analizę wybranych atrybutów sygnałów georadarowych.

3

Application of GPR and seismic methods for noninvasive examination of glacial and postglacial sediments in the Psia Trawka glade: the Tatra Mts., Poland

Tomecka-Suchoń Sylwia, Gołębiowski Tomisław, Dec Jerzy, Magiera Janusz

Acta Geophysica

|

2019

|

Vol. 67, no. 6

1777--1789

EN

Presented study gives an insight into general proportions of the actual geomorphology, subglacial morphology and thickness of the drift (quaternary sediments) particularly well-pronounced glacial morphology in the Tatras and, on the other hand, the general scarcity of the data in this field. Objectives of the geophysical survey in this study were imaging of the morphology of bedrock surface under the drift (glacial and postglacial) sediments and determination of thickness of the drift and its composition. Two methods were applied: Ground Penetrating Radar (GPR) and seismic refraction profiling. GPR was used to examine drift sediments due to its high resolution and low depth of penetration. Seismic method with lower resolution but higher penetration depth gave an image of boundary between bedrock and drift. In addition, the results of seismic tomography allowed the velocity field imaging which shows changes inside the postglacial deposits. The results of the two methods used in this research suggest that points of depression exist in the subglacial morphology with a depth of about c.a. 40 below the present-day terrain surface and c.a. 25 m below surrounding subglacial surface. This trough has also been estimated to be about 150 m wide. Its considerable depth and steep slopes show that its origin can be related to erosion of subglacial water during the decay of the last (Würm) glaciation of the Sucha Woda and Panszczyca valleys.

4

Application of GPR and ERT methods for recognizing of gypsum deposits in urban areas

Gołębiowski Tomisław, Jarosińska Elżbieta

Acta Geophysica

|

2019

|

Vol. 67, no. 6

2015--2030

EN

This paper presents the selected results of GPR (ground penetrating radar) and ERT (electrical resistivity tomography) surveys carried out on the sites in Poland where shallow karst forms were found in gypsum deposits. The aim of the surveys was the noninvasive detection of karst forms as well as weathered and fractured bedrock which may threaten the stability of the surface and, consequently, may cause damage to buildings, as well as overground and underground infrastructure. The geophysical surveys were conducted at a depth of only a few meters, i.e., to the depth of buildings foundations. GPR surveys were carried out in short-offset reflection profiling mode with standard orientation of the antennae set; however, on one site, different orientations of antennae were tested. During ERT surveys, different measurement arrays were applied in order to analyze which array was optimal for the detection of karst forms as well as weathered and fractured bedrock. Complex interpretation of geophysical surveys resulted in reduced ambiguity and revealed some regions, dangerous for surface stability. Due to the fact that gypsum deposits were investigated to the depth of maximum 10 m; therefore, hydrological processes were analyzed in the paper instead of hydrogeological processes.