Abstract
In this paper, the Ground Penetrating Radar (GPR) method was used to characterize concrete tubes and steel/plastic tanks buried in IAG/USP test site. The microwave tomography was used to improve the GPR images, aiming to retrieve the geometry of the targets. The numerical modeling studies also were done in order to predict the GPR results of the buried targets and to give more reliability to the results interpretation. The targets were installed in the first shallow geophysical test site of the Brazil located at Institute of Astronomy, Geophysics, and Atmospheric Science (IAG) of the University of Sao Paulo (USP). GPR profiles of 200 MHz (shielded bistatic antennas) were acquired along three lines containing concrete tubes and steel/plastic tanks buried in subsoil. The concrete tubes show a hyperbolic reflector for the top, and the vertical tube also presented a reflection on its bottom. The horizontal steel tanks were characterized by a strong GPR reflection on their top. The empty plastic tank shows a strong reflector for the top with normal polarity. On the other hand, the plastic tank filled with water shows a weaker reflector for its top characterized by the inverted polarity of GPR signal when compared with empty plastic tank. The plastic tank filled with water also went characterized by the strong reflection to its bottom, being a good indicative to interpret GPR data on target in subsoil with some types of fluid inside of tank. The results of polarity difference for the top of tank can be used as guide pattern to identify buried tank empty or filled with water. The application of microwave tomography to the GPR data permitted to determine the position and get a good identification of the edges of the targets studied. The numeric modeling presented a good accordance with real data reducing the ambiguities in interpretation of results. These results can be used as a reference, and they can be extrapolated for areas where there is no subsurface information.
Highlights
The Ground Penetrating Radar (GPR) is a geophysical method that uses electromagnetic waves in high frequency (10 MHz to 2.6 GHz) and has innumerable applications for shallow subsurface investigations, such as urban problems, infra-structure, environmental studies, mineral exploration, geological, hydrogeological, and archaeological studies
This paper presents some results of GPR modeling, standard processing and microwave tomography application in GPR data, over empty concrete tubes, empty steel tanks and plastic tanks buried in the IAG/University of São Paulo (USP) test site [12] in order to characterization these targets that usually are present in the subsoil of the large cities of the world
The IAG/USP geophysical test site is pioneer in Brazil, and it was constructed at University of São Paulo campus for teaching and research purposes
Summary
The Ground Penetrating Radar (GPR) is a geophysical method that uses electromagnetic waves in high frequency (10 MHz to 2.6 GHz) and has innumerable applications for shallow subsurface investigations, such as urban problems, infra-structure, environmental studies, mineral exploration, geological, hydrogeological, and archaeological studies. The use of geophysical methods can prevent dangerous accidents and minimize the risk situations for society. The GPR study was performed under controlled conditions in the IAG/USP geophysical test site in order to obtain the better understanding the normal reflection patterns caused by different targets in the subsoil. This paper presents some results of GPR modeling, standard processing and microwave tomography application in GPR data, over empty concrete tubes, empty steel tanks and plastic tanks (empty and filled with water) buried in the IAG/USP test site [12] in order to characterization these targets that usually are present in the subsoil of the large cities of the world. The goal is to define the target location This information serves as basis for planning the advance of geotechnical excavations in urban. Centers because it helps minimize problems related to the damage or destruction of preexisting underground utilities, and avoid dangerous accidents
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