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Petroleum Geo-Electrical Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
GPR uses the radio wave portion of the electromagnetic radiation consisting of 102 to 108 Hz frequency and wavelength from 102 to 106 meters. The radio waves travel with a faster speed in matter than in air. The subsurface propagation of radar wave obeys the same law as seismic waves. The velocity of a radar wave (V) in the subsurface is controlled by the electrical properties of the rock materials, notably resistivity, conductivity and electrical permittivity. Electrical permittivity and resistivity are defined by the ‘dielectric constant’ of a semi-conductor (rock material). The dielectric constant is a measure of relative permittivity more than the resistivity. The dielectric constant of water is 80 and it is considered a highly electric conducting material, whereas rock materials have a dielectric constant of 4.0 to 50.0. The materials with a dielectric constant of less than 8 are considered poor conductors or good insulators. The presence of pore water and ionizable minerals in the rock makes the rock conductor. In homogenous subsurface rock the propagation of radar waves is linear, though of course diminishing in energy (amplitude) with the passage of time and depth penetrated.
Geophysical Applications
Published in Stephen M. Testa, Geological Aspects of Hazardous Waste Management, 2020
GPR employs radio waves that are projected, reflected, and then recovered at an antenna moving across the surface of the ground (Figure 6-1). Variations in the return signal are continuously recorded to produce a continuous crosssectional profile of shallow subsurface conditions (Figures 6-2 and 6-3).
Smart Perception System for Subsurface Robot Mapping: From Simulation to Actual System Realization
Published in Huansheng Ning, Liming Chen, Ata Ullah, Xiong Luo, Cyber-Enabled Intelligence, 2019
Ioannis Kostavelis, Dimitrios Giakoumis, Evangelos Skartados, Andreas Kargakos, Dimitrios Tzovaras
To achieve large-scale automated data acquisition of subsurface data, the GPR sensor is typically integrated with wheeled mobile vehicles. In our approach we assumed the existence of a GPR antenna that is an array of GPR sensors placed on specific rigid topology. Moreover, the GPR antenna is towed by a wheeled mobile vehicle to allow coverage of long distances and, thus, to facilitate large subsurface perception capacity. The working principal of GPR relies on the transmission of electromagnetic pulses into the ground at frequencies usually in the range of 10–4000 MHz, depending on the design of the device and the target application [1]. While the signal is traveling in the subsurface, when it encounters an interface between layers of differing permittivity, part of the energy is reflected back to the surface while the remainder is diffracted from the subjacent medium. The reflection/diffraction process continues until the signal has weakened completely or the amount of time that the GPR receiver is programmed to search for a return signal (design principal of GPR device) has passed.
Geomorphic mapping and analysis of neotectonic structures in the piedmont alluvial zone of Haryana state, NW-India: a remote-sensing and GPR based approach
Published in Geomatics, Natural Hazards and Risk, 2023
Harsh Kumar, R. S. Chatterjee, R. C. Patel, Abhishek Rawat, Somalin Nath
GPR survey is a high resolution, non-invasive geophysical measurement method that allows the investigation of the shallow sub-surface on the basis of dielectric properties of the layers. GPR is an important tool ideally suited for obtaining high resolution profiles of the sub surface over a depth range of a few metres to several tens of metres with a vertical resolution of a few tens of centimetres to a metre (Basson 2000; Knight 2001). GPR studies have been conducted to detect the near-surface Quaternary deformations, near-surface faults in unconsolidated sediments, palaeoliquefaction-tectonic deformations, and earthquake subsidence events (Maurya et al. 2005). GPR is ideally suited for detecting and imaging geological features between the surface and a depth of several tens of metres, to construct a complete picture of subsurface features caused by earthquakes and other tectonic events.
Ground penetrating radar applications and implementations in civil construction
Published in Journal of Structural Integrity and Maintenance, 2023
Macy Spears, Saman Hedjazi, Hossein Taheri
The antenna setup that is employed during testing is a key factor that affects the results, and the decision depends on the purpose for evaluation. The two types of GPR antenna structures are air-launched and ground-coupled antennas. Air-launched antennas are those that are elevated above the tested surface and typically attached to a vehicle or cart where the signals are sent through the air to the ground. Ground-coupled antennas involve the placement of antennas directly on or close to the surface of the test object. Both methods have advantages and limitations to acknowledge. While air-coupled antennas can collect data at a faster rate, there are high reflection losses between layers, reducing the penetration depth (Eide et al., 2014). Using ground-coupled antennas can be more effective since they have the potential to integrate more energy in the surface and probe at greater depths (Zhang et al., 2020). An example of a ground-coupled antenna arrangement for a GPR system attached to a vehicle is shown in Figure 3, which was created by Eide et al. and used for bridge deck and road inspection (Eide et al., 2014). However, GPR hardware is constructed in various shapes and forms, depending on the purpose for testing.
Development of a fully planar logarithmic spiral antenna with integrated balun in UWB GPR systems for landmines detection
Published in Electromagnetics, 2022
Narek Grigoor-Feghi, Reza Masoumi, Robab Kazemi
Ground penetrating radar (GPR) is a nondestructive evaluation technique that uses electromagnetic waves for imaging underground objects. GPR can be used for detection of buried objects, changes in material properties, cavities, and cracks (Kazemi 2018). The problem of landmine pollution affects many countries around the world and is exacerbated by ongoing armed conflict around the world. Mine clearance methods include the use of metal detectors, GPRs, trained dogs, and infrared imaging (He and Akizuki 2010). Figure 1 shows a block diagram of a typical GPR system. In this system, electromagnetic waves are radiated from a transmitter and penetrate into the ground. Then, the reflected/back-scattered waves are collected by a receiver. According to the speed of these received waves, which have various speeds in different environments, underground informations such as type of the environment, presence of buried objects, depth of the buried objects, the layers of the earth and so on can be obtained.