scholarly journals High frequency impulse ground penetrating radar application in assessment of interlayer connections

2018 ◽  
Vol 163 ◽  
pp. 02005 ◽  
Author(s):  
Jacek Sudyka ◽  
Lech Krysiński ◽  
Adam Zofka ◽  
Marek Pszczoła ◽  
Piotr Jaskuła
Keyword(s):  
Ground Penetrating Radar ◽  
High Frequency ◽  
Large Scale ◽  
Measuring System ◽  
Electromagnetic Properties ◽  
Electromagnetic Responses ◽  
Pavement Structures ◽  
Zero Offset ◽  
Ground Penetrating ◽  
Frequency Impulse

Ground Penetrating Radar (GPR) technique is commonly used in the nondestructive evaluation of pavement structures. In particular, this method is used to estimate thicknesses of pavement layers as well as it can be utilized in advanced studies of pavement structures. The device presented in this paper comprise the high frequency impulse antennas that allow for investigating the interlayer zones in terms of their electromagnetic properties (e.g. dielectric constant). In some cases these electromagnetic responses can be suitable in the assessment of layer bonding in the pavement structure. This paper discusses the assessment of the quality of asphalt pavement interlayer bonding with the use of high frequency GPR techniques. The preliminary laboratory measurements were performed using an impulse antenna in the zero-offset configuration combined with the large-scale models simulating an idealized horizontal delamination. These measurements allowed to estimate the antenna sensitivity to detect interlayer connection under dry and wet conditions. Analysis of collected results led to formulating practical conclusions regarding critical limitations of the measuring system and adequate methods of signal processing and interpretation. The field investigations consisted of the GPR measurements along selected road sections and collection of the core samples at the locations associated with the specific reflexes. Inspection of the cores provided some real insights into the structure of different delaminations associated with characteristic reflexes. Analysis showed the reflection properties are able to expresses some important features of the interlayer zone, such as delaminations, presence of alien material at the interface, insufficient compaction occurring at the base of layer, and water penetration.

Effects of magnetite on high-frequency ground-penetrating radar

Geophysics ◽  
2013 ◽  
Vol 78 (5) ◽  
pp. H1-H11 ◽  
Author(s):  
Remke L. Van Dam ◽  
Jan M. H. Hendrickx ◽  
Nigel J. Cassidy ◽  
Ryan E. North ◽  
Mine Dogan ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
High Frequency ◽  
Laboratory Experiments ◽  
Parent Material ◽  
Electromagnetic Properties ◽  
Small Scale ◽  
Shallow Subsurface ◽  
Propagation Behavior ◽  
Ground Penetrating ◽  
Reflection Characteristics

Large concentrations of magnetite in sedimentary deposits and soils with igneous parent material have been reported to affect geophysical sensor performance. We have undertaken the first systematic experimental effort to understand the effects of magnetite for ground-penetrating radar (GPR) characterization of the shallow subsurface. Laboratory experiments were conducted to study how homogeneous magnetite-sand mixtures and magnetite concentrated in layers affect the propagation behavior (velocity, attenuation) of high-frequency GPR waves and the reflection characteristics of a buried target. Important observations were that magnetite had a strong effect on signal velocity and reflection, at magnitudes comparable to what has been observed in small-scale laboratory experiments that measured electromagnetic properties of magnetite-silica mixtures. Magnetite also altered signal attenuation and affected the reflection characteristics of buried targets. Our results indicated important implications for several fields, including land mine detection, Martian exploration, engineering, and moisture mapping using satellite remote sensing and radiometers.

scholarly journals Ground‐penetrating radar: Analysis of point diffractors for modeling and inversion

Geophysics ◽  
2001 ◽  
Vol 66 (2) ◽  
pp. 540-550 ◽  
Author(s):  
Albane C. Saintenoy ◽  
Albert Tarantola
Keyword(s):  
Ground Penetrating Radar ◽  
Electromagnetic Properties ◽  
Radiation Patterns ◽  
Property Variation ◽  
Diagnostic Interpretation ◽  
Reflection Data ◽  
The Earth ◽  
Zero Offset ◽  
Ground Penetrating ◽  
And Inversion

The three electromagnetic properties appearing in Maxwell’s equations are dielectric permittivity, electrical conductivity and magnetic permeability. The study of point diffractors in a homogeneous, isotropic, linear medium suggests the use of logarithms to describe the variations of electromagnetic properties in the earth. A small anomaly in electrical properties (permittivity and conductivity) responds to an incident electromagnetic field as an electric dipole, whereas a small anomaly in the magnetic property responds as a magnetic dipole. Neither property variation can be neglected without justification. Considering radiation patterns of the different diffracting points, diagnostic interpretation of electric and magnetic variations is theoretically feasible but is not an easy task using ground‐penetrating radar. However, using an effective electromagnetic impedance and an effective electromagnetic velocity to describe a medium, the radiation patterns of a small anomaly behave completely differently with source‐receiver offset. Zero‐offset reflection data give a direct image of impedance variations while large‐offset reflection data contain information on velocity variations.

scholarly journals Study Effect of Objects Orientation in the Mediums On GPR Signal Reflections Using FDTD Simulation

2018 ◽  
Vol 3 (11) ◽  
pp. 73-77
Author(s):  
Aye Mint Mohamed Mostapha ◽  
Gamil Alsharahi ◽  
Abdellah Driouach
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Ground Penetrating Radar ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Ground Surface ◽  
Propagation Path ◽  
Fdtd Simulation ◽  
Ground Penetrating ◽  
Dielectric Objects

Ground penetrating radar (GPR) is a very effective tool for detecting and identifying objects below the ground surface.  based on  the propagation and reflection of high-frequency electromagnetic waves. The GPR reflection can be affected by many things like the type of objects orientation, their shapes ..ect. The purpose of this paper is to  study by simulation the effect of objects orientation in two different mediums (dry and wet sand) on the GPR signal reflection using Reflexw software which is based on a numerical method known as finite difference in time domain (FDTD).  The simulations that have been realized included a conductor  and dielectric objects. The results obtained have led us to find that the propagation path, the reflection strength and the signal form change with the change of object orientation and nature. To confirm the validity of the results, we compared them with experimental results previously published by researchers under the same conditions.

Model Track Studies by Ground Penetrating Radar (GPR) on Ballast With Different Fouling and Geotechnical Properties

2015 ◽  
Author(s):  
Hamed Faghihi Kashani ◽  
Carlton L. Ho ◽  
Charles P. Oden ◽  
Stanley S. Smith
Keyword(s):  
Ground Penetrating Radar ◽  
Large Scale ◽  
Empirical Studies ◽  
Geotechnical Properties ◽  
Maintenance Cost ◽  
Non Invasive ◽  
Section Area ◽  
University Of Massachusetts ◽  
Ground Penetrating ◽  
The University

In recent years there has been an increase in the knowledge of, and need for, non-invasive monitoring of ballast in order to identify the problematic sections of track and decrease the maintenance cost. Various technologies such as Ground Penetrating Radar (GPR) are becoming accepted for investigating the condition of ballast. However since these techniques were not originally developed for engineering applications, their applicability in ballast evaluations can be sometimes uncertain. Continued empirical studies and condition specific calibrations are needed to demonstrate repeatable and quantifiable results. In this study large-scale track models with trapezoidal section area were constructed at the University of Massachusetts to investigate the effects of breakdown fouling, and the effects of changing geotechnical properties on GPR traces. This paper presents the design and construction of large scale track models, and methods used for GPR data collection. GPR data are presented in this paper that demonstrate sensitivity to the track model properties and variables. In particular, the experiments are being used to evaluate changes in GPR data with changing geotechnical properties of the ballast such as density, water content, grain size distribution (GSD), and fouling percentage.

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