Ground-Penetrating Radar, Chain Drag, and Ground Truth

2008 ◽  
Vol 2044 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Sherif Yehia ◽  
Osama Abudayyeh ◽  
Ikhlas Abdel-Qader ◽  
Ammar Zalt
Keyword(s):  
Ground Penetrating Radar ◽  
Ground Truth ◽  
Ground Penetrating

Ground-penetrating radar data diffraction focusing without a velocity model

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. H13-H24
Author(s):  
Nikos Economou ◽  
Antonis Vafidis ◽  
Maksim Bano ◽  
Hamdan Hamdan ◽  
Jose Ortega-Ramirez
Keyword(s):  
Ground Penetrating Radar ◽  
Constant Velocity ◽  
Electromagnetic Waves ◽  
Ground Truth ◽  
Velocity Model ◽  
Migration Velocity ◽  
Dominant Frequency ◽  
Limited Information ◽  
Velocity Range ◽  
Ground Penetrating

Ground-penetrating Radar (GPR) sections commonly suffer from strong scattered energy and weak reflectors with distorted lateral continuity. This is mainly due to the gradual variation of moisture with depth, dense lateral sampling of common-offset GPR traces (which are considered as zero-offset data), along with the small wavelength of the electromagnetic waves that is comparable to the size of the shallow subsurface dielectric heterogeneities. Focusing of the diffractions requires efficient migration that, in the presence of highly heterogeneous subsurface formations, can be improved by a detailed migration velocity model. Such a velocity model is difficult to develop because the common-offset antenna array is mostly used for its reduced time and cost in the data acquisition and processing stages. In such cases, migration processes are based on limited information from velocity analysis of clear diffractions, cores, or other ground truth knowledge, often leading to insufficient imaging. We have developed a methodology to obtain GPR sections with focused diffractions that is based on multipath summation, using weighted stacking (summation) of constant-velocity migrated sections over a predefined velocity range. The success of this method depends on the assignment of an appropriate weight, for each constant-velocity migrated section to contribute to the final stack, and the optimal width of the velocity range used. Additionally, we develop a postmultipath summation processing step, which consists of time-varying spectral whitening, to deal with the decrease of the dominant frequency due to attenuation effects and the additional degraded resolution expected by the constant migration summed images. This imaging strategy leads to GPR sections with sufficiently focused diffractions, enhancing the lateral and the temporal resolution, without the need to explicitly build a migration velocity model.

scholarly journals The Fortress Beneath: Ground Penetrating Radar Imaging of the Citadel at Alcatraz: 1. A Guide for Interpretation

Heritage ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 1328-1347
Author(s):  
Mark E. Everett ◽  
Timothy S. DeSmet ◽  
Robert R. Warden ◽  
Henry A. Ruiz-Guzman ◽  
Peter Gavette ◽  
...  
Keyword(s):  
Cultural Heritage ◽  
Ground Penetrating Radar ◽  
Ground Truth ◽  
Companion Paper ◽  
Evaluation Tool ◽  
Facies Classification ◽  
Central Interest ◽  
Advanced Analysis ◽  
Ground Penetrating ◽  
The 19Th Century

Ground-penetrating radar has emerged as a prominent non-destructive evaluation tool for the study of inaccessible subsurface elements of cultural heritage structures. Often of central interest is the desire to image the remains of a pre-existing historic structure that is located directly beneath a more recently built one. The interpretation of GPR images in such cases is usually difficult due to ambiguities caused by the presence of pervasive clutter, environmental noise, and overlapping target signatures. Sites with abundant ground truth allow for more confident interpretations and serve as a useful testbed to assist similar studies at other places, where little or no ground truth is available. This study reports GPR interpretations of structures belonging to the 19th century Citadel beneath the main prison cellhouse at Alcatraz. At this site, lidar scans, direct observations, and historical documents are available to facilitate identification of radar target signatures. A general interpretation of the acquired radargrams is made in this paper, while the companion paper presents more advanced analysis of target signatures based on curvelet image processing. This study points to the development of a radar facies classification scheme that is specific to cultural heritage investigations.

scholarly journals Practical Approach for High-Resolution Airport Pavement Inspection with the Yakumo Multistatic Array Ground-Penetrating Radar System

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2684 ◽  
Author(s):  
Li Yi ◽  
Lilong Zou ◽  
Motoyuki Sato
Keyword(s):  
Ground Penetrating Radar ◽  
Estimation Method ◽  
Ground Truth ◽  
Radar System ◽  
Velocity Estimation ◽  
Velocity Spectrum ◽  
Airport Pavement ◽  
Ground Penetrating ◽  
Airport Site ◽  
Good Agreement

It is important to identify the thin cracks within the airport pavement layers. To achieve this goal, a practical interferometric approach using the Yakumo multistatic ground-penetrating radar system was developed to detect the slight variability in wave propagation velocity and/or thickness caused by the thin cracks. In comparison with the conventional common midpoint (CMP) velocity estimation method, the proposed method can provide much higher-resolution estimations of slight deviations in the velocity and thickness from their corresponding reference values in the undamaged asphalt through the comparison of two CMP datasets. These deviations can be obtained analytically instead of graphically extracted from the CMP velocity spectrum. The proposed approach was not only analyzed using the simulated datasets, but also practically demonstrated at both an experimental model site and an actual airport site. In the simulation tests, velocity deviations on the order of a few millimeters per nanosecond were detected, and the experimental results shows good agreement with the ground truth and coring samples. This method provides a novel way to inspect partially damaged pavement when the thin cracks are difficult to detect using the reflected signals.

Detecting Stripping in Asphalt Concrete Layers Using Ground Penetrating Radar

1997 ◽  
Vol 1568 (1) ◽  
pp. 165-174 ◽  
Author(s):  
Elias Rmeili ◽  
Tom Scullion
Keyword(s):  
Ground Penetrating Radar ◽  
Ground Truth ◽  
Department Of Transportation ◽  
Portland Cement Concrete ◽  
Design Decisions ◽  
Texas Department ◽  
1960S And 1970S ◽  
The 1960S ◽  
Ground Penetrating ◽  
Asphalt Overlays

A study undertaken by the Texas Department of Transportation to nondestructively detect stripping in the asphalt surfacing on I-45 in the Bryan district is described. The highway was constructed in the 1960s and 1970s with an initial portland cement concrete thickness of 200 mm. Since then, several asphalt overlays have been applied. Maintenance of this highway is a recurring problem, and it is known that in several locations moderate to severe areas of subsurface stripping are present. To plan the future rehabilitation of this important highway, the Bryan district investigated the ability of ground penetrating radar (GPR) to provide subsurface condition information. A GPR survey was conducted at close to highway speeds, and the data were interpreted before taking validation cores. The GPR was used to provide information concerning the section breaks along the highway on the basis of asphalt layer thickness and condition, the average thickness of the asphalt layer within each section, and the extent and severity of any defect in the asphalt layer. More than 60 cores were taken to correlate the GPR interpretation. GPR results and ground truth cores are compared. In general, the comparisons were good. The GPR equipment and interpretation schemes used were found to provide information of sufficient quality and accuracy to permit the district to make programming decisions. GPR is now being used on several additional projects in the Bryan district. The best use appears to be for both defect detection and thickness estimation before deflection testing and coring. GPR will not eliminate coring or deflection testing, but by using all three in a coordinated approach pavement designers will have more confidence in their design decisions.

REFLECTION COEFFICIENT OF AN ELECTROMAGNETIC WAVE IN CONDUCTIVE MEDIA

2018 ◽  
pp. 100-106
Author(s):  
M. S. Sudakova ◽  
M. L. Vladov ◽  
M. R. Sadurtdinov
Keyword(s):  
Reflection Coefficient ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Water Contamination ◽  
Survey Design ◽  
Direct And Inverse Problems ◽  
The Difference ◽  
Ground Penetrating ◽  
Ideal Dielectric

Within the ground penetrating radar bandwidth the medium is considered to be an ideal dielectric, which is not always true. Electromagnetic waves reflection coefficient conductivity dependence showed a significant role of the difference in conductivity in reflection strength. It was confirmed by physical modeling. Conductivity of geological media should be taken into account when solving direct and inverse problems, survey design planning, etc. Ground penetrating radar can be used to solve the problem of mapping of halocline or determine water contamination.

Deteksi Bentuk Objek Bawah Tanah Menggunakan Pengolahan Citra B-Scan pada Ground Penetrating Radar (GPR)

2017 ◽  
Vol 3 (1) ◽  
pp. 73-83
Author(s):  
Rahmayati Alindra ◽  
Heroe Wijanto ◽  
Koredianto Usman
Keyword(s):  
Signal Processing ◽  
Ground Penetrating Radar ◽  
Post Processing ◽  
Data Survey ◽  
Ground Penetrating

Ground Penetrating Radar (GPR) adalah salah satu jenis radar yang digunakan untuk menyelidiki kondisi di bawah permukaan tanah tanpa harus menggali dan merusak tanah. Sistem GPR terdiri atas pengirim (transmitter), yaitu antena yang terhubung ke generator sinyal dan bagian penerima (receiver), yaitu antena yang terhubung ke LNA dan ADC yang kemudian terhubung ke unit pengolahan data hasil survey serta display sebagai tampilan output-nya dan post  processing untuk alat bantu mendapatkan informasi mengenai suatu objek. GPR bekerja dengan cara memancarkan gelombang elektromagnetik ke dalam tanah dan menerima sinyal yang dipantulkan oleh objek-objek di bawah permukaan tanah. Sinyal yang diterima kemudian diolah pada bagian signal processing dengan tujuan untuk menghasilkan gambaran kondisi di bawah permukaan tanah yang dapat dengan mudah dibaca dan diinterpretasikan oleh user. Signal processing sendiri terdiri dari beberapa tahap yaitu A-Scan yang meliputi perbaikan sinyal dan pendektesian objek satu dimensi, B-Scan untuk pemrosesan data dua dimensi  dan C-Scan untuk pemrosesan data tiga dimensi. Metode yang digunakan pada pemrosesan B-Scan salah satunya adalah dengan  teknik pemrosesan citra. Dengan pemrosesan citra, data survey B-scan diolah untuk didapatkan informasi mengenai objek. Pada penelitian ini, diterapkan teori gradien garis pada pemrosesan citra B-scan untuk menentukan bentuk dua dimensi dari objek bawah tanah yaitu persegi, segitiga atau lingkaran. 

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