scholarly journals Spatially Extensive Ground‐Penetrating Radar Snow Depth Observations During NASA's 2017 SnowEx Campaign: Comparison With In Situ, Airborne, and Satellite Observations

2019 ◽  
Vol 55 (11) ◽  
pp. 10026-10036 ◽  
Author(s):  
Daniel McGrath ◽  
Ryan Webb ◽  
David Shean ◽  
Randall Bonnell ◽  
Hans‐Peter Marshall ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Snow Depth ◽  
Satellite Observations ◽  
Ground Penetrating

scholarly journals Identifying Spatial and Temporal Variations in Concrete Bridges with Ground Penetrating Radar Attributes

2021 ◽  
Vol 13 (9) ◽  
pp. 1846
Author(s):  
Vivek Kumar ◽  
Isabel M. Morris ◽  
Santiago A. Lopez ◽  
Branko Glisic
Keyword(s):  
Compressive Strength ◽  
Ground Penetrating Radar ◽  
Material Properties ◽  
Temporal Variations ◽  
Concrete Bridges ◽  
Spatial And Temporal Variation ◽  
Reflected Waves ◽  
Ground Penetrating ◽  
Over Time

Estimating variations in material properties over space and time is essential for the purposes of structural health monitoring (SHM), mandated inspection, and insurance of civil infrastructure. Properties such as compressive strength evolve over time and are reflective of the overall condition of the aging infrastructure. Concrete structures pose an additional challenge due to the inherent spatial variability of material properties over large length scales. In recent years, nondestructive approaches such as rebound hammer and ultrasonic velocity have been used to determine the in situ material properties of concrete with a focus on the compressive strength. However, these methods require personnel expertise, careful data collection, and high investment. This paper presents a novel approach using ground penetrating radar (GPR) to estimate the variability of in situ material properties over time and space for assessment of concrete bridges. The results show that attributes (or features) of the GPR data such as raw average amplitudes can be used to identify differences in compressive strength across the deck of a concrete bridge. Attributes such as instantaneous amplitudes and intensity of reflected waves are useful in predicting the material properties such as compressive strength, porosity, and density. For compressive strength, one alternative approach of the Maturity Index (MI) was used to estimate the present values and compare with GPR estimated values. The results show that GPR attributes could be successfully used for identifying spatial and temporal variation of concrete properties. Finally, discussions are presented regarding their suitability and limitations for field applications.

IN-SITU CASSAVA ROOT SIZE MEASUREMENT USING GROUND PENETRATING RADAR (GPR)

2018 ◽  
Author(s):  
Timothy H. Larson ◽  
Riley J. Balikian ◽  
Ursula Ruiz-Vera ◽  
Donald Ort
Keyword(s):  
Ground Penetrating Radar ◽  
Size Measurement ◽  
Cassava Root ◽  
Ground Penetrating ◽  
Root Size

scholarly journals Accounting for Surface Roughness Scattering in the Characterization of Forest Litter with Ground-Penetrating Radar

2019 ◽  
Vol 11 (7) ◽  
pp. 828
Author(s):  
Frédéric André ◽  
François Jonard ◽  
Mathieu Jonard ◽  
Harry Vereecken ◽  
Sébastien Lambot
Keyword(s):  
Surface Roughness ◽  
Ground Penetrating Radar ◽  
Land Surface ◽  
Forest Litter ◽  
Relative Dielectric Permittivity ◽  
In Situ Experiment ◽  
In Situ Experiments ◽  
Ground Penetrating

Accurate characterization of forest litter is of high interest for land surface modeling and for interpreting remote sensing observations over forested areas. Due to the large spatial heterogeneity of forest litter, scattering from litter layers has to be considered when sensed using microwave techniques. Here, we apply a full-waveform radar model combined with a surface roughness model to ultrawideband ground-penetrating radar (GPR) data acquired above forest litter during controlled and in situ experiments. For both experiments, the proposed modeling approach successfully described the radar data, with improvements compared to a previous study in which roughness was not directly accounted for. Inversion of the GPR data also provided reliable estimates of the relative dielectric permittivity of the recently fallen litter (OL layer) and of the fragmented litter in partial decomposition (OF layer) with, respectively, averaged values of 1.35 and 3.8 for the controlled experiment and of 3.9 and 7.5 for the in situ experiment. These results show the promising potentialities of GPR for efficient and non-invasive characterization of forest organic layers.

GPR attenuation and its numerical simulation in 2.5 dimensions

Geophysics ◽  
1997 ◽  
Vol 62 (2) ◽  
pp. 403-414 ◽  
Author(s):  
Tong Xu ◽  
George A. McMechan
Keyword(s):  
Time Domain ◽  
Ground Penetrating Radar ◽  
Finite Difference Time Domain ◽  
Superposition Method ◽  
Frequency Data ◽  
Buried Pipe ◽  
Ground Penetrating ◽  
Cole Model ◽  
Difference Time

Modeling of ground‐penetrating radar (GPR) data in 2.5 dimensions is implemented by superposition of 2-D finite‐difference, time‐domain solutions of Maxwell's equations for different horizontal wavenumbers. Dielectric, magnetic, and conductive losses are included in a single formulation. Attenuations associated with dielectric and magnetic relaxations are introduced by superposition of Debye functions at a set of relaxation frequencies and using memory variables to replace convolutions between the field variables and the decay functions. Better fits to data may always be obtained using the superposition method than by the Cole‐Cole model. Good fits to both loss‐tangent versus frequency data from lab measurements, and to 500 and 900 MHz field GPR profiles of a buried pipe and the surrounding layers, demonstrate the flexibility and viability of the modeling algorithm. Discrepancies between lab and in‐situ measurements may be attributed to scale differences and local variations that make lab samples less representative of the site than the GPR profile.

Research on Combined Tests to Entry Disturbed Zone (EDZ) of Rock Masses in Steep Coal Seams

2013 ◽  
Vol 718-720 ◽  
pp. 842-847
Author(s):  
Peng Fei Shan ◽  
Xing Ping Lai ◽  
Jian Tao Cao ◽  
Lin Yao Li
Keyword(s):  
Rock Mass ◽  
Ground Penetrating Radar ◽  
Rock Masses ◽  
East Side ◽  
Coal Seams ◽  
Disturbed Zone ◽  
Explosive Wave ◽  
High Production ◽  
Ground Penetrating

For high production of raw coal in steep coal seams, it is crucial to obtain engineer demands by enhancing section height in horizontal caving. However in-situ operations copious methods like pre-blasting was always needed to broken top-coal which was difficult to excavate commodiously and safely. Explosive wave caused by pre-blasting would destroy stress balance around entries, and definitely result in entry disturbed zone (EDZ) being loosen zone. Aimed to determine boundary of EDZ and keep rock mass in both entries steady, combined tests to EDZ of rock masses of head entry of +600 east-side stope of 43# coal seam was done in Wudong Colliery as research background with ground penetrating radar (GPR) and mono-hole ultrasonic wave experiment. It indicated that scope of EDZ here was 2.2-2.3m, which would be prerequisite to optimize supporting scheme in field.

In Situ Root Volume Estimation Using Ground Penetrating Radar

2017 ◽  
Vol 22 (3) ◽  
pp. 209-221 ◽  
Author(s):  
Janet E. Simms ◽  
S. Kyle McKay ◽  
Robert W. McComas ◽  
J. Craig Fischenich
Keyword(s):  
Ground Penetrating Radar ◽  
Volume Estimation ◽  
Root Volume ◽  
Ground Penetrating

Velocity estimation by the common-reflection-surface (CRS) method: Using ground-penetrating radar data

Geophysics ◽  
2005 ◽  
Vol 70 (6) ◽  
pp. B43-B52 ◽  
Author(s):  
Hervé Perroud ◽  
Martin Tygel
Keyword(s):  
Ground Penetrating Radar ◽  
Radar Data ◽  
Velocity Estimation ◽  
Agricultural Activities ◽  
Water Conductivity ◽  
Common Reflection Surface ◽  
The Common ◽  
The Time Domain ◽  
Ground Penetrating

In this paper, we describe the use of the common-reflection-surface (CRS) method to estimate velocities from ground-penetrating radar (GPR) data. Applied to multicoverage data, the CRS method provides, as one of its outputs, the time-domain rms velocity map, which is then converted to depth by the familiar Dix algorithm. Combination of the obtained depth-converted velocity map with electrical resistivity in-situ measurements enables us to estimate both water content and water conductivity. These quantities are essential to delineate infiltration of contaminants from the surface after industrial or agricultural activities. The method was applied to GPR data and compared with the classical NMO approach. The results show that the CRS method provides a physically more meaningful velocity field, thus improving the potential of GPR as an investigation tool for environmental studies.

scholarly journals Wet subglacial bedforms of the NE Greenland Ice Stream shear margins

2019 ◽  
Vol 60 (80) ◽  
pp. 91-99 ◽  
Author(s):  
Kiya L. Riverman ◽  
Sridhar Anandakrishnan ◽  
Richard B. Alley ◽  
Nicholas Holschuh ◽  
Christine F. Dow ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Acoustic Impedance ◽  
Impedance Analysis ◽  
Flow Conditions ◽  
Lateral Shear ◽  
Ice Flow ◽  
Ice Stream ◽  
Water Saturated ◽  
Ground Penetrating

AbstractWe describe elongate, wet, subglacial bedforms in the shear margins of the NE Greenland Ice Stream and place some constraints on their formation. Lateral shear margin moraines have been observed across the previously glaciated landscape, but little is known about the ice-flow conditions necessary to form these bedforms. Here we describe in situ sediment bedforms under the NE Greenland Ice Stream shear margins that are observed in active-source seismic and ground-penetrating radar surveys. We find bedforms in the shear margins that are ~500 m wide, ~50 m tall, and elongated nearly parallel to ice-flow, including what we believe to be the first subglacial observation of a shear margin moraine. Acoustic impedance analysis of the bedforms shows that they are composed of unconsolidated, deformable, water-saturated till. We use these geophysical observations to place constraints on the possible formation mechanism of these subglacial features.

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