Simulation of ground‐penetrating radar waves in a 2-D soil model

Geophysics ◽  
1996 ◽  
Vol 61 (4) ◽  
pp. 1034-1049 ◽  
Author(s):  
David A. Casper ◽  
K ‐J. Samuel Kung
Keyword(s):  
Ground Penetrating Radar ◽  
Flow Simulation ◽  
Absorbing Boundary Conditions ◽  
Absorbing Boundary ◽  
Background Medium ◽  
Soil Model ◽  
Soil Structures ◽  
Homogeneous Background ◽  
Ground Penetrating ◽  
Radar Wave

We have developed a pseudospectral forward modeling algorithm for ground‐penetrating radar (GPR) based on an explicit solution of the 2-D lossy electromagnetic wave equation. Complex soil structures can be accommodated with heterogeneous spatial distributions of both wave velocity and electrical conductivity. This algorithm uses a Gaussian line source with uniform directivity, and there are conductive buffer regions surrounding the soil model to approximate absorbing boundary conditions. Three soil models are used to illustrate different aspects of radar wave propagation. The first model is lossless with homogeneous layers imbedded in a homogeneous background medium, the second model has the same lossless layers in a lossy background medium, and the third model is lossless and uses a nonsaturated water flow simulation to create a complex spatial velocity distribution. Two separate simulations with different source frequencies are presented for each soil model. Results indicate that higher frequency GPR will produce a sharper wavelet and can map soil layering structures with high resolution. In a conductive soil, however, higher frequencies attenuate more rapidly and the radar may not detect deeper layers.

Application of Symplectic Partitioned Runge-Kutta Method and Total-Field Scattered-Field Formulation to Simulation of GPR Data

2014 ◽  
Vol 926-930 ◽  
pp. 2777-2780
Author(s):  
Hong Yuan Fang ◽  
Jian Li ◽  
Jia Li
Keyword(s):  
Scattered Field ◽  
Measured Signal ◽  
Total Field ◽  
Time Step ◽  
Absorbing Boundary ◽  
Runge Kutta Method ◽  
Actual Field ◽  
Ground Penetrating ◽  
Radar Wave ◽  
Difference Time

The second-order Lobatto IIIA-IIIB symplectic partitioned RungeKutta (SPRK) method, combining with the first-order Mur absorbing boundary condition, is developed for the simulation of ground penetrating radar wave propagation in layered pavement structure. For 2-dimetional case, a significant advantage of this method is that only two functions need to be calculated at each time step. The total-field/scattered-field technique is used for plane wave excitation. Numerical examples are presented to verify the accuracy and efficiency of the proposed algorithm. The results illustrate that the reflected signal calculated by the SPRK method is in good agreement with that obtained using the finite difference time domain (FDTD) scheme, but the CPU time consumed by proposed algorithm is reduce about 20% of the FDTD scheme. In addition, an actual field test is conducted to evaluate the further performance of the SPRK method. It is found that the simulated waveform fits well with the measured signal in many aspects, especially in the peak amplitude and time delay.

Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar

2009 ◽  
Vol 40 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Nils Granlund ◽  
Angela Lundberg ◽  
James Feiccabrino ◽  
David Gustafsson
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Laboratory Test ◽  
Liquid Water ◽  
Ground Penetrating Radar ◽  
Wave Attenuation ◽  
Radar Measurements ◽  
Ground Penetrating ◽  
Radar Wave ◽  
The Relationship

Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1 m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.

scholarly journals High-resolution hydrothermal structure of Hansbreen, Spitsbergen, mapped by ground-penetrating radar

1999 ◽  
Vol 45 (151) ◽  
pp. 524-532 ◽  
Author(s):  
J.C. Moore ◽  
A. Pälli ◽  
F. Ludwig ◽  
H. Blatter ◽  
J. Jania ◽  
...  
Keyword(s):  
High Resolution ◽  
Ground Penetrating Radar ◽  
Water Levels ◽  
Large Water ◽  
Complex Temperature ◽  
Polythermal Glacier ◽  
Ground Penetrating ◽  
Isolated Point ◽  
Radar Wave ◽  
Water Contents

AbstractDetailed ground-penetrating radar (GPR) surveys at 50 and 200 MHz on Hansbreen, a polythermal glacier in southern Svalbard, are presented and interpreted. Comparison of the variations in character of the radar reflections with borehole thermometry and water levels in moulins suggests that GPR can be used to study the hydrothermal properties of the glacier. The high resolution of the GPR data shows that the hydrothermal structure of the glacier is highly variable both along the centre line and on transverse profiles. Water contents for many places and depths within the glacier were calculated by estimating radar-wave velocities to point reflectors. We find typical water contents of 1-2% for the temperate ice, but wetter ice associated with surface crevassing and moulins (typically 4% water content). There is evidence that wet ice sometimes overlays drier ice. The hydrothermal structure is thus shown to be very complex. Temperature gradients in the cold ice indicate freezing rates of temperate ice below cold ice of 0.1-0.5 ma-1, while isolated point reflectors within the cold ice indicate large water-filled bodies that are probably related to the regular drainage structure of the glacier.

Experimental forensic scenes for the characterization of ground-penetrating radar wave response

2012 ◽  
Vol 220 (1-3) ◽  
pp. 50-58 ◽  
Author(s):  
Mercedes Solla ◽  
Belén Riveiro ◽  
Marcos X. Álvarez ◽  
Pedro Arias
Keyword(s):  
Ground Penetrating Radar ◽  
Wave Response ◽  
Ground Penetrating ◽  
Radar Wave

scholarly journals High-resolution hydrothermal structure of Hansbreen, Spitsbergen, mapped by ground-penetrating radar

1999 ◽  
Vol 45 (151) ◽  
pp. 524-532 ◽  
Author(s):  
J.C. Moore ◽  
A. Pälli ◽  
F. Ludwig ◽  
H. Blatter ◽  
J. Jania ◽  
...  
Keyword(s):  
High Resolution ◽  
Ground Penetrating Radar ◽  
Water Levels ◽  
Large Water ◽  
Complex Temperature ◽  
Polythermal Glacier ◽  
Ground Penetrating ◽  
Isolated Point ◽  
Radar Wave ◽  
Water Contents

AbstractDetailed ground-penetrating radar (GPR) surveys at 50 and 200 MHz on Hansbreen, a polythermal glacier in southern Svalbard, are presented and interpreted. Comparison of the variations in character of the radar reflections with borehole thermometry and water levels in moulins suggests that GPR can be used to study the hydrothermal properties of the glacier. The high resolution of the GPR data shows that the hydrothermal structure of the glacier is highly variable both along the centre line and on transverse profiles. Water contents for many places and depths within the glacier were calculated by estimating radar-wave velocities to point reflectors. We find typical water contents of 1-2% for the temperate ice, but wetter ice associated with surface crevassing and moulins (typically 4% water content). There is evidence that wet ice sometimes overlays drier ice. The hydrothermal structure is thus shown to be very complex. Temperature gradients in the cold ice indicate freezing rates of temperate ice below cold ice of 0.1-0.5 ma-1, while isolated point reflectors within the cold ice indicate large water-filled bodies that are probably related to the regular drainage structure of the glacier.

Simulation and Experiments on Signals of Ground-Penetrating Radar in Soil Cement

2020 ◽  
pp. 2158003
Author(s):  
Zhezhe Hou ◽  
Yanliang Du
Keyword(s):  
Dielectric Constant ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Soil Layer ◽  
Center Line ◽  
Reflected Waves ◽  
Soil Cement ◽  
Subgrade Soil ◽  
Ground Penetrating ◽  
Radar Wave

Subgrade bedding is a key element of railway structure in stability and durability, and it is almost made of soil cement. The dielectric constant, compaction and curing ages of soil cement with different moisture contents were measured. The relation among curing ages, moisture content, compaction of soil cement and electromagnetic features was analyzed. The model of layered soil cement was established to simulate ground-penetrating radar (GPR) electromagnetic waves in the soil cement. The variation rules of dielectric constant and amplitude of radar signals were obtained. The electromagnetic features, i.e. velocity, frequency and amplitude, were analyzed. Ground-penetrating radar was used to detect the railway subgrade soil layer. Based on the center line of the subgrade, there were nine detection lines for every 1[Formula: see text]m to detect the density and smoothness of the subgrade soil layer. Based on the radar wave events and reflected waves, the subgrade condition can be judged.

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