Geoscience Reference
In-Depth Information
7
Ground-Penetrating
Radar Methods (GPR)
Jeffrey Daniels, M. Reza Ehsani, and Barry J. Allred
ContentS
7.1
Introduction ......................................................................................................................... 129
7.2
Basic Principles ................................................................................................................... 130
7.2.1 Propagation and Scattering ...................................................................................... 130
7.2.2 GPR Recording ........................................................................................................ 132
7.2.3 Polarization .............................................................................................................. 133
7.2.4 Velocity .................................................................................................................... 134
7.3
Equipment ........................................................................................................................... 134
7.3.1
System Overview ..................................................................................................... 134
7.3.2
A nt en na s .................................................................................................................. 135
7.4
Field Operations .................................................................................................................. 137
7.4.1 Field Procedures ...................................................................................................... 137
7.4.1.1 Station and Trace Spacing .......................................................................... 138
7.4.1.2 Depth of Penetration................................................................................... 138
7.4.1.3 Antenna Frequency .................................................................................... 138
7.4.2 Filtering and Amplification...................................................................................... 139
7.4.3 Static Corrections..................................................................................................... 139
7.4.4 Velocity Analysis and Two-Dimensional Filtering.................................................. 139
7.5
Display and Interpretation................................................................................................... 142
7.5.1 Display Processing................................................................................................... 142
7.5.1.1 Two-Dimensional Displays ........................................................................ 142
7.5.1.2 Three-Dimensional Displays...................................................................... 143
7.5.2 Interpretation............................................................................................................ 145
7.1 IntRodUCtIon
Ground-penetrating radar (commonly called GPR) is a high-resolution electromagnetic technique
designed primarily to investigate the shallow subsurface of the earth, building materials, and roads
and bridges. GPR has been developed over the past thirty years for shallow, high-resolution investi-
gations of the subsurface. GPR is a time-dependent geophysical technique that can provide a three-
dimensional pseudo-image of the subsurface, including the fourth dimension of color, and can also
provide accurate depth estimates for many common subsurface objects. Under favorable conditions,
GPR can provide precise information concerning the nature of buried objects. It has also proven
to be a tool that can be operated in boreholes to extend the range of investigations away from the
boundary of the hole.
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