The document discusses ground penetrating radar (GPR), which uses radar pulses to image the subsurface. It explains that GPR can detect objects, material changes, and voids underground. The document then covers GPR principles, data acquisition, analysis, and applications in civil engineering projects like assessing bridge decks, detecting subsidence, and locating cultural artifacts. Examples of current GPR research, equipment, and software are also presented.

1. Ground Penetrating Radar
Basic for Civil Engineering
2014. 04. 17
GPR Basic for Master’s Course
Jiyoung Rhee
Engineer Researcher

3. What is RADAR?
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4. RADAR?
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5. RADAR? No! Laser
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6. RADAR
Surveillance(Search) Radar (Army/Aiport)
http:// www.naval-technology.com
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7. RADAR
Weather Radar
http://www.kma.go.kr/
7/45

8. RADAR
3 Dimensional Radar(TRMM PR)
[Hurricane Sandy, Oct. 28, 2012 at 1725 UTC (1:25 PM EDT)]http://trmm.gsfc.nasa.gov/ 8/45

9. RADAR
Navigation
http://www.nauticexpo.com/
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10. RADAR
• Radio Detecting And Ranging
• An object-detection system that
uses radio waves to determine the
range, altitude, direction, or speed of
objects.
http://en.wikipedia.org/
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11. RADAR
http://en.wikipedia.org/
Principle of a Sonar or Radar Distance Measurement
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12. G P R ?
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13. Ground
Penetrating
Radar
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14. Ground Penetrating Radar
• A geophysical method that
uses radar pulses to image the
subsurface.
• This nondestructive method detects
the reflected signals from subsurface
structures.
http://en.wikipedia.org/
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15. Ground Penetrating Radar
• GPR can be used in a variety of
media, including rock, soil, ice, fresh
water, pavements and structures.
• It can detect objects, changes in
material, and voids and cracks.
http://en.wikipedia.org/
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16. Ground Penetrating Radar
Deterioration
Approach
Thickness
Pavement
Sink hole
Rebar
Tunnel
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17. Definitions!
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18. Dielectric Constant
• Dielectric Permittivity is the property that
describes the ability of a material to store
electric energy by separating opposite
polarity charges in space. (units :
farads/metre(F/m))
• Relative dielectric permittivity (dielectric
constant) is the ratio of the permittivity of a
material to that of free space, 8.854×10−12
F/m. (No unit!)
ASTM D 6432 – 11 3.2.9
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19. Electrical Conductivity
• The ability of a material to support an
electrical current (material property that
describes the movement of electrons or
ions) due to an applied electrical field.
(units : Siemens/metre (S/m)).
ASTM D 6432 – 11 3.2.5
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20. Electrical Properties
Approximate Electromagnetic Properties of Various Materials
ASTM D 6432 – 11 Table 1
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21. Survey & Analysis
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22. Data Acquisition
ASTM D 6432 – 11 Fig 1.
Schematic Diagram of a Ground-Penetrating Radar System
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23. Data Acquisition
• GPR uses high-frequency radio waves
and transmits into the ground.
• When the wave hits a buried object or a
boundary with different dielectric
constants, the receiving antenna
records variations in the reflected return
signal.
http://en.wikipedia.org/
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24. Data Acquisition
• The depth range of GPR is limited by
the electrical conductivity of the ground,
the transmitted center frequency and the
radiated power.
• As conductivity increases, the penetration
depth decreases.
• Higher frequencies do not penetrate as far
as lower frequencies, but give better
resolution.
http://en.wikipedia.org/
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25. Data Acquisition
ASTM D 6432 – 11 Fig 1.
Schematic Diagram of a Ground-Penetrating Radar System
Soil
Buried Object
Bed Rock
Transmitter
Antenna
Receiver
Antenna
Control
Unit
Data
Display
Data
Storage
Ground Surface
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26. Data Acquisition
ASTM D 6432 – 11 Fig 1.
Schematic Diagram of a Ground-Penetrating Radar System
Soil
Buried Object
Bed Rock
Transmitter
Antenna
Receiver
Antenna
Control
Unit
Data
Display
Data
Storage
Ground Surface
t1
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27. Data Acquisition
ASTM D 6432 – 11 Fig 1.
Schematic Diagram of a Ground-Penetrating Radar System
Soil
Buried Object
Bed Rock
Transmitter
Antenna
Receiver
Antenna
Control
Unit
Data
Display
Data
Storage
Ground Surface
Different
EM Properties
t1 t2
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28. Data Acquisition
ASTM D 6432 – 11 Fig 1.
Schematic Diagram of a Ground-Penetrating Radar System
Soil
Buried Object
Bed Rock
Transmitter
Antenna
Receiver
Antenna
Control
Unit
Data
Display
Data
Storage
Ground Surface
Different
EM Properties
t1 t2
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29. Received Data
ASTM D 6432 – 11 Fig 1.
Soil
Buried Object
Bed Rock
Transmitter
Antenna
Receiver
Antenna
Control
Unit
Data
Display
Data
Storage
Ground Surface
t1 t2
A1
A2
A Trace
+-
Time
A1
A2
Volts
t=t1+t2
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30. Data Analysis
• Depth
ASTM D 6432 – 11 Eq. (1)
m
V
t
d
2
r
m
c
V
- c = propagation velocity in free space(3X108m/s)
- Vm = propagation velocity through the material
- εr = relative permittivity
A Trace
+-
Time
A1
A2
Volts
t=t1+t2
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31. GPR Survey & Analysis
A Series of Traces
Depth
1 2 3 4 5
Survey
Time
1 2 3 4 5
Survey
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Point Reflector

32. GPR Survey & Analysis
A Series of Traces
Depth
1 2 3 4 5
Survey
Time
1 2 3 4 5
Survey
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Line Reflector

33. GPR Survey & Analysis
Wiggle Trace Linescans
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34. Investigation
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35. Rebars in a Concrete Pavement
Linescans Wiggle Trace
Surface
Rebars
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36. Layer Thickness at Bridge Deck
A/C
Rebars
Bottom
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37. Subsidence near the Dongtan IC
Patching
Subsidence
B=1.2m
Grouting
Patching
Grouting
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38. Cultural Treasure in Gyeongju
http://news.dongascience.com/PHP/NewsView.php?kisaid=20120810200002327242
Gyeongju Wolseon, Gyeongsangbuk-do
Seokbinggo
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39. Press News
http://www.yonhapnews.co.kr http://www.e2news.com
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40. Press News
http://www.joins.com http://www.segye.com
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41. Now & the Future?
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42. Now : Research
2012 GPR Conference 42/45

43. Now : Equipment
2012 GPR Conference
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44. Now : Software
2012 GPR Conference
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45. The Future
http://cait.rutgers.edu
The Robot for Bridge Deck Assessment
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46. Question?
Jiyoung Rhee
Mobile : 031-371-2761
Mailto : need@ex.co.kr
http://www.slideshare.net/ssuser6b53da