GROUND PENETRATING RADAR

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• GROUND PENETRATING RADAR
• (GPR)

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What is GPR you ask?

• A radar system used to investigate subsurface
  areas allowing it to detect buried objects

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How Does it Work?

• Simply put, GPR uses radiowaves to penetrate the
  ground
• It can be employed from the service by hand or
  vehicle, in or between boreholes, from aircraft,
  or satellites.

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Current UsesDetect buried objects and artifacts
such as

• Mines
• Unexploded Ordinance
• Hazardous Waste Containers
• Utility Pipes
• Sinkholes
• Tank and Drum location
• Landfill and Burial Trenches
• Cemetary and Grave sites
• Archaeological Studies

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Newly Discovered Uses

• Civil Infrastructure Systems
• Detecting cracks and voids in bridges, dams,
  pavement and other similar structures
• The traditional method used to detect
  delamination (deterioration caused by the
  corrosion of embedded steel reinforcements) in
  bridges, is the chain drag method. A chain is
  dragged across the bridge deck while a trained
  technician listens for specific differences in
  pitch
• GPR transmits a short-duration pulse (1
  nanosecond or less) into the ground and records
  the reflected waveform. Stable and delaminated
  concrete have their own signature.

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Newly Discovered Uses cont.

• Railroad track substructure monitoring such as
  thickness of ballast, subballast, and subgrade
  layers and detection of water pockets, slurry,
  and other foreign objects help to increase track
  performance
• Tested frequencies were 100 MHZ and 400 MHZ. The
  100 MHZ frequency was found to better detect
  anomalies such as water pockets, where as the 400
  MHZ frequency was more suitable for detecting the
  condition of ties near the surface of the rail
  bed.

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The Future of GPR

• GPR is also being tested to detect buried shallow
  objects with high depth resolution

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GPR is a Method of Choice for a Few Reasons

• The surveys are comparably low-cost
• Can be conducted anywhere in the world
• Near real-time interpretation
• Many available applications
• Non destructive

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In Conclusion

• Compared to the Advantages, the disadvantages
  (general shallow depth of observation and site
  specific applications) do not give reason to
  dismiss the use of Ground Penetrating Radar to
  study objects that are not apparent to the human
  eye.