GPR GPR Applications & Site Assessment 2

Question 1

In a GPR survey for archaeological site assessment, which antenna frequency provides the best balance between resolution and depth penetration for locating buried features at 1–3 meter depths?

Accepted Answer

400–500 MHz

Answer

400–500 MHz antennas offer sufficient resolution to detect archaeological features (walls, pits, artifacts) while achieving the 1–3 m penetration depth typical of archaeological surveys.

Question 2

A GPR survey over a suspected underground storage tank (UST) would most likely show:

Accepted Answer

A flat reflector at the tank depth with a polarity reversal if the tank is air-filled

Answer

An empty UST produces a strong flat reflector with polarity reversal at the metal-air interface, while a fluid-filled tank shows a strong reflector without polarity reversal.

Question 3

When assessing pavement layer thickness with GPR, the operator uses the EM velocity of each layer to convert TWTT to thickness. Which material has the highest EM velocity (lowest dielectric constant) of those listed?

Accepted Answer

Dry concrete

Answer

Dry concrete has a relatively low dielectric constant (~4–6), giving it a higher EM velocity compared to water-saturated or clay materials with much higher dielectric constants.

Question 4

A GPR site assessment for a proposed bored pile installation should include scanning to identify:

Accepted Answer

Existing underground utilities, voids, and obstructions in the bore path

Answer

Pre-bore GPR scanning locates utilities, voids, and obstructions that could be damaged or cause equipment problems during drilling operations.

Question 5

In a GPR survey for rebar mapping in a bridge deck, the primary deliverable to the client typically includes:

Accepted Answer

A scaled plan view showing rebar layout, depth, and any anomalies indicating corrosion or delamination

Answer

Bridge deck GPR reports provide a mapped plan view with rebar depth, spacing, and anomaly locations (low-amplitude zones indicating delamination or corrosion) for maintenance planning.

GPR - Ground Penetrating Radar Specialist Certification Practice Test

GPR - Ground Penetrating Radar Specialist Certification Practice Test

GPR GPR Applications & Site Assessment 2