Gpr seminar by emmaual
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Seminar presentation on “GROUND PENETRATING RADAR” SYSTEM DESIGN &PROCESSING EMMANUAL ROY MSc. APPLIED GEOPHYSI M S UNIVERSITY
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Transcript of Gpr seminar by emmaual
Seminar presentation on
“GROUND PENETRATING RADAR”
SYSTEM DESIGN &PROCESSING
EMMANUAL ROYMSc. APPLIED GEOPHYSICSM S UNIVERSITY
Introduction: RADAR → Radio Detection and Ranging.
◦ Detect target in free space◦ Determine the range
Ground-penetrating radar (GPR) is a geophysical method that uses radar pulses to image the subsurface.
◦ GPR finding and detecting buried object. 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.
◦ Probing into soil to detect pipelines and tanks and detect thickness of soil layers in sub surface.
◦ The GPR is the safest and easiest method of analyzing and surveying any area. The readings and services of the ground penetrating radar equipment are accurate. It is the best and most effective method to survey any underground project.
GPR Working Principle:An EM pulse is sent
through an antenna, penetrating into the surveyed material.
A portion of the energy is reflected back to the antenna when an interface between materials of dissimilar dielectric constant is encountered.
System designIt has a microprocessor based
electronic sectionMicrowave sectionThe electronic section controls
it’s operations to acquire data and processing to display
Heart of GPR is microwave section contains
Receiver and Transmitter Antennas which controls the size and ability of the entire system
Components of GPR:
1. Transmitting and receiving unit
2. Control unit3. Display unit4. Power
supplies
Block diagram
BLOCK DIAGRAM
Ground-Coupled Antennas
1.5 GHz 500 MHz
Processing
The ground penetrating radar equipment emits high frequency radar waves that would penetrate the ground several feet below. These microwaves will then bounce back on to the GPR equipment's receiver.
It will provide information about the depth and density of what lies beneath the ground. The technicians who specialize in the subject are capable of creating a detailed map of what lies under the surface of the ground.
How deep can GPR go into ground?:It depend upon two
condition: The type of soil or rock in
the GPR survey area. The frequency of the
antenna used.Low frequency systems are
more penetrating but data resolution is lower.
High frequency systems have limited penetration but offer a much higher resolution.
Antenna Frequency
Maximum Penetration
Depth
Appropriate Application
1500 MHz 0.5 mRebar mapping and concrete evaluation.
900 MHz 1 mPipe and void detection or assessing concrete thickness.
400 MHz 4 m
Utility surveys, pavement evaluation, storage tank detection and assessing structural integrity
270 MHz 6mUtility surveys, geology and archaeology
GPR Depth Determination:The reflected signal
has information on:◦how quickly
the signal traveled◦how much was
attenuatedThese quantities
depend on spatial configuration and materials.
The depth of a layer is given by:
D = (5.9t)/sqrt. of(Er)D = depth of target (inch.)
t = wave travel time (nanosecond)
5.9 = a constant incorporating speed of light and unit conversions
Er = dielectric constant of subsurface material
Advantages:
Extremely accurateFastNot needed to drilling and digging selected areaReal time targetingNon-destructiveNon-intrusiveDigital media storageEasy to operate Safe
Applications:
In the Earth sciences it is used to study bedrock, soils, groundwater, and ice.
Military uses include detection of mines, unexploded ordnance, and tunnels.
Locating clandestine graves and buried evidence.
The other main applications for ground penetration radars to locate underground utilities.
