ground penetrating radar(gpr) ppt

HIGH PERFORMANCE CONCRETE

SDM COLLEGE OF ENGINEERING AND TECHNOLOGY, DHARWAD

CIVIL ENGINEERING DEPT.

Presented byName-MANMOHAN KUMAR USN-2SD12EC040

UNDER THE GUIDENCE OF Mr. C.P.JOSHI (Asst. Prof.)

05/01/2023

Contents Introduction Components of GPR GPR working principle Data Acquisition GPR Technology Data Model and Layer-Stripping Inversion D/T in pavement profiling Multiple-Interface D/T Applications Advantages Limitations Conclusion

4-Mar-16 MULTI TARGET DETECTIONRADAR

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 is used for finding and detecting buried object. GPR have a co-located transmitter and receiver. Ground penetrating radar(GPR) is a short range pulse

system for remote sensing applications. Monostatic GPR operates by transmitting electromagnetic

energy down into the ground through an antenna .

4-Mar-16 MULTI TARGET DETECTION USING RADAR

Components of GPR


1.Transmitting and receiving unit2.Control unit3.Display unit4.Power supplies

Fig no.:-01, Process of GPR[1]

MULTI TARGET DETECTIONRADAR

05/01/2023

Antennae Frequency Maximum Penetration Depth

Examples of Potential Use

1500 MHz 0.5 m Rebar mapping and concrete evaluation.

900 MHz 1 mPipe and void detection or assessing concrete thickness.

400 MHz 4 mUtility surveys, pavement evaluation, storage tank detection and assessing structural integrity.

300 MHz 6m Utility surveys, geology and archaeology.

GPR Working Principle

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MULTI TARGET DETECTION USING RADAR

Fig no.:-02,GPR working principle [2]

Reflected Signal:

The amount of reflected energy at an interface is governed by:

where ρ1,2 is the reflection coefficient and εr1 and εr2 are the dielectric constants.

21

212,1

rr

rr

Typical Dielectric Constants:Material Relative

permittivity Air 1

Asphalt: dry 2-4

Clay 2-40

Dry sand 3-5

Concrete: dry 4-10

Fresh water 80

Metals ∞

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

Data Acquisition


GPR uses high frequency radio waves and transmits into the ground.When the waves hits the buried object or a boundary with different dielectric constants, the receiving antenna records variations in the reflected return signal.The depth range of GPR is limited by electrical conductivity of the ground ,the transmitted frequency and the radiated power. As conductivity increases the penetration depth decreases.

4-Mar-16

MULTI TARGET DETECTION USING RADAR

Fig no.:-03,schematic diagram of a GPR [3]

GPR Technology


Fig no.:-04 ,GPR technology [4]

GPR Technology(cont.)


Air coupled antenna.Ground coupled antenna.

Fig no.:-05,Air coupled antenna[5]

Fig no.:-06,Ground coupled antenna[6]

Data Model and Layer-Stripping Inversion In pavement, each layer of asphalt or concrete is

basically a mixture of particles embedded in an homogenous matrix.

Since particle size is considered to be small if compared to the waveform resolution of the GPR system, each system can be model as a homogeneous medium with effective complex dielectric permittivity values.

Layer-stripping inversion is used to estimate the permittivity profile as well as the location in depth of those interfaces estimated in time.


Detection/Tracking in pavement profiling Layer-stripping inversion with monostatic GPR is rather

complicated since the echo amplitude decreases with time due to waveform attenuation.

Moreover ,the estimate of the echo amplitude is biased due to propagation through random media.

Consequently, in pavement profiling, the SNR decreases with depth.


Multiple-Interface D/T

In the presence of more than one interface, the multimode and the D/T components tracks the echo delay with the largest SNR.

In principle, this tracking ambiguity could be avoided by processing subsequence of time samples.

In practice, errors are difficult to avoid when two interfaces are close to each other (because of limits in echo resolution), when one interface splits into two interfaces, or even when two or more interfaces merge into one.


Application


In the Earth sciences it is used to study bedrock, soils, groundwater and ice.

Military uses including detection of mines, unexploded ordnance detection, and tunnels.

Locating clandestine graves and buried evidence. The other main applications is to locate underground

utilities.

Advantages


Low cost Extremely accurate Fast Not needed to drilling and digging selected area Real time targeting Non-destructive Digital media storage Easy to operate Safe

Site specifics. Limitations if dielectric properties are similar. Difficult in thin layer. Compromise between penetration depths and target

resolutions. Requires fairly uniform soil for moisture estimation.


Limitations

References

1. D. J. Daniels, D. J. Gunton, and H. F. Scott, “Introduction to subsurface radar,” Proc. Inst. Elect. Eng. F, vol. 135, pp. 278–320, Aug. 1988.

2. U. Spagnolini, “Permittivity measurements of multilayered media with monostatic pulse radar,” IEEE Trans. Geosci. Remote Sensing, vol. 35, pp. 454–463, Mar. 1997.

3. S. S. Blackman, Multiple-Target Tracking with Radar Applications. Dedham, MA: Artech House, 1986.

4. http://Wikipedia.com/5. http://books.google.com/


http://wikipedia.com/

http://books.google.com/

Thank YOU


ground penetrating radar(gpr) ppt

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