Transcript URS - Főlap

Application of ground penetrating radar (GPR) in
pavement investigation
Istvan Sereg
Geophysics Technician
URS Infrastructure & Environment UK Limited
Meeting of Young Geoscientists - Tatabanya, Hungary
March 30-31, 2012
Contents
• Introduction
• Reasons & Goals
• GPR-Survey methodology
• Sitework
• High-Speed GPR Survey vs. Slow-Speed GPR Survey
• Office work
• Processing steps
• Advantages & Limitations
• Additional tests
• NDT tests
• DT tests
• Results
• References
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
2
Introduction
3
Introduction
• GPR basics
• Permittivity – Velocity of wave propagation
• Conductivity - Attenuation
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
4
Introduction
• Reasons
• Maintanence work due to pavement failure
•
Cracking: reflective cracks, alligator cracks, thermal cracks, block cracks, linear craks, edge cracks, slippage;
•
Distortion: rutting, shoving or corrugations;
•
Disintegration: raveling/weathering, delamination, potholes;
•
Surface defects: bleeding or flushed asphalt, polished aggregate
• Upgrading
• Goals
• Provide information to engineers undertaking pavement rehabilitation projects,
such as:
• Structure information
• Layer thickness
• Location of changes of construction
• Presence of moisture
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
5
Introduction
NSWP - Near Side Wheel Path
OSWP - Off-Side Wheel Path
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
6
GPR-Survey methodology
7
GPR-Survey methodology
• Sitework
• Planning and optimising geophysical investigation.
• Performing sitework.
OSWP
NSWP
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
8
GPR-Survey methodology
High-Speed GPR Survey
Slow-Speed GPR Survey
• Advantages
• Advantages
• Ground-coupled antennae can be
used
• Fast datacollection
• Possible progression with the
trafficflow
• Disadvantages
• Good lateral resolution
• Disadvantages
• Poor lateral resolution
• TM cooperation needed due to
avoiding H&S issues
• Only air-lunched antennae can be
used
• Prohibited trafficflow
• Slow datacollection
Used for taking longitudinal and/or
Used for taking longitudinal profiles.
transverse profiles.
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
9
GPR-Survey methodology
• Office work
• Data relocation! (referencing to marker posts, HAPMS, site chainage)
• Data processing
RAW DATA
PROCESSED DATA
• Core calibration
• Interpretation (thickness plots, apparent moisture plots)
• Reporting
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
10
GPR-Survey methodology
• Cores
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
11
Advantages & Limitations
Antennae
freqency
Velocity
[mns-1]
Max. penetration
c. [m]
Wavelength
[m]
Min. detectable
object (resolution)
900 MHz
0.1 mns-1
1m
0.11 m
0.035 m – 0.055 m
1 GHz (air
coupl.)
0.1 mns-1
0.6 m
0.1 m
0.03 m – 0.05 m
1.5 Ghz
0.1 mns-1
0.5 m
0.07 m
0.025 m – 0.045 m
Accurancy up to:
90-95%
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
12
GPR-Survey methodology
• High-speed example – recent activity
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
13
GPR-Survey methodology
• Slow-speed example
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
14
GPR-Survey methodology
• High-speed example
Raw GPR data
Processed GPR data
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
15
GPR-Survey methodology
• High-speed example
Picked GPR data
Interpreted thickness plot
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
16
GPR-Survey methodology
• Slow-speed example
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
17
Additional tests
18
Additional tests
• NDT
• FWD
• Visual evaluation
• DT
• Coring
• Laboratory tests
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
19
Results
20
Results of the GPR survey
• High-speed example
Raw GPR data
Interpreted plot
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
21
Results
• Complex and detailed information (Final report) about the road structure
• Material thickness profile
• Apparent moisture content
• Mechanical properties (stiffness, compression strength)
• Pavement life
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
22
References
23
References
• C. Blades, E. Kearney: Asphalt Paving Principles, CLRP#04-3, March, 2004
• W. Muller: Application of ground penetrating radar to road pavement
rehabilitation, Queenslands Roads Edition No 7, 7 March, 2009
• L. Liu: GPR for fast pavement assessment, JHR 07-310, May, 2007
• I. Sereg: Application of ground penetrating radar (GPR) in characterization of
concrete and building structures, Meeting of Young Geoscientists – 25th-26th
March, 2011. Győr, Hungary
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
24
Thank you for your attention!
[email protected]
Thank you for your attention!
Application of
Ground Penetrating Radar in pavement investigation
Presentation
Title
Meeting of Youndg Geoscientists – Tatabanya, Hungary – March 30-31, 2012
25