The fifth China-Japan Joint Seminar for the Graduate Students in Civil Engineering
AN OVERVIEW ON THE TECHNOLOGY OF HIGH
SPEED AND NON-DESTRUCTIVE INSPECTION
OF HIGHWAY TUNNEL LINING DEFECTS
H. Liu, X. R. Liu & X. Y. Xie
Geotechnical Department of Tongji University, Shanghai, China
OUTLINE
1
Introduction & Requirements
2
Existing Techniques Examined
3
Methods Suitable for the Topic
4
Conclusions & Outlook
1
INTRODUCTION & REQUIREMENTS
1
Introduction
Mountain highway tunnels suffer from great external rock pressure,
seismic load, and concrete deterioration. Furthermore, differing from onground structures, their design conditions vary case by case. So it is
common to find deformation, severe leakage, big cavities, cracks and
other lining defects after the tunnels are put into usage.
Rock
pressure
Seismic Concrete
load deterioration
Varying design condition
Mountain Highway Tunnel
Deformation Leakage
Cavities
Cracks
1
Introduction
1
Introduction
How to detect all these lining defects
Manual methods
geophysical surveys
Slow
fast
destructive
Non-destructive
imprecise
What are requirements
accurate
1
Requirements
The aim of non-destructive testing methods is to obtain complete, reliable
and reproducible data on the state of the entire highway tunnel lining.
Requirements
1
Essentially non-destructive
2
Examination at any point
3
Used in different tunnels
4
Not be influenced by
installations
5
High traveling speed
6
Resistant to vibrations and
operate in different climate
7
Established accurate
defective zones
8
Results should be
available immediately
2
Existing Techniques Examined
2
1
Mechanical Oscillation Techniques
Structural dynamic
methods
Seismic reflection
and refraction
2
Existing Techniques Examined
Measuring the response
to an artificially
induced vibration
Microseismics and sonic
emission analysis
Ultrasonics--reflection and
indirect surface transmission
Radiation Techniques
gamma ray
backscatter
neutron
backscatter
determine the density
and moisture content
2
3
Electric and Electronic Techniques
eddy current
methods
4
Existing Techniques Examined
ground penetrating
radar
electrical potential
methods
Optical Techniques
infrared
thermograph
Multi-spectral
analysis
CCD digital
camera
2
Existing Techniques Examined
Discussion
Advantages and disadvantages of various techniques
Techniques
Main Application
Value
Structural dynamic
methods (direct vibration)
Bridges;
Aboveground
buildings
Seismic reflection
Geological
investigations;
determination of
layer thickness
Low
Micro-seismics and
sonic Emission
analysis
Coal mines;
laboratory tests
Very low
UItrasonios-reflection and
indirect surface
transmission
Steal construction;
Mechanical engineering;
pipelines; tanks
Gamma ray
backscatter
Road construction,
Earth construction;
investigation of
moisture content
and density
Mechanical
Oscillation
Techniques
Radiation
Techniques
Neutron backscatter
Very
low
Problems With
Uneven wall
thickness; rock
in homogeneity;
varying ground
water level
Accuracy; speed
Reproducibility; accuracy
Advantages
None
Only connected with
very large cavities
behind
the tunnel
lining
Investigation of
structure-bome noise
Very low
Coupling to test
ground, concrete
inhomogeneity; speed of
diffusion by aggregates;
accuracy
None
Very low
Speed;
penetration depth
None
Low
Speed,
penetration, depth
Indication of
moisture content
point-by-point
2
Existing Techniques Examined
Advantages and disadvantages of various techniques
Techniques
Electric and
Electronic
Techniques
Optical
Techniques
Main Application
Value
Problems With
Advantages
Eddy current
methods
Electricity conducting metals;
crack detecting for
pipelines, indication of
reinforcement
Low
Speed,
non-conducting materials;
penetration depth.
Indication of
reinforcement
Georadar
Ground investigation of bridges
and
tunnels
High
Evaluation; reflection by
metallic cladding;
speed
Good penetration
depth
Electrical potential
methods
Detection of
corrosion of
reinforcement
Low
Speed; penetration depth
Detection of
corrosion
Infrared thermography
combined with
visual determination
Check of thermal
insulation; tunnels
Very
high
Certain tunnel
climates; evaluation; heat
release of
installations
Detection of
cavities and
moist patches,
cracks, etc.; high speed
CCD digital
cameral
Inspection of
structure surface
high
Illuminator; Measurement
algorithm
Detection of
cracks; High
speed
Georadar
Infrared thermography
CCD digital
cameral
3
Methods Suitable for the Topic
3
Ground penetrating radar (GPR)
CCD digital camera
Infrared topography
Methods Suitable for the Topic
3
Methods Suitable for the Topic
GPR
Operating principle: used in reflection mode.
high-frequency
electromagnetic wave
emitting antenna
receiving antenna
interfaces
the reinforcing steel bar
defects in the lining
GPR has been popularly used
to detect the tunnel lining, and
it can detect the crack, leakage
and cavities behind the lining.
3
Methods Suitable for the Topic
CCD Camera
CCD Camera is widely used for the inspection of structural surfaces,
especially the crack detection of tunnel lining.
Operating principle:
Power supply
Illuminator
Tunnel
Optical device
CCD Camera
Image processing system
Image analysis system
Crack map
Image acquisition system
Information
of crack
Data storage
3
Methods Suitable for the Topic
Infrared topography
Operating principle: Infrared topography makes use of thermal
radiation, which is radiated by every surface.
A thermal flow can be created through a current of gaseous
material or a liquid material. Points affected by such thermal flows
are generally characterized by a pronounced increase or decrease
in temperature, in comparison with their surroundings.
In this way, possible damage in the tunnel lining can be determined
through the use of infrared topography.
moist
patches
mainly
Identify
water
seepage
4
Conclusions & Outlook
4
Conclusions & Outlook
GPR
Cracks and cavities
behind the lining
CCD camera
Defects (crack) on the
surface of the lining
Infrared topography
moist patches
water seepage
integrated
inspection car
Thank you!