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Phd in Seismic Enginnering and structural dynamics

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Sónia Santos Assunção

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Transcript of Phd in Seismic Enginnering and structural dynamics

1. Development and improvement
of the
radar data processing
methodology.


2.
Laboratory experiments
and
numerical
simulations
- under controlled conditions.


3. Development and application of the new methodologies to
shallow geology
, in
urban
areas and
rural
areas.

4. Development and application of the new methodologies to structures and elements in
buildings
with (non uniform)
complex geometries
with distinct materials in
low
and
high seismic risk zones.
PhD in seismic engineering and structural dynamics
Sónia Alexandra Santos Assunção
Director: Maria Vega Pérez-Gracia
Co-Director: José Ramon González-Drigo
GROUND PENETRATING RADAR APPLICATIONS IN SEISMIC ZONATION: ASSESSMENT AND EVALUATION
Barcelona, 21st November 2014
Objectives
6. Development of programs

GPR - General

State of the Art
Low activity seismic zone - urban
geology
1. Study of the shallow geology of Barcelona
1.1 Locate the paleochannels.
1.2 Locate underground streams.
1.3 Compare GPR with H/V and maps.
1.4 Develop a particular process of filtering data adapted to this case.

1. Backscattering applied to the detection of paleochannels in seismic nanozonation analysis in Barcelona city
Low activity seismic zone - rural
geology
2. Study of the shallow geology of Torre d’ Oristà
2. Study of the shallow geology of Torre d’ Orist
à
2.1 Determine the depth of the sediments
2.2 Locate the rock formation
2.3 Develop of a methodology adequate to the usage of low frequency non blinded antennas.
2.4 Compare the obtained results with numerical simulation.

Low activity seismic zone - urban
structures
3.1 Application of the 3D process to cylindrical geometry.
3.2 Development of a methodology to survey curved surface.
3.3 Obtain 3D images to represent the intern structures and possible pathologies.
3.4 Compare the results achieved with GPR with other NDT and techniques.

3. Evaluation of the masonry columns from Hospital de Sant Pau i la Santa Creu.
4. Assessment of the Museum of Contemporary art of Valdivia (MAC).


High activity seismic zone - urban
structures
4.1 Development of a methodology of acquisition to prospect the museum.
4.2 Characterization of the structural arrangement of ground floor and the walls at distinct levels.
4.3 Detection of pathologies caused by high water content, sunken layers and high salinity.
4.4 2D and 3D images of the structures and the pathologies.

5. Evaluation of the buildings terraces -
Eixample
of Barcelona.


5.1 Development of the methodology
to prospect the terraces.
5.2 Type of material using the amplitude of reflection.
5.3 Disposal of the 3D elements structures.
5.4 Associate structural typologies with characteristic radar images.

Low activity seismic zone - urban
structures
6.1 Creation of a program to define backscattering noise by the analysis of the amplitude for each A- Scan along each B-Scan.
6.2 Determine the central frequency variation to relate with the water content.
6.3 The study of wavelets to evaluate and characterize the backscattering noise.

Algorithms
References
Geology and mining
Thematic
Patent: by Levi and Leimbach (1910-1911)
Kozlovsky et al (1989) and Finkelshtein et al (1986)
El said (1956)
Water table
Second world war
Waite and Schmidt (1961)
Geological surveys - Aircraft
Glaciology - polar environments
Walford (1964)
1910
1940
1956
1961
1964
Morris (1962)
GPR - General

State of the Art
References
Salt deposits and coal mines
Thematic
Holser et al. (1972) and Cook (1973)
Ulriksen (1982)
Roads
Nuclear waste disposal
1972
Olsson et al. (1987)
1982
1987
Archaeology
Goodman (1994)
Environment
Redman et al. (1996)
1994
1996
State of the Art
Paradigmatic references and reviews

Author
Ground-Penetrating Radar: an introduction for archaeologists.
Thematic
Annan (2002)
Goodman (1994)
Conyers and Goodman (1997)
GPR—History, trends, and future developments. Subsurface Sensing Technologies and Applications.
Ground-penetrating radar simulation in engineering and archaeology.
Ground penetrating radar: theory and applications.
Jol (2009)
State of the Art - General
State of the Art - Specific
Applications
Range
Type
PART I - Theory
Maxwell equation
Delta Dirac
Soil properties
dielectric constant
electrical conductivity
magnetic permittivity
Velocity
Coefficient of reflection (R)
Velocity
PART II - Laboratory experiments and data processing
PART III - Geological applications
PART IV - Heritage and Civil structures applications
PART V
12. Discussions and conclusions

7. Laboratory experiments
Grain size particle
Evaluation of the velocity in the medium
Backscattering
Numerical simulation
6. Data processing
Introduction - Noise
Radar data processing :
time
and
frequency
domains
Wavelets
7. Backscattering applied to the detection of paleochannels in seismic nanozonation analysis in Barcelona city
8. La Torre D’ Orista
9. Study of supporting structures in the Hospital de la Santa Creu i Sant Pau
10. Contemporary building - Museum of Contemporary Art of Valdivia (MAC), Chile
11. Roofs of the buildings - Eixample (XIX century) – Barcelona
Resistivity
Before
After
Drying process
Results
Methodology
Methodology - Gravel
Gravel - Particle size analysis
Results
Raw data
Processed data
During the water intrusion

After the water intrusion
Medium in equilibrium

- background removal
- energy decay (gain)
Phases
Processes
Adding water
Waiting for the equilibrium
30 min
Processing data
4L
Gravel Type A
Gravel Type B
Methodology
Time domain filters
Frequency domain filters
DC
Gain
•Automatic Gain Control – Gain (ACG)

Energy decay
• Gain function
• Remove header gain
• Div. compensation

Manual gain (y)
• Manual gain (x)
• Scaled windowgain (x)
• X-distance decay (db)
• Compensate stripes

Dewow
Original
Processed
Original
Processed
Time
Frequency
Fourier transform
Band Pass filter
Notch filter
Amplitude noise - Subtract mean trace
Original signals
Level of decomposition - Haar 5
Frequency
Diagonal Avenue
Mean amplitude
Mallorca Street
Mean amplitude

Method 1
Method 2
Framework
Soundings
Framework
Radar data acquisition
Radar data acquisition
Results
Numerical simulation
3D Model
Final results
Comparison with
H/V
Passive Seismic
Parameter
Centre frequency 1.6 GHz
Sampling Frequency 86273.84 MHz
Samples 672 samples per trace
Time window 7.9 ns
Spatial Sampling: 0.2 cm

Case 1 - Sant Marcus Column
The target
Results
Historical pictures
Geology
The target
Case 2 - Column 1
Results
The target
Case 2 - Column 2
Results
Walls
The target
Results
Results
Results
The target
Results
Column in perfect state
Endoscopy

500 MHz antenna
Cristian Undurraga
Outside
800 MHz antenna
Inside
Data acquisition
Cristian Undurraga
Inside
Results
Data acquisition
Results
Slices - C Scan - depth
B Scan - x cuts
Full 3D
B Scan - x cuts
3D model
The plan - Zones to assess
Location
Geology
Location
Seismic
Risk

Consequences of the 1980 Seism in:
Chile
Japan
Present
Past
Future
Pathologies
Equiment
- walls
- resolution
- penetration
at least 1 m depth
- floor
- resolution
- penetration
at least 2 m depth
Evaluation of the propagation velocity
Results
Data acquisition
Light conditions
Typical terrace - Data acquisition
Pattern to define:
- Material type
- Structural arrangement
Material type
Structural arrangement
Case A
Case B
Data acquisition
Data acquisition - Profiles
Final model
Data acquisition
Data acquisition - Profiles
Final model
Low activity seismic zone - urban
geology
1. Study of the shallow geology of Barcelona
1.1 Locate the paleochannels.
1.2 Locate underground streams.
1.3 Compare GPR with H/V and maps.
1.4 Develop a particular process of filtering data adapted to this case.

1. Backscattering applied to the detection of paleochannels in seismic nanozonation analysis in Barcelona city
Low activity seismic zone - Rural
Geology
2. Study of the shallow geology of Torre D’ Orista
2. Study of the shallow geology of Torre D’ Orista
2.1 Determine the depth of the sediments
2.2 Locate the rock formation
2.3 Develop of a methodology adequate to the usage of low frequency non blinded antennas.
2.4 Compare the obtained results with numerical simulation.

Low activity seismic zone - urban
structures
3.1 Application of the 3D process to cylindrical geometry.
3.2 Development of a methodology to survey curved surface.
3.3 Obtain 3D images to represent the intern structures and possible pathologies.
3.4 Compare the results achieved with GPR with other NDT techniques.

3. Evaluation of the masonry columns in the Hospital de la Santa Creu i Sant Pau.
4. Assessment of the Museum of Contemporaneous Art of Valdivia.


High activity seismic zone - Urban
Structures
4.1 Development of a methodology of acquisition to prospect the museum.
4.2 Characterization of the structural arrangement of ground floor and the walls at distinct levels.
4.3 Detection of pathologies caused by high water content, sunken layers and high salinity.
4.4 2D and 3D images of the structures and the pathologies.

5. Evaluation of the buildings terraces -
Eixample
of Barcelona.


5.1 Development of the methodology
to prospect the terraces.
5.2 Type of material using the amplitude of reflection.
5.3 Disposal of the 3D elements structures.
5.4 Associate structural typologies with characteristic radar images.

Low activity seismic zone - Urban
Structures
What is
RADAR
?
RA
dio
D
etection and
R
anging
Detects and measures
1956
1961
1964
How does it work?
Emission
and
reception
of high frequency (10 MHz to 8 GHz) electromagnetic waves
1956
1961
1964
1956
1961
1964
How should we
regulate
the assessment with
GPR
?
1956
1961
1964
A-Scan
I
II
Conic shape
Surface
Medium
Illuminated area
Time window
PARAMETERS
Sampling frequency
Antenna separation
Sampling interval
Data quality
- Velocity of acquisition
- Files size
B-Scan
C-Scan
1960
last 20 years
Geology
McKee et al. (1964):
sand sunes
Jol et al. (2003):
sediments
Beres and Haeni (1991):
coast environments
Moslow and Heron (1978):
paleochannels
Cultural Heritage
McGill (1995):
walls
Binda et al. (1998):
masonry ; water content
Garcia et al. (2007):
crypt

Pérez-Gracia et al. (2008):
Roman theatre
Water content
Topp et al. (1984):
dielectric constant
Schmalz et al. (2002):
wave amplitude
Stleeman and Endres (2011):
petrophysics
Benedetto (2010):
frequency peaks
Seismic studies
Aggelopoulos et al. (1996):
burried persons
Cardimona et al. (1998):
seismic, reflection
Journal of Applied Geophysics
Remote sensing
NDT & E International
Engineering Failure Analysis
Journal of Earthquake Engineering
International Journal of Rock Mechanics and Mining Sciences
Journal of Archaeological Science
Sedimentary Geology
Digital Signal Processing
Engineering Geology
Construction and Building Materials
Near Surface Geophysics
Archaeological prospection
JOURNALS
International Conference in Ground Penetrating Radar (ICGPR)
International Workshop in Advances in Ground Penetrating Radar (IWAGPR)
European Geosciences Union (EGU)
European Association of Geoscientists of Engineers (EAGE)
Near Surface Geoscience conference (NSG)
World Conference on Earthquake Engineering (WCEE)
International Conference on Engineering Failure Analysis (ICEFA)


Conferences
EuroGPR



COST ACTION TU1208 - Civil Engineering Applications of Ground Penetrating Radar

Association
GPR data processing
Wavelets
Kovalenko et al. (2005):
mining; pre-filtering
Geraads et al. (2002):
notch filter; railways
Hereman (2000):
theory and applications
Hinterleitner et al.:
(2009) low pass filtering ; high resolution
Baili et al. (2009):
denoising; filtering
Haar (1900):
theory
GPR - General

State of the Art
The GPR has been applied as seismic support studies.
The methodology to determine geological elements and to recognize and distinguish the internal structural elements in buildings (for nanozonation and microzonation).
Laboratory tests, radar data processing improvements, numerical simulation could corroborate the interpretation of the field data and to understand the GPR response in the assessed media.

Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 11
Future lines
The objectives analyzed in this thesis, and the results obtained after the works, highlights possible future work lines in this field. A short resume of the main points that could be continued are listed below:


Develop a relationship to determine, qualitatively, the variation of the central frequency with the water content and develop the respective simulation.
• Determine a function between the scattering phenomenon with several particle sizes, already simulated for few particle sizes.
• Detect automatically, scattering by imaging treatment.
• Applying the backscattering noise in structures in order to associate to damage.




Endoscopy
Results
Seismic tomography
Laboratory assessment
Laboratory assessment
The target
Results - Processed data
Results - Interpreted data
Isoamplitudes
Circular radargrams in a 3D view
The target
Radar data acquisition - vertical and horizontal profiles
Results - Processed data
Results - Interpreted data
Results
Interpreted data
Circular radargrams in a 3D view
Circular radargrams in a 3D view - interpolation
3D interpolation of the inner anomaly
Comparison between the real target and the 3D model obtained with the GPR
1. GPR was able to locate paleochannels by two different methods:
- Method 1 by the regular use of GPR
- Method 2 by the mean and maximum value of backscattering
2. The difference between the GPR results and the historical may be due the natural or anthropogenic changes courses or the inaccuracy of historical maps
3. The identification of the paleochannels support seismic risk studies once these geological structures represent soil lateral changes and to density the HV measurements
4. This methodology can be further applied to structures with damage that produce backscattering.
5. The time window can be changed according to the depth of prospection.
Main conclusions
1. The low frequency antennas could detect the depth of the sediments and the rock formation.
2. The numerical simulation could reproduce the effect obtained in field of intersection of two geological layers .
3. The final results provide information of the maximum depth to dig for archaeological assessments.

1. The GPR was able to define the structural arrangement of masonry columns and the respective pathologies.
2. It was possible to detect structures of support in the Sant Marcus columns and an inner anomaly in the columns of the Pharmacy Pavillion.
3. Even if the surface suggested that the column was wrapped with equal bricks, GPR results shows that for some columns the bricks are irregular.
4. The 3D representation in cylindrical coordinates allows to identify the targets with the real shape and allowed to compare with the real target.
5. The cited representation can be extended to any structure feasible to be assessed with the GPR with non uniform shape.
6. Seismic tomography and endoscopy corrobated GPR results
Assessment of the Museum of Contemporary Art of Valdivia.


1. The application of two different antennas (500 MHz and 800 MHz c.f. antennas allows assessing the MAC in a high seismic risk zone. Development of a methodology of acquisition to prospect the museum.
2. The prospection in the walls could define its thickness and the floor was feasible to define the structural arraignment and the of the constructivist materials.
3. The main pathologies of the building were found in the floors: sunken layers, high signal attenuation and high water content.
4. The developed 3D model could provide real scale images derived from the GPR results.

1. The GPR assessment in the Terrace permitted to identified the structural arrangement of the constructive elements and the material type.
2. The 2D models provide the necessary information to determine the weight of the terrace and to the seismic response studies.

Evaluation of the buildings terraces -
Eixample
of Barcelona.



1. GPR experiments lead to define wave propagation velocity (13 cm/ns) for a dry medium using both a metallic bar to create a hyperbole and using the TWT, measuring the exact depth or finally, by migrating the hyperbole.
2. The determined velocity of the medium is higher (13 cm/ns)
3. The dielectric constant was closed to the a CRIM model for the first values of humidity and to the Topp model for higher values of humidity.
4. The velocity decreased for higher values of water content according the theoretical values for saturated medium (3 cm/ns)
5. The scattering could be reproduced under controlled conditions both in laboratory experiments and numerical simulation.
Daniels (1996)
Surface-penetrating radar
Scattering
S
ignal-to-
N
oise
R
atio
High
SNR
Low
SNR
Method 1- Regular use
of GPR
Method 2- Use of noise
scattering amplitude
Frequency spectrum vs water content
sample 1 - 2.3%
sample 2 - 3.6%
sample 3 - 6.5%
sample 5 - 10.6%
sample 4 - 7.2%
sample 6 - 12.6%
sample 1 - 2.3%
sample 6 - 12.6%
sample 1 - 2.3%
sample 6 - 12.6%
sample 1 - 2.3%
sample 6 - 12.6%
sample 1 - 2.3%
sample 6 - 12.6%
sample 1 - 2.3%
sample 6 - 12.6%
sample 1 - 2.3%
sample 6 - 12.6%
sample 1 - 2.3%
sample 6 - 12.6%
sample 1 - 2.3%
sample 6 - 12.6%
Objective:
-detect with accuracy the location of paleochannels
-densify the HV measurements

Initial data:
- punctual soundings
- historical maps (Ventanyol et. al, 2000)
Method 2
Comparison
with method 1
Why is there difference of location between GPR and the map?


Chapter 7
Main conclusions
La Torre D' Orista


Main conclusions
Main conclusions
Chapter 10
Study of supporting structures in the Hospital de Santa Creu i Sant Pau


Main conclusions
Backscattering applied to the detection of paleochannels in seismic nanozonation analysis in Barcelona city
Laboratory experiments
Main conclusions
Acknowledgements
Dr Vega Pérez-Gracia
Dr Ramón González-Drigo
Dr Lluis Pujades
Dr Daniel di Capua
Dr Oriol Caselles
Dr Jaume Clapes
Victor Salinas
Joan Sahun
Josep Pedret
Pau Gimeno
Ferran Ballester
Marcos Sanz
Dr Galo Valdebenito
Dr Victoria Vasquez
Engineer Victor Aguilar
Engineer David Alvarado
Engineer Juan Pablo Muñoz
Enginner Pilar Aburto
Dr Josep López López
Antonio Sánchez Egea
Amélia Nápoles
Dr Antonio Traviesso
Mari-Carmen Rodriguez

1. The radar data processing carried out in Matlab could control the input parameters of filtering
2. Different types of filtering have successfully applied both in time and frequency domain
the first values of humidity and to the Topp model for higher values of humidity
4. The new algorithm allows analyzing the mean and maximum backscattering for urban geological applications.
5. The wavelets proved that for different frequencies the amplitude increases for higher water content.
6. The 3D processing in cylindrical coordinates allows representing the anomalies in the real shape.
Laboratory experiments
Main conclusions
Principal contribuitions
Interfaces
Coefficient of reflection
water - air
water - clay
water - sand
0.8
0.05-0.1
0.3-0.4
water - limestone
0.5
clay-clay/silte
0.1
0.1
clay-sand
sand-limestone
clay-limestone
sand-granite
0.2
0.3
0.4
GROUND PENETRATING RADAR APPLICATIONS IN SEISMIC ZONATION: ASSESSMENT AND EVALUATION
Index
Objectives
Introduction
PART I- Theory
Main field chapters and state of the art
PART II - Laboratory experiments and data processing
PART III - GPR applied to (urban and rural) shallow geology
PART IV - GPR applied to (high and low seismic risk zones) civil structures in cultural heritage
PART V - Discussions and conclusions
Contributions
Publications
Acknowledgments





1. Development and applicability of the analysis of
background noise
of the traces caused by backscattering
to detect irregular materials
.
2. Applicability in
seismic zonation
.
3.
3D images of non-flat structures
to define better the
inner targets
.

Publications
1.
Assessment of Complex Masonry Structures with GPR
Compared to Other Non-Destructive Testing Studies
in
Remote Sensing
Sonia Santos-Assunçao, Vega Perez-Gracia, Oriol Caselles, Jaume Clapes,
and Victor Salinas.
2.
Nanozonation in Dense Cities: Testing a Combined Methodology in Barcelona City (Spain)
in
Journal of Earthquake Engineering
V. Salinas, J., O. Caselles, V. Pérez-Gracia, S. Santos-Assunçao, J. Clapes, L. G. Pujades, R. González-Drigo b, J. A. Canas and J. Martinez-Sanchez.


To be published
1.
Non-destructive testing of the Ancient Tholos Acharnon Tomb to assess the structure and define geometry
in
Near Surface Geophysics
. Sónia Santos-Assunçao, Klisthenis Dimitriadis, Yiannis Konstantakis, Vega Pérez-Gracia and Eirini Anagnostopoulou.
2.
GPR backscattering applied to detect paleochannels and infilled streams for seismic nanozonation in Barcelona city
in
Journal of Selected Topics in Applied Earth Observations and Remote Sensing
.
S. Santos-Assunçao, V. Salinas, V. Pérez-Gracia, O. Caselles and R. González-Drigo.

Award
: Best paper oral presentation in the
15th International Conference on Ground Penetrating Radar
GPR 2014 - Brussels
Published on: 12 º Spanish national congress of
non-destructive techniques
Cost Action TU 1208
- Civil Engineering Applications of Ground Penetrating Radar

My family
Maria Santos
Fábio Assunção
Cláudia Assunção
Ilidio Assunção
Bruno Scotto
Angelina Sousa
Sebastião Santos
Teresa Silva
Victoria Fernández
Fiorella Scotto


My friends
Damian Rocha
Laia Plantada Xarrie
Nuno Niguel Magalhães
Christina Sotiropoulou Doris Hebenstreit
Marta Kulbacka
Laetitia Dupaix
Ester Franco



Thank you very much for your attention
Full transcript