Download Monitoring ground displacement with satellite radar systems

Continuous, Remote and Long-Term
Tunneling Monitoring with InSAR
INFORMATION FROM SPACE
Authors: C. Giannico, A. Belson, A. Urdiroz, G. Falorni
Presenter: Alessandro Ferretti
tre-altamira.com | © TRE ALTAMIRA 2016
Overview
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Introduction
»
InSAR: The Technology
»
Present and future trends
»
Applications to civil engineering and tunneling monitoring
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Summary
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About TRE ALTAMIRA
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Leading providers of InSAR solutions for measuring ground motion:
Offices in Barcelona, Vancouver and Milano
Largest InSAR group (>75 people)
Worldwide presence and operations
Part of the CLS group
Processing Centre specifically designed for InSAR data processing
Continuous R&D and innovation activities
Proprietary techniques and tools: SqueeSAR™, DespecKS™, TREmaps™
Milano team
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Barcelona team
Vancouver team
Data center, Milano
ALTAMIRA and TRE joined forces and became the largest InSAR group worldwide
INSAR: THE TECHNOLOGY
The secret behind interferometry:
the wavelength is the “unit of length”
 (cm)
ΔR
R2
R1
time
R1
ΔR
Reflecting object
R2
Advanced InSAR Analysis
Ground Measurement Points
time
Multi-temporal satellite
acquisitions
Time-series of deformation
SqueeSAR™: Information Provided
A SqueeSAR™ analysis provides the
following main info:
• Measurement Point (PS/DS)
Position [m] (lat, long, height)
• Measurement Point (PS/DS)
Annual Displacement Rate [mm/yr]
[mm]
Time series of displacement
[time]
• Measurement Point (PS/DS)
Displacement Time-Series [mm]
An example over a city: London
Accuracy
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Positioning
EASTING
NORTHING
HEIGHT
C-band data
±7m
±2m
± 1,5 m
X-band data
±3m
±1m
± 1,5 m
Precision (1)
»
Displacement
Precision (1)
LOS displacement
Average
displacement rate
Single
measurement
< 1 mm/year
± 3 mm
Nominal values for datasets of >40 images and for MP <4 km from REF
Main market sectors
1. Oil&gas:
• Environmental monitoring
• Reservoir optimization
• pipeline monitoring
2. Public administrations:
• Landslide mapping
• Natural hazards
3. Engineering companies:
• Infrastructure monitoring
• Route planning
4. Mining companies:
• Open pit monitoring
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NEW TRENDS
Wide Area Mapping
ESA SAR data
>8,000 SAR scenes
>20,000,000 PS
Visualization technology
Web-platform for fast
• Visualisation
• Delivery
• Storage
of SqueeSAR™ results
New High Resolution Data
TerraSAR-X
Double-Geometry Analysis
Ascending
Descending
θ θ
ddesc
PS
dreal
dasc
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APPLICATIONS FOR CIVIL ENGINEERING
InSAR Applications Civil Engineering
Planning
Construction
− Prior to construction: ground motion
analysis ante operam (based on satellite
archive data) can help identify unstable
areas and allows users to add another layer
of information during the design phase
− During construction: InSAR data can
assess the impact of big construction works
on the surrounding area, especially in
densely populated urban areas
− Post-construction phase:
- Post operam monitoring of surface
deformation phenomena and – in
general – of possible displacements
- A posteriori analyses possible thanks to
satellite archives from 1992
Maintenance
- quantification of possible displacements
affecting the infrastructure and the
surrounding areas.
Radar technology measures motion before, during and after construction in order to make decisions 17
about viability and safety at every stage.
Monitoring Excavation Works
Railway tunnel construction
Sicily, Italy
Railway tunnel in urban area
Sicily, Italy
InSAR was used:
• To gain insight about the
displacement field affecting the AOI
ante operam.
• To get information about the spatial
extent and the magnitude of surface
settlement (in synergy with in situ
instrumentation)
Two High Resolution (HR) X-band
datasets were processed to estimate both
vertical and east-west horizontal
displacements.
Barla et al., 20016 – InSAR Monitoring of tunnel induced ground movements. Geomechanics and Tunnelling (9, 2016)
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Time-lapse analysis
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»
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Time-lapse analysis of the displacement time series.
Correlation between deformation and tunnel face advancement.
Extent of the subsiding area and amount of lost volume calculated for each
period.
01/2012 – 06/2012
06/2012 – 12/2012
Vertical Displacement
12/2012 – 06/2013
Key findings
01/2012 – 06/2014
»
The area affected by significant
deformation turned out to be
larger than expected.
»
InSAR data provided a
characterization of the surface
deformation occurring before,
during and after tunnel excavation.
The integration of InSAR
information with in situ data
(boreholes, cross-hole) turned out
to be extremely helpful to
understand the reasons of an
abrupt compaction phenomenon
that affected some buildings (which
were evacuated).
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Metro lines network construction
Paris, France
InSAR for the Grand Paris Express
Yesterday, Today and the Next 10 years
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InSAR Grand Paris Express Project
2015
2014
2013
2012
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
High resolution historical study by section (2011-2015)
The analysis of this section provides a good example of the high density of measurement points achievable
wit High-Resolution X-band SAR data. InSAR monitoring activities are planned until 2025. 25
Canada Line construction
Vancouver, Canada
Canada Line
Opened in August 2009
SINGLE BUILDING ANALYSIS
Millennium Tower – San Francisco
Completed in 2009, the 58-storey
Millennium Tower has recently been
showing signs of sinking and tilting.
Although the cause has not been
pinpointed, it is believed that the
movements are connected to the
supporting piles not firmly resting on
bedrock.
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Medium-Resolution – Sentinel-1 InSAR data
http://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Sentinel-1/Satellites_confirm_sinking_of_San_Francisco_tower
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High-Resolution – TerraSAR-X InSAR data
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SUMMARY
Conclusions
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Thanks to its high precision and to the availability of satellite data archives covering
two decades, SqueeSAR™ represents one of the most powerful technique able of
detecting surface displacements.
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The processing of archive satellite data allowed additional assessment of
deformational behaviour ante operam (i.e. before the start of tunnelling activities),
and therefore independent of any construction work
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InSAR data cannot be used as a real-time monitoring tool due to the current revisiting
times of the satellites (a few days), but the number of “continuous monitoring”
projects is increasing steadily.
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The capability of SqueeSAR™ to remotely monitor areas much wider than any
traditional surveying technique (without the necessity to install anything on ground),
makes InSAR data particularly suitable for complementing in situ instrumentation and
define the best locations for in situ instruments.
TRE
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