sao paulo collapse
TRANSCRIPT
Lessons Learnt from Accidents in Urban Tunnels
Prof. André P. Assis, PhD(UnB / ITA)
EPFL Master on Advanced TunnellingLausanne, Switzerland – May 2011
Introduction
General Trends in the Tunnelling Industry
High risk type construction methodsTrend towards design + build contractsOne-sided contract conditionsTight construction schedulesLow financial budgetsFierce competition in construction industries
Decade 1990
Major Tunnel Losses since 1994
1994 Heathrow Express Link, GB Collapse US$ 141 mio
1994 Metro Taipei, Taiwan Collapse US$ 12 mio
1994 Munich Metro, Germany Collapse US$ 4 mi
1995 Metro Los Angeles, USA Collapse US$ 9 mio1995 Metro Taipei, Taiwan Collapse US$ 29 mio
PROJECT CAUSE LOSS
1999 Hull Yorkshire Tunnel, UK Collapse US$ 55 mio
1999 TAV Bologna - Florence, Italy Collapse US$ 9 mio2000 Metro Taegu, Korea Collapse US$ 24 mio
Major Tunnel Losses since 1994
PROJECT CAUSE LOSS2000 TAV Bologna - Florence, Italy Collapse US$ 12 mio
2002 Taiwan High Speed Railway Collapse US$ 30 mio
2003 Shanghai Metro, PRC Collapse US$ 80 mio2004 Singapore Metro, S’pore Collapse t.b.a.
2005 Barcelona Metro, Spain Collapse t.b.a.2005 Lausanne Metro, Switzerland Collapse t.b.a.2005 Lane Cove Tunnel, Sydney Collapse t.b.a.
2005 Kaohsiung Metro, Taiwan Collapse t.b.a.
2007 Sao Paulo Metro, Brazil Collapse t.b.a.and so on …
Statistics on Causes of Accidents
Accidents DuringConstruction: Last
Decade Scenario
Significant increase in the number of claimsInsurance income <<< Claims outcomeInsurance paid >>> Initial cost of the work Difficulties to insure underground works
Options of the Insurance Market
Stop insure underground works
Increase insurance prices and tight conditions
Professional approach to the problem involving all related parts
Focus on other markets
Insurance may become not feasible
Proposal of a code of practice for risk management
Aims and Results of the Code of Practice for Risk Management
Establish minimum standards for evaluation of risks and procedures of risk management
Clear definition of responsibilities of all involved parts
Reduce probability of lossesReduce number and size of claimsRe-establish the trust of insurance companiesTransfer the concept of good practice to other market sectors
18.05.2011
“No construction project is risk free.
Risk can be managed, minimised,
shared, transferred or accepted.
It cannot be ignored.”
Sir Michael Latham, 1994
IntroductionIPT Investigation Work and ReportMain IPT Report FindingsConclusions and Recommendations
Lessons Learnt from the PinheirosStation Accident in Sao Paulo, Brazil
Barton, N. (March, 2008)
IPT (June, 2008)
CVA (August, 2008)
Existing Technical Reports on the PinheirosStation Accident
Introduction: SP Metro Line 4
Introduction: SP Metro Line 4
PinheirosStation
Introduction: Pinheiros Station
Pinheiros StationDesign (primary
support)
Pinheiros StationDesign (final support)
Pinheiros StationConstruction
Scheme
Introduction:Pinheiros Station
Accident
Occurred on 12/01/2007During the bench excavation, very close of arriving to the shaftFirst failure signs ~14h30Daylight collapse at 14h54Enormous material damages and 7 fatalities
IPT commissioned the technical investigation
IPT Investigation Work and Report
IPT Commission (team of in-house specialists)Board of Consultants (4 Brazilians and 2 foreigners)Independent Auditing Firm (RinaInternational)
Desk StudiesFollowing-up of the collapse debris excavationInterviews with involved staff from all parties
Chapters 1-3: Introduction, objectives & scopeChapter 4: Urban tunnellingChapter 5: Trends in contractual practicesChapter 6: Pre-bidding knowledgeChapter 7: Contractual aspects of Line 4Chapter 8: Design and constructionChapter 9: CollapseChapter 10: Mechanism and causesChapter 11: Conclusions and Lessons
IPT Report (main report 384 p.+ 46 appendices ~3000 p. + video)
10 years of studies till biddingAmount of geological and geotechnical investigation and level of engineering design had been continuously upgraded very reasonable and adequateGeological-geomechanical model
Hasui (1993)IPT (1997)Figueiredo Ferraz (2001)
IPT Main Report:Pre-Bidding
Caucaia Shear Zone
PinheirosStation
N
Geological-Geomechanical Model
Pre-Bidding
From impressiom packer in Pinheiros station area and reginal surveys (319 poles) From scanlines on the
final surface (26 and 522 poles)
Structural Geology – 4 families
Geologicalinterpretation
considering strutcturalinformation
142610 142630 142650 142670 142690 142710 142730 142750 142770 142790
178120
178140
178160
178180
178200
SR-01
SR-02
SR-03
SR-04
SR-05
SR-06
SR-07SR-08
DE-SM-ML4-23
SM-8700
SM-8701
SM-8702
SM-8703
SM-8704
SM-8705
SM-8706
SM-8707
SM-8708
SM-8714
SM-8719
SM-8720SP-8709
SP-8710
SP-8711SR-8584
DAS
NAÇ
ÕS
UN
IDA
S
SM-6802
SM-6530
SM-6532
SM-6803
Filonite (SR-07)
142645 142665 142685 142705 142725 142745 142765 142785178125
178145
178165
178185
178205
178225
178245
178125
178145
178165
178185
178205
178225
178245
142645 142665 142685 142705 142725 142745 142765 142785
Pinheiros Station: Geomechanical sections obtained from 3D interpolation using structural
geology information
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150680
690
700
710
720
680
690
700
710
720
WSW ENE
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140680
690
700
710
720
680
690
700
710
720
WSW ENE
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140680
690
700
710
720
680
690
700
710
720
WSW ENE
Longitudinal sections (central, north side and south side)
Blue - fill
Yellow – alluvium
Green – tertiary sediments
Brown – weathered soil
Dark gray – RMR IV
Medium gray – RMR III
Light gray – RMR II
(rock mass classification from designer)
680
690
700
710
720
680
690
700
710
720
0 10 20 30 40 50 60 70 80 90 100 110 120
NNW SSEeixo entrevias
680
690
700
710
720
680
690
700
710
720
0 10 20 30 40 50 60 70 80 90 100 110 120
NNW SSEeixo entrevias
680
690
700
710
720
680
690
700
710
720
0 10 20 30 40 50 60 70 80 90 100 110 120
NNW SSEeixo entrevias
680
690
700
710
720
680
690
700
710
720
0 10 20 30 40 50 60 70 80 90 100 110 120
NNW SSEeixo entrevias
Cross-sections obtained from 3D interpolation
Sub-vertical alternation of granitic and biotitic gneiss, with variable thickness (sub-parallel to the tunnel longitudinal section)Four families of discontinuitiesRockmass is heterogeneous and anisotropic due to discontinuities and uneven weathering bedrock surface as egg box type
Post-bidding investigation confirmed the GG model developed during the pre-bidding design
Geological-Geomechanical
Model
Geomechanical model adopted did not consider the anisotropy due to discontinuities
Assumptions and calculations2D analysis shaft effect neglectedOversimplified constitutive law for the soils above tunnelGround assumed fully drained
Design analyses indicated critical stability conditions during the bench excavation phase
IPT Main Report:Design Shortcomings
Monitoring and InstrumentationInstruments
4 sections (5 convergence pins)4 sections (3 extensometers)Some open-pipe piezometers
Threshold values for the instrumentationShaft: all threshold values definedTunnel: only the expected value calculated, but no definition of the warning and emergency values (qualitative criteria)
No evidence of backanalyses
IPT Main Report:Design Shortcomings
Quality control based on self-certificationPoor control of methods and materials
Forepoling fillingQuantity of sprayed concrete fibresEarly-age strength of sprayed concrete
Deficient quality managementInternal auditing systemGeomechanical mappingInstrumentation data interpretation
IPT Main Report:Construction Aspects
Risk Management (contingency and emergency actions)
Three main design violations during construction
Inversion of the excavation direction of the bench towards the shaftIncrease of the bench height (4 to ~5 m)Change of the bench excavation sequence (also the rate: 1.8 m/d in January 2007 and 0.9 m/day in December 2006)
IPT Main Report:Construction Aspects
-25
-20
-15
-10
-5
0
5
23/1
1/06
03/1
2/06
13/1
2/06
23/1
2/06
02/0
1/07
12/0
1/07
Data
Rec
alqu
e (m
m) 7.0+86 - P1
7.0+86 - P2
7.0+86 - P3
7.0+96 - P1
7.0+96 - P2
7.0+96 - P3
7.1+06 - P1
7.1+06 - P2
7.1+06 - P3
7.1+15 - P1
7.1+15 - P2
7.1+15 - P3
-40,0
-35,0
-30,0
-25,0
-20,0
-15,0
-10,0
-5,0
0,0
5,0
15/0
8/06
25/0
8/06
04/0
9/06
14/0
9/06
24/0
9/06
04/1
0/06
14/1
0/06
24/1
0/06
03/1
1/06
13/1
1/06
23/1
1/06
03/1
2/06
13/1
2/06
23/1
2/06
02/0
1/07
12/0
1/07
22/0
1/07
Data
Con
verg
ênci
a (m
m)
7.0+867.0+967.1+67.1+15
Few Days before
Collapse
Meeting on 11/01/2007
Installation of bolts in the tunnel bench walls decided No enough bolts in stock, despite it was forecasted
in the design as contingency action (15% installed but all borehole drilled)
Three blasting on the 12/01/2007 (two around 8 h, one in each platform tunnel, and a third one around 12 h)
No clear definition on the need to stop the works (contradictory version among participants)
The Colapse
Fall of small concrete blocks
Fracture propagation from the shaft till 1/3 of the tunnel length, position 11 h
Fall of 6 to 8 lattice girders in the left-hand side wall Colapse daylight on surface at
14h54 Colapse of the north wall of the
shaft at 15h30 (last event)
Main Report Findings:Collapse Evidences
eixo
-14
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
23/1
1/06
03/1
2/06
13/1
2/06
23/1
2/06
02/0
1/07
12/0
1/07
22/0
1/07
Data
Rec
alqu
e (m
m)
TN.E-1TN.E-2TN.E-3TN.F-1TN.F-2TN.F-3TN.G-1TN.G-2TN.G-3MS1TN.H1TN.H-3
Instrument Position Calculated(mm)
Observed on 11/01/07 (mm)
Observed / Calculated
ExtensometerAxis -0,7 -11 17
Lateral Wall -0,7 -12 19
Convergence Pins
(Settlement)
Axis -0,7 -7 10
Upper -0,9 -20 22
Lower -0,5 -7 13Convergence P2-P3 -0,2 -21 95
13/1
2
23/1
2
02/0
1/20
07
Collapse:Instrumentation
Data
Instrumentation evidences
Main Report Findings:Collapse Evidences
0
5
10
15
20
25
30
0
5
10
15
20
25
30
ESTACAS 7,0+86 / 7,0+97 / 7,1+06 / 7,1+150
5
10
15
20
25
30
0
5
10
15
20
25
30
ESTACAS 7,0+86 / 7,0+97 / 7,1+06 / 7,1+15
NOV29
DEZ15
DEZ27
JAN02
JAN08
JAN09
JAN10
JAN11
JAN12
JAN12T
PINO 2 PINO 3
VISTA GERAL DOS ESCOMBROS
Debris position evidences
Main Report Findings:Collapse Evidences
Section 7,0+87
Section 7,1+04
Section 7,1+13
Main Findings: Collapse Mechanism
142735 142745 142755 142765 142775 142785
142735 142745 142755 142765 142775 142785
178165
178175
178185
178195
178205
178165
178175
178185
178195
178205
?
P-2
P-2
P-2
P-2
P-3
P-3
P-3
P-3
TN.E1
TN.E2
TN.E3
TN.F1
TN.F2
TN.F3
TN.G1
TN.G2
TN.G3
TN.H1
TN.H3
TN.E1
TN.E2
TN.E3
TN.F1
TN.F2
TN.F3
TN.G1
TN.G2
TN.G3
TN.H1
TN.H3
Medidas de recalque nos tassômetros referenciadas a 11/01/07
Non-Validated DesignOversimplified geomechanical modelStructural tunnel modelAssumptions and completeness of calculations and simulationsNo definition of threshold values for monitoringDeficient GG mappingDeficient analysis and interpretation of monitoring dataNo evidence of back-analyses and design validation
Main Report Findings:Risk Factors and Causes
Non-Validated Construction ProcedureChange of excavation directionIncrease of bench heightChange of blasting schemeDeficient quality controlIncrease of excavation rateDeficient construction management (lack of bolts)No decision to stop worksDeficient plans of contingency and emergency actions
Main Report Findings:Risk Factors and Causes
Main Report Findings:Risk Factors and Causes
Non-validated design
Non-validated construction procedure and poor management
Collapse of Pinheiros Station
Accident Collapse and its Consequences
Presence of transit and pedestrians
Fault of the emergency plan of actions
Risk Factors and Causes:Foreseeability and Other Aspects
Different ground conditionsExcessive rainSeismic activityPipe leakage
ForeseeabilityClear under good practice of engineering Misty by faults in several engineering processes
-16,0
-14,0
-12,0
-10,0
-8,0
-6,0
-4,0
-2,0
0,0
2,0
4,0
29/1
1/06
04/1
2/06
09/1
2/06
14/1
2/06
19/1
2/06
24/1
2/06
29/1
2/06
03/0
1/07
Data
Rec
alqu
e (m
m)
7080
7085
7090
7095
7100
7105
7110
7115
7120
7125
7130
Esta
ca (m
)
P1P2P3P4P5avanço
Geological model complex but data was fully disclosure no major changes by no means claim based on Different Ground ConditionsCauses are related to shortcomings in engineering processes (design and construction)
systemic fault processLessons and recommendations to engineering and contractual arrangements
Conclusions
Recommendations for Future
Contractual Arrangements
Keep fair balance among quality, schedule and costsMix of technical and performance specifications
quality controlIndependent auditing and full disclosure of control parameters owners must keep controlIncorporate risk management and risk sharing
Pre-Bidding DocumentsGeological and geotechnical data as much as possibleFull disclosure of all GG data
Geological modelGG Data ReportGeotechnical Base Report
Different Ground Conditions Owner
Lessons Learnt
Design DocumentsGeomechanical modelStructural model of the tunnelAssumptions, completeness and type of calculations and simulations
Continuum media?Type of model and parameters2D or 3D analysis?
Monitoring threshold valuesDesign Reviewer
Lessons Learnt
Design during Construction
Complementary investigation and mapping of all GG conditions
Monitoring interpretation
Design back-analysis
Design Validation
Lessons Learnt
ConstructionFaithful to the design changes in agreement
Quality control (materials and services)
Integrated risk and construction management contingency and emergency actions
Lessons Learnt
Role of Contracts
Keep fair balance among quality, schedule and costsMix of technical and performance specifications quality controlIndependent auditing and full disclosure of control parameters
Incorporate risk management and risk sharing
Lessons Learnt
Urban tunnelling is a great and increasing demand worldwideUrban tunnelling is challenging due to urban environment and constraintsUrban tunnelling is likely dominated by limit admissible damage criteriaRisk management has to be incorporated in all project phases
The worst happening is not to have an accident, it is to learn nothing from it.
Kovari, K. & Ramoni. M. (2004). Urban Tunnelling in Soft Ground Using TBMs. International Congress on Mechanised Tunnelling: Challenging Case Histories, Keynote Lecture, Politecnico di Torino, Turin, Italy (www.ita-aites.org).Munich Re (2006). Code of Practice for Risk Management of Tunnel Works: Future Tunnelling Insurance from the Insurer´s Point of View. ITA Open Session, ITA World Tunnel Congress, Seoul, South Korea.Munich Re (2007). Insurance Cover as Part of the General Risk Management Strategy. ITA Open Session on Public Private Partnership Projects, ITA World Tunnel Congress, Prague, Czech Republic.Seidenfuss, T. (2006). Collapses in Tunnelling. Master Thesis, Stuttgart University of Applied Sciences, Stuttgart, Germany, 179 p.