simon abbott professional head of geotechnics
TRANSCRIPT
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DESTinationRAIL, 26-27 April 2018, University of Zagreb
Simon Abbott – Professional Head of Geotechnics [email protected]
Experiences of Earthwork Management
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Risk definition
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Risk = Likelihood x Consequence
Con
seq
uen
ce
of ris
k e
ven
t
5
4
3
2
1
A B C D E
Likelihood of risk event
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TOP GEOTECHNICAL CHALLENGE Detection of asset failure by
means other than train drivers
£3m remote failure detection pilot looking at
rapid failure of soil cuttings
Risk Bow Tie, Tech Roadmap & Challenge Statement
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WCM1 in Scotland: November 2015
Example: Significant Event (failure) 50+
F
F
A
I
L
E
D
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Western: Kemble (Jan 17)
Wessex: Milborne (Mar 16) Scotland: Murthat (Nov 15)
LNW: Watford (Sept 16)
Further examples of notable events
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Organisation Roles and Responsibilities (Simplified !)
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Safety, Technical & Engineering Route Businesses
Technical authority and assurance body. Set the overall
direction and corporate strategies for safety, environment,
asset management and engineering. Owner of asset policies,
risk control frameworks and the innovation / R&D pipelines.
Owner of route assets with day to day accountability for the
safe management of the infrastructure. Plan and deliver
inspections, maintenance and renewals of assets in line with
corporate policies to achieve agreed objectives.
Prof Head of Structures
Prof Head of Tunnels & Mining
Prof Head of Drainage
Prof Head of Buildings
Capability Groups
- Principal Engineers
- Senior Engineers
- Engineers
Prof Head of Geotechnics
Director(s) of Route Safety
and Asset Management
Route Asset Manager(s)
(Discipline Specific)
- Senior Asset Engineers
- Asset Engineers
- Assistant Asset Engineers
Route Managing Director(s) Chief Engineer
Chief Civil Engineer
MD of Route Businesses Group Director of STE Director of Digital Rail Managing Director of IP CEO
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Capital investment improves safety, reliability and weather resilience BUT legacy issues relating to knowledge at the time of construction
will continue to be a root cause in many earthwork failures
RELATIVE
PRIORITISATION
– targeted investment to manage
network risk. Pro-active and
sustainable asset management
RELIABILITY – justified intervention and
investment from targeted monitoring to
prevent failing assets impacting operations
FORECASTING
DETERIORATION
Relative prioritisation requires informed decision making
with competent staff, effective tools and processes
RECOVERY – reactive restoration FAILURE IMPACTS ON UK PLC
FUTURE
PROOF
FAILING ASSETS
RESISTENCE (& resilience)
TO WEATHER - quantifying
challenge to industry.
Multi-control period
journey to achieve
Big Data
Collection &
Management
Strategic &
Tactical Models
Analytics &
Algorithms
Data Cleaning
& Validation
Continuous
Improvement
OUR KEY DRIVER
IN RESPONSE
Global Stability Resilience
Appraisal (GSRA) completed
2017 – quantifies threat from
legacy construction issues
Core activities
today using
Earthworks
Safety Risk
Matrix in pro-
active asset
management
Strategic long term journey
to address gap in weather
resilience – rate of change
relative to appetite and
availability of funding
CHALLENGES IN
MANAGING EARTHWORKS
Preventative (predict)
Preventative
(pre-determined)
Maintaining Reliability
Improving Reliability
Broader NR
terminology in
maintenance
effectiveness
Corrective
Earthworks: Challenges and Key Drivers in Response
DE
CR
EA
SIN
G
DA
TA
VO
LU
ME
& I
NC
RE
AS
ING
D
AT
A V
AL
UE
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• Control Period spend for CP5 forecast outturn of £680m. Strategic Business Plan (SBP) recently published
shows a total of £793 for CP6 (17% increase)
• Three asset types each with unique challenges:
• embankments provide biggest performance challenge (accounting for up to 8% of TSRs per period)
• soil and rock cuttings provide greatest safety risk and continue to cause significant events
Long term improvements becoming apparent, with
safety events reducing particularly from cuttings.
However, inherent legacy construction issues will
always provide challenges for weather resilience
(or resistance)
A high level overview of management and safety performance
Continuous improvement over
the last 20 years in a range of
areas including:
• Staff numbers & competence
• Policy
• Asset management
• Inventory database
• Weather management
• Strategic planning
• Work bank management
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Individual topics I could talk about in great detail today….
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Natural slopes in lower consequence locations (Loch Eilt)
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February 2013
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Winter 13/14 – DfT review commissioned
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Bradwell Abbey - LNW (October 2013)
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Improving problematic cuttings
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Preparatory Condition of Asset Base
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PROBABILITY
UN
CE
RT
AIN
TY
Increasing chance of occurrence
0 1.0
From: Lee, E.M 2009. Landslide Risk Assessment. QJEG, Vol 42, p445-458.
A Brief Timeline
1. 1995 – Fatality at Ais Gil landslip
2. British Rail – Soil Mechanics
Division sold off. Maintenance
gangs with local knowledge
dispersed following privatisation
3. Early 2000’s – recruitment of first
specialist Area / Territory
geotechnical engineers
4. 2001/02 – Earthwork TSR reporting
commenced
5. 2003/04 – Earthwork volume
reporting commenced
6. 2004/05 – Earthwork Failure
reporting commenced
7. 2005/06 – Electronic data capture
of defects commenced during
earthwork inspections
8. 2012 – Asset specific Earthwork
Policy Issued for the first time
9. 2014/15 – Evidence based
statistical examination system
deployed into business
10. 2016 – Asset inventory complete
Inc
rea
sin
g e
xp
loita
tion
of k
no
wle
dg
e a
nd
eva
lua
tion
of ris
k
Probability / Uncertainty / Confidence
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Geotechnical Asset Definitions
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NR/L3/CIV/065: Examination of Earthworks
Capturing Earthwork Asset Information
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Typical Defects and Movement Indicators
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SSHI
29 7-Jul-15
• Put in place in NW Zone in 1997 (Post Ais Gill)
• 2001 review recommended national use (as
basis for first 065 standard)
• Systematic examination of observed parameters
• Based around 5 failure modes (Rotational,
Translational, Earthflow, washout and burrowing)
• Potential and Actual failure indicators
• Parameter weighting by expert judgement:
• 16 possible SSHI scores
• Serviceable, Marginal and Poor categorisation
(banding of 16 scores). Emotive terminology.
• REM (subjective assessment) used to adjust
SSHI weightings
• Refs: Manley and Harding, 2003, Babtie, 2004
Soil Slope Hazard Index (SSHI)
/ 7-Jul-15 30
Clarborough: 27th April Loch Treig: 26th June Rosyth: 18th July
Bargoed: 30th January St Bees: 30th August Barrow: 27th December
Enforcement action in 2012/13
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Wettest Winter on Record – 2013/2014
7-Jul-15 31
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Improvements in assessing safety risk
to this from this
FURTHER INFO SEE:
Power, C., Mian, J., Spink, T., Abbott, S., Edwards, M.
(2016). Development of an Evidence-based
Geotechnical Asset management Policy for Network
Rail, Great Britain. The 3rd International Conference on
Transportation Geotechnics. Procedia Engineering.
Volume 143, p.726-733.
Catalyst for improvement came from events of 2012/13
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Risk definition
33
Risk = Likelihood x Consequence
Con
seq
uen
ce
of ris
k e
ven
t
5
4
3
2
1
A B C D E
Likelihood of risk event
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Geotechnical assessment
Severity of impact
Consequence – safety impact
34
Earthwork
failure
Debris on
track or track
undermined
Track not
affected
Train
derails
No
derailment
Collision with
another train
Train falls down
embankment
Collision with
obstacle
Rapid
deceleration
Emergency stop
Controlled
incident
Incre
asin
g s
eve
rity
Fatalities &
Weighted
Injuries (FWI)
1.0 Fatality
10 Major injuries
200 Minor
injuries/major shock
1,000 Non
reportable minor
injuries/minor shock
Asset Criticality
Score
Earthwork Asset
Criticality Band
(EACB)
/ 7-Jul-15 35
0
10
20
30
40
WholePopulation
Failures
% O
cc
urr
en
ce
0
5
10
15
20
WholePopulation
Failures
% O
cc
urr
en
ce
e.g. Slope angle < 15 deg and height < 3m
e.g. Slope angle > 35 deg and height > 10m
Negatively
weighted
parameter
Positively
weighted
parameter
All ~200
parameter
values
Total
Hazard
Index
Split into 5
Earthwork
Hazard
Categories
SCHI and SEHI Analysis Process
Earthworks Hazard Category
• Statistical likelihood of failure
• 2 orders of magnitude range for SEHI and SCHI
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Predicting failure
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0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
A B C D E
Per
cen
tage
dis
trib
uti
on
of
asse
ts/f
ailu
res
EHC Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution
Asset distribution
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Predicting failure
37
Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution
0
20
40
60
80
100
120
140
160
180
200
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
A B C D E
No
rmal
ised
pro
bab
ility
of f
ailu
re
Per
cen
tage
dis
trib
uti
on
of
asse
ts/f
ailu
res
EHC Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution
Asset distribution Normalised probability of failure
/
0
20
40
60
80
100
120
140
160
180
200
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
A B C D E
No
rmal
ised
pro
bab
ility
of f
ailu
re
Per
cen
tage
dis
trib
uti
on
of
asse
ts/f
ailu
res
EHC Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution
Predicting failure
38
Asset distribution Normalised probability of failure Failed asset distribution
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Preliminary Assessment
of Slope Stability
(capability)
4-May-18 39
The legacy threat
A pragmatic approach today
Acquisition of better data Assessment of slope stability
Continuous Improvement – quantifying the legacy threat
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National Aerial Survey
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National Aerial Survey
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0
2
4
6
8
10
12
14
16
18
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00.511.522.533.544.555.566.577.58
Slo
pe
hei
ght
(m)
Slope angle (Cot B)
Deep-seated stability chart - Cuttings - D4 - High to Highest Drainage
Cross Asset Risk
All Assets Upper bound Lower bound
Global Stability Resilience Appraisal (GSRA)
42
1
cotB
B
Low
vulnerability
Moderate
vulnerability
High
vulnerability
High plasticity clays – Deep seated failure – High pore water pressure
11° 14° 18° 27° 45°
Stability chart
boundaries vary with: • Geology
• Failure mode
• Pore pressure conditions
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0
2
4
6
8
10
12
14
16
18
20
00.511.522.533.544.555.566.577.58
Slo
pe
hei
ght
(m)
Slope angle (Cot B)
Deep-seated stability chart - Cuttings - D4 - High to Highest Drainage
Cross Asset Risk
All Assets Failed Assets Upper bound Lower bound
43
1
cotB
B
Low
vulnerability
Moderate
vulnerability
High
vulnerability
High plasticity clays – Deep seated failure – High pore water pressure
11° 14° 18° 27° 45°
Stability chart
boundaries vary with: • Geology
• Failure mode
• Pore pressure conditions
Failures mainly in high
vulnerability
Global Stability Resilience Appraisal (GSRA)
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0
2
4
6
8
10
12
14
16
18
20
00.511.522.533.544.555.566.577.58
Slo
pe
hei
ght
(m)
Slope angle (Cot B)
Deep-seated stability chart - Cuttings - D4 - High to Highest Drainage
Cross Asset Risk
EHC A assets EHC B assets EHC C assets EHC D assets
EHC E assets Upper bound Lower bound
44
1
cotB
B
Low
vulnerability
Moderate
vulnerability
High
vulnerability
High plasticity clays – Deep seated failure – High pore water pressure
11° 14° 18° 27° 45°
Stability chart
boundaries vary with: • Geology
• Failure mode
• Pore pressure conditions
Failures mainly in high
vulnerability
FoS & condition poorly
aligned • Failure vs precursors
• Progressive failure
• Extreme weather events
• Degradation rates vs
inspection interval
Global Stability Resilience Appraisal (GSRA)
/
0
2
4
6
8
10
12
14
16
18
20
00.511.522.533.544.555.566.577.58
Slo
pe
hei
ght
(m)
Slope angle (Cot B)
Deep-seated stability chart - Cuttings - D4 - High to Highest Drainage
Cross Asset Risk
EHC A assets EHC B assets EHC C assets EHC D assets
EHC E assets Upper bound Lower bound
45
1
cotB
B
Stability chart
boundaries vary with: • Geology
• Failure mode
• Pore pressure conditions
Failures mainly in high
vulnerability
FoS & condition poorly
aligned • Failure vs precursors
• Progressive failure
• Extreme weather events
• Degradation rates vs
inspection interval
Challenges: • Combined approach to
improve predictability
• Historic interventions
• Vegetation impact
Low
vulnerability
Moderate
vulnerability
High
vulnerability
High plasticity clays – Deep seated failure – High pore water pressure
11° 14° 18° 27° 45°
Global Stability Resilience Appraisal (GSRA)
/
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Presentation Title: View > Header & Footer 46
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Better exploitation of track data to identify problems
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• Earthwork examination algorithm; an evidenced based statistical
approach to quantifying the annual failure probability
• Parametric study undertaken to calibrate parameters against the
earthwork failure records
Actionable limits for track
Improvements could be made to existing processes if statistical evidence demonstrates the predictive
capabilities in the identification of previously failed embankment assets over and above non-failed assets
The challenge is to demonstrate that false positives are not continuously flagged out for evaluation.
Parametric study to consider:
• Failed embankment data set
• Sub-surface monitoring sites that
show failure is taking place
• Earthwork hazard categories
• Capital investment plans
Not always treating the root cause
Recipe Algorithm
Rich source of data
Continuous improvement in understanding deterioration
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11th August 2016
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Winter Failures
0
20
40
60
80
100
120
140
160
0.00% 50.00% 100.00% 150.00% 200.00%
Win
ter
Eart
hw
ork
Failu
res
Winter Rainfall (% LTA)
Winters (Dec-Feb)
13/14
15/16
/
Approach to Weather Trigger Levels
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% SEVERITY VALUES
Rain
fall
Se
ve
rity
(%
)
SMI Severity (%)
Define zones around the failures cluster to correspond to Normal, Alert,
Adverse, Extreme weather.
Normal
Alert
Alert
Adverse
Extreme
Correlating Weather to Earthwork Failures
► Ongoing work….challenging and no utopian position
► Historical SMD trends poor…..new approaches use SMI and Rainfall
/
Selecting boundaries
► Picking thresholds has to achieve a balance
► Requires routes to but into operational impact
4-May-18 55
TRADE OFF
More weather
warnings
Few failures in
‘Normal’ weather
More ‘Normal’
weather
Many failures in
‘Normal’ weather
Low
thresholds
High
thresholds
► Trialled 40 different combinations to achieve the best overall balance.
► Starting point / aims:
∙ 85% Normal Weather frequency
∙ 3-7% Adverse Weather frequency
∙ 1-2% Extreme Weather frequency
Correlating Weather to Earthwork Failures
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Pursuit of opportunity to detect failures before trains
TOP GEOTECHNICAL CHALLENGE Detection of asset failure by
means other than train drivers
Tilt-meters Pilot
Study & further roll
out to soil cuttings
TECH 9
TRL: 7 IRL:tbc
££
£3m Pilot study is still within the roll-out phase of deploying
instrumentation to 180 assets (0.09% of the asset base).
/ Presentation Title: View > Header & Footer 57
Summary and conclusions
• Reducing number of potentially high consequence earthwork failures is the result of continuous
improvement, the introduction of an asset specific policy and an increase in staffing numbers of
engineers managing the portfolio.
• Climate change and increased demand for greater usage on the network will provide longer term
risks for which we shall continue to work with academia and research groups to further our knowledge
and understanding. Asset degradation is starting to be understood with greater confidence.
• It is recognised that continued capital investment is required to progressively strengthen our
infrastructure slopes. The rate of this investment will depend on the needs of other asset groups and the
difficult decisions that are continually made for the benefit of the whole railway system. Various criteria
need to be considered for the optimum trade-off between cost, risk and performance.
• Stopping trains from finding failed earthworks that have rapidly lost the ability to perform is our
top geotechnical challenge. We recognise that we have to improve our mitigations to reduce the
consequence of asset failure once it has occurred. The rapid failure of soil cutting slopes across of
infrastructure is difficult to predict and the acceleration of deformation is often the result of local rainfall
events that can be difficult for meteorologists to accurately predict with suitable confidence.
• We do not know what the technology of tomorrow will be but we recognise we must embrace
innovation, horizon scan and invest appropriately in R&D. Simultaneously continued capital
investment is required to progressively strengthen the portfolio at a proportional rate to meet the varying
demands across the network.
/
Mellor, R. et al. in review. Development of a Global Stability and Resilience Appraisal for Network Rail earthwork assets.
Quarterly Journal of Engineering Geology and Hydrogeology.
Merrylees, C. in review. Improving the understanding of weather drivers of earthwork failures along Britain’s rail network: a
data driven approach. Quarterly Journal of Engineering Geology and Hydrogeology.
Office of Rail Regulation, Arup & Network Rail. 2011. Part A Reporter mandate AO/007: review asset policy, stewardship and
management of structures. Final report – Review and benchmarking Available via hyperlink
Office of Rail Regulation, Arup & Network Rail. 2015. Part A Reporter mandate AO/049: review of updated earthworks asset
policy for CP5 years 3-5 Available via hyperlink
Power, C. et al. 2016. Development of an evidence-based geotechnical asset management policy for Network Rail, Great
Britain. Procedia Engineering 143: 726–733, Available via hyperlink
Presentations from 2017 Conference Ground Related Risk to Transportation Infrastructure, including keynote on “Strategic
geotechnical asset management challenges”, Available via hyperlink
4-May-18 58
Further Information
Network Rail Earthworks Technical
Strategy (left) will shortly be available
online, together with our challenge
statements that are published on our
website and are available via hyperlink
We are always keen to hear from the
supply chain to assist in the development
of ideas, solutions and products. Please
do get in touch and if your idea or
proposal sparks interest we will invite
you in to present to our engineers in
Milton Keynes R&[email protected]
/ 4-May-18 59
Thank you