Presentation - Australian Geomechanics Society

Report
Sustainable and Resilient Ground
Engineering
Nick O’Riordan PhD PE CEng
Director/Principal
Arup
[email protected]
1
Sydney July 25 2012
Sustainable and resilient Ground Engineering
•Context
•Embodied energy
•Capital carbon investment and operations & maintenance carbon
•Sustainability and resilience
•Repairable limit states
•Co-located infrastructure: making best use of invested carbon
2
MIT Sloan Management Review, January 23, 2012
3
Interviews with 4000 commercial sector managers in 113 countries
Urbanisation
Population of Rome
4
Global variations
How much carbon do we emit?
[Victoria 1230]
[NSW
900]
Per capita
Total
Transition to Low Carbon Economy
Now a Legal Obligation in UK: Climate Change Act 2008
Reduction of carbon emissions on the 1990 levels
- 26% by 2020
- 80% by 2050
Carbon budgeting system – cap emissions over 5 year periods
Sustainable and resilient Ground Engineering
If not us, then who?
New EuroNorms: Sustainability of construction
works
BS EN 15643-1:2010 Sustainability assessment of buildings: Part
1: General framework
BS EN 15643-2:2011 Assessment of buildings: Part 2:
Framework for the assessment of environmental performance
BS EN 15978:2011 Assessment of environmental performance of
buildings-Calculation method
None of these standards relate to geotechnical systems, and none define what is
an acceptable Cap Carb investment payback period
Embodied Energy (EE)
is the total energy that can be attributed towards shaping a
product to its current state
includes energy consumed in winning raw materials, processing
and manufacturing products from them in a project-specific
way
for Infrastructure works, EE enables different methods of
construction/product delivery to be compared (e.g. sheet pile
wall or concrete diaphragm/slurry wall or CDSM + soldier
pile wall+permanent reinforced concrete box?)
enables fuel choices (and hence CO2 emission impact) to be made
enables construction plant utilisation/efficiency to be evaluated
Inventory of Carbon and Energy (ICE)
University of Bath, UK
http://www.amee.com/blog/2011/08/01/inventory-of-carbon-andenergy-ice-2/
http://wiki.bath.ac.uk/display/ICE/Home+Page;
jsessionid=DA1E0CED9CAFCE0A36AB78C5
D5A704FE
https://www.bsria.co.uk/news/embodiedenergy/
BSRIA: UK Building Services Research and Information Association
CO2 emission factors (kg/kWh generated in UK)
Natural Gas
0.19
Diesel
0.25
LPG
0.21
Wind
0.00
CO2 emission intensities
(kg/tonne)
•Granite ballast at quarry gate
1.1
•Pulverised fuel ash
2.1
•Portland cement (non-renewable power source)
1000.0
1GJ = 0.06 to 0.1 tonne CO2
California is ahead of the other states…but like
Australia (and maybe Britain) has chosen capand-trade rather than control consumption
First litigation challenge to AB 32 (the Global Warming
Solutions Act) and the cap-and-trade program in
Association of Irritated Residents, et al. v. California Air
Resources Board, Case No. CPF-09-509562, ("Ass'n of
Irritated Residents v. CARB "). Though environmental justice
groups continue to object to cap-and-trade as the primary
vehicle to reduce greenhouse ("GHG") emissions to 1990
levels by 2020, the California Supreme Court recently allowed
California Air Resources Board's (“CARB") cap-and-trade
implementation to move forward, and agency rule
development continues.
National Law Review October 2011
California High Speed Rail: Life Cycle Assessment
Capital
Carb
After Chester & Horvath(2010)
PKT=passenger-km travelled
Once it’s out there......
Original outcome: why build an
expensive railway if there is
marginal reduction in GHG
emissions compared to car or
airplane?
Corrected outcome: even a HSR
train that is only 10% full is
greener than driving, or a half-full
airplane
http://www.cahsrblog.com/2010/12/hsremissions-paper-was-wrong/
....the damage is done
California High Speed Rail
‘construction and operation of the system would emit
more GHG emissions than it would reduce for
approximately the first 30 years’
California Legislative Analysts Office, April 17, 2012.
http://www.lao.ca.gov/analysis/2012/transportation/high-speed-rail041712.aspx
However Chang & Kendall (2011)
show around 8 years payback period
Is a CO2 payback period of 8 years acceptable, politically, socially,
financially? Clearly 30 years is not!
New Motorway project payback
Do Minimum
Do Something
(tonnes/day)
(tonnes/day)
359
419
326
349
Year
2016
2031
600,000
Do Minimum:
annual CO2 from
use of motorway
500,000
Do Something:
annual CO2 from
use of motorway
300,000
Motorway project
cumulative CO2
200,000
100,000
0
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
CO2 (tonnes)
400,000
Year
Like CapEx and OpEx but for carbon
Apply the concepts of CapCarb and OpCarb
Materials
Transport
Maintenance
CapCarb
+
OpCarb
Installation
Usage
Whole Life Carbon
Priority 3 (UK ICE Low Carbon Trajectory)
Detailed high speed rail comparison
•Piled slab, 11 km in total length, very soft ground
approx 10 to 12m thick
•Chosen for ride quality stability/ predictability
•Embankment solution would have required either
embankments 4.5m thick and vertical drains or thinner
embankments with ground strengthening (DDSM, CMC
etc)
•Was piled solution the best, from an energy efficiency
standpoint?
Piled slab: 11 km (7 miles) length, Channel Tunnel Rail Link
project, very soft soils: Thames Marshes, UK
Material Embodied Energy intensity (MJ/kg)
for CTRL piled slab v embankment comparison
Ballast* and sub-ballast
1
Compacted fill
0.7
Virgin Steel
55
Recycled Steel
10
Concrete
2
Diesel
36
density of concrete
2240
kg/m3
density of steel
7840
Kg/m3
*Includes 100 km round trip from stockpile, but excludes
transport from quarry
CTRL 310 piled slab - Assumption and boundaries
(after Chau et al, 2012)
Boundaries
- Linear site (11.3km) and time ( 2 years)
- CTRL contract 310 excluding viaducts, bridges, electrifications
- Just construction, exclude operation, maintenance and some preliminary
enablement works
- Exclusion of manual labours, and associated travel
- As-built records give duration and utilisation of plant
- Ballast from stockpile (100 km round trip), quarry to stockpile excluded
Assembly of machineries NOT included
- machine energy insignificant? Yet to be evaluated.
- Reuse of machines, not just for one project.
Hypothetical embankment alternative
- 4.5m thick, to give required dynamic behaviour on very soft ground
- ground improvement to achieve 2 year construction
- excludes bridge/viaduct transitions
CTRL Contract 310, high speed rail on piled slab:
very soft soils
After Chau et al (2012), 4.5m total embankment thickness
EE of ballast transport from quarry excluded
For new-build rail in the UK, ballast is a significant
component in terms of EE and CO2
For new-build, structural solutions including
slabtrack appear more efficient and
‘sustainable’
Can a ‘sustainable’ case be made for
progressive replacement of ballasted
track with slabtrack?
Slab track v ballasted track:
Is received wisdom from the Shinkansen (the bullet train) truly
correct?
‘Paved track is up to 1.3 times more expensive to install
but significantly reduced maintenance results in payback in 9 years…’
IEEP (2006) for RMT Parliamentary Group Seminar ‘The Sustainable Case for Rail’
Slabtrack:
WCML Crewe -Kidsgrove
EE comparison for ballasted v slabtrack
•EE ballasted track maintenance=0.8 TJ/km
•Total EE of unoptimised slabtrack = 20 TJ/km
•Total EE of piled slab excluding ballast = 30TJ/km
•CO2 emissions for ballasted track maintenance = 50 tonnes/route km
•Total CO2 emissions for new slabtrack =
1,000 tonnes /km
•‘Payback period’ for new slabtrack versus ballasted track maintenance = 20 years
For new build railways in the UK, ballast is a
significant component in terms of EE and CO2
Structural solutions including slabtrack
appear more efficient and ‘sustainable’ than
ballasted track
After Kaini et al, 2008)
Embodied Energy relationships
(after Workman & Soga, 2004 and DTI, 2000)
UK masonry house
52 storey office, Australia
= 414 GJ (100m2)
= 2590 TJ (130000m2)
High Speed 1 Stratford>St Pancras UK
Twin bored tunnel, 11 km
= 900 TJ (construction only)
1 GJ=277.8 kWh
Coal fired power= c.7500 kWh/tonne
LPG = 13722 kWh/tonne
Wood = c.3000 kWh/tonne
Tyres = 8888 kWh/tonne
Retaining walls: basic process &
EE intensities
Carbon in Retaining
Walls
steelWallverses
concrete
Site2 CO Emissions
of Generic–Basement
Designs Per Meter
Run
2
30
CO2 emissions /m run
10m basement wall
(recycled steel)
sheet piles
AZ34
25
CO2 Emissions [t-CO2/m]
Concrete
basement
wall 400mm
Sheet piles
Rented
extracted
Props and
Sheet pile reuse
30
Cantilever
diaphragm
1500mm
20
Propped
diaphragm
800mm
15
Propped
diaphragm
1000mm
Propped
sheet pile
AZ34
10
5
0
Sheet Pile
Propped Diaphragm 1Propped Diaphragm 2 Diaphragm(Cant)
Steel
Concrete
Transport
Installation
Prop
Embankments on soft clay:
Speed v certainty
Very soft clays: design parameters difficult to determine without
trials
Greater certainty by modifying soil behaviour/ load pathways and
load magnitude
Embankments on soft ground: treatment
methods
DDSM/
After O’Riordan & Seaman (1994)
Some Embodied Energy intensity values for soft
ground engineering
Component
EEI value*
Driven 300mm PC pile, 10m
long, 2 tonne
6GJ/pile
DDSM @ 100 kg/m3 OPC from
gas-fired power station
energy source, 10m deep,
90 % coverage,
10GJ/ m2
Vertical, 100mm wide
Prefabricated drain, 10m
deep @1m c/c
1.5 MJ/ m2
Geogrid such as Tensar SS40
@ 0.53 kg/m2
40 MJ/ m2
11 tonne truck, average daily
running speed =50 km/hr
2 MJ/km (pro-rata for lower daily running
speeds)
* Excludes EE associated with transport of component to site
9m thick embankment, 2m settlement, with
vertical drains @ 1m c/c
Embankment fill
12600 MJ/ m2
Vertical drains
1.5 MJ/ m2
Geogrid
40 MJ/ m2
If the 2m settlement, and the associated time for consolidation can be avoided using BASP
piling, the comparable EE becomes
Embankment fill
9800 MJ/ m2
300mm sq. driven piles @1.5m c/c
6000 MJ/ m2
Tensar geogrid
40 MJ/ m2
TOTAL 15840
DDSM solution would be a further 5000 MJ/m2 above BASP
After O’Riordan (2006)
Embodied energy, CO2 footprinting and
construction on soft ground
Current solutions are often driven by speed of construction and/or
the need for certainty of outcome
Embodied energy calculations can enable the selected solution to
be put into the wider project context, to become part of the
overall environmental drivers for a given scheme
For example, a road bypass will have the effect of reducing local
CO2 emissions by X tonnes/year, and the associated
construction emissions are Y%.
Concord Community Reuse
Plan
Seven different alternative design concepts
Alternative 1
Alternative 2
Alternative 5
Business-as-usual
Maximum development
Concentrated
development
Sustainable transport analysis
• Established
baseline CO2 for 2008
• Calculate future emissions
SATURN model
IMPACT (average speed)
CO2 emissions
Concord Community Reuse
Plan
Mobile source emissions added to stationary source emissions and
normalized across the service population
ALT 1
ALT 2
Business- Maximum buildas-Usual
out of site
ALT 5
Concentrated
, transitoriented
development
Regional mobile emissions over No
Project
95,208
145,766
52,446
Stationary emissions (TCO2e)
400,470
457,074
350,028
Total gross emissions (TCO2e)
495,678
602,840
402,474
Service population (residents + jobs)
39,200
59,600
45,800
GHG efficiency rate (TCO2e/person)
12.6
10.1
8.8
New motorway Carbon comparison
24km long; dual 3-lane motorway
•2 major interchanges;
•29 structures
CO2 by construction element
Earthworks
Structures (including
foundations)
Pavement
Structures
incl foundations
Pavement
Earthworks
Effect of vertical profile/alignment
Tunnel vs Bridge
“Long Tunnel”
Low gradient: low Op Carb High gradient: high Op Carb
“Long Bridge”
Sustainability and Resilience
 Sustainability: ‘(an attribute of an activity or thing) that meets
the needs of the present without compromising the ability of
future generations to meet their own needs’, after Brundtland. So
this requires a look ahead towards higher/older population densities, developments in technology, and a desire to ensure that
chosen activities do not deplete resources significantly.
 Resilience: the ability of a thing to return to its original shape
and function. Something is not resilient if a lot of effort is required to return it to its original shape and function. So
earthquake code writers in California have chosen to prevent collapse of structures, for example, and admit that irreparable
damage may occur requiring demolition and replacement. This requires less investment (both carbon-based and money-based)
than a more resilient approach. There are exceptions, in particular, at Caltrans where the foundation system is capacity protected and the
superstructure has defined strain limits at both Safety Evaluation and Functional Evaluation levels. In the Caltrans case, careful balancing of cost and
selected return period is required. I would say that Caltrans’ approach is resilient, however it is ‘sustainable’ only if the carbon emission budget is
identified and optimized. Interestingly there is a trend towards ‘monopile’ foundations which are analytically simple to design but will tend to use
larger quantities of high greenhouse gas emitters like concrete and steel than an equivalent multiple pile group.

Design for resilience
Tsunami from Tohoku earthquake
March 11 2011
Sendai airport, Miyagi
prefecture, NE Japan
June 3 2011
September 11 2011
http://blogs.sacbee.com/photos/2011/09/japan-marks-6-months-sinceear.html
Repairable Limit State
After SEAOC (1995)
After Honjo (2010)
 ULS (Life Safety) and SLS(Fully Functional)
limit states rarely coincide
 Increasingly often, the SLS is the governing
load/resistance system, but this costs $$$ and
CO2
 Can we achieve savings by identifying a
Repairable Limit State that is economically
acceptable, and which provides adequate safety
at ULS?
 We have examples with highway and railway
feedback and maintenance systems
 We can do better!
Smarter analyses: piled foundations in karst
Coastal protection assessment, Monterey Bay CA
Comparison of probability of failure during design earthquake,
and EE of selected solution
x10
Soga & Chau (2006)
Resilent foundations/capacity protection
Design (SEE) earthquake
- 5% probability of exceedance in 50 years from PSHA
(t = 975 yr)
Cable tower:
- Designed as ductile member
Cable design:
- Design for cable replacement
- Design for cable loss
Displacement control:
Cover damaged joints with steel plates
post-earthquake
Caltrans and monopiles
Carbon footprint of 4m dia. monopile = 20 No 1m dia.CIDH piles
Utility evaluation and resilience, urban centers/CBD
Transbay Transit Center, San Francisco
Utility evaluation and resilience, urban centers/CBD
Electrical – Gas - Water Utility Plan
E W
G
E
E
Utility evaluation and resilience, urban centers/CBD
3.0 s :
first mode period of structure
Soil-Structure Interaction, Analysis Model
Bus Ramp
TTC Superstructure
TTC Trainbox
Tiedowns
Soil Domain
Ground Motion
Wet Utility Flexible Joint
Multi-functional, co-located buried infrastructure
Natural temperature gradients at shallow depth
Pile test site at Monash Uni, Clayton, after Wang et al (2012)
Geothermal modelling and feedback systems
Peak summer temp in
tunnel is 36 degrees
Analysis
Extracting 30W/m2
Hoop stress (MPa)
Tensile Stress (MPa)
Winter Summer
Winter
Summer
‘Normal design’ in LC
10.4
10.4
2.0
2.0
0W extraction
11.4
12.6
3.1
3.4
30W extraction
12.9
13.5
3.1
3.5
Geothermal piles
Lambeth College thermal pile
load test
Bourne-Webb et al (2009) Energy pile test at
Lambeth College
LS-DYNA model
23m
5m
4m
Top 6m of pile
has diameter
610mm
Remainder of pile
has diameter
550mm
Model input data
Load on pile. Graph shows equivalent load for a whole pile (the load in the model is a
quarter of this value). The test pile was loaded to 1.8MN, unloaded, then loaded to
1.2MN. The load was held constant for the remainder of the test.
1. Load to 1.8MN
3. Reload to 1.2MN
2. Unload
Result – settlement vs time
Settlement prediction
matches test well during
the cooling phase, when
the pile shrinks down into
the ground.
During the heating phase,
the model predicts that two
thirds of the previous
settlement will be
recovered as the pile
expands, but the test result
shows that only one third
is recovered.
Cooling
Heating
If the top of the pile were
prevented from expanding
upwards, that would be
consistent with the strain
measurements that suggest
an increase of applied load
during the heating phase.
Model: /data3/rsturt/ENERGY_PILES/LAMBETH_JAN2012/RUN17_TDC/Lambeth_17_TDC.key
Result – pile strain distribution vs test
During heating
For compatibility with the
published test results,
thermal strains have been
subtracted leaving only the
mechanical (stressinducing) strains.
Comment:
Test result
measurements appear to
be influenced by head
restraint. In the
experiment, the load at
the top of the pile was
held constant
Model: /data3/rsturt/ENERGY_PILES/LAMBETH_JAN2012/RUN17_TDC/Lambeth_17_TDC.key
Sustainable ground engineering: ability to
influence outcome during a project lifetime
Vehicle/structure
characteristics
Supply chain
After Pantelidou et al (2012)
Define repairable limit
state
Minimise waste
Summary
• Need to understand ‘business-as-usual’/Do Nothing in detail
• Need to consider Cap Carb and Op Carb
• For Transport projects involving high speed trains and/or
freight movements, this means shallow gradients and more
tunneling.
• What is an acceptable Cap Carb payback period if we Do
Something?
• Relationship between resilience and sustainability: design for
‘repairability’?
• Co-located infrastructure: geothermal tunnels and piles
• Greater influence if involved early in the project lifetime
Sustainable and resilient Ground Engineering
If not us, then who?
If not now, then when?
Thank you
An uncertain future
..it is the greatest happiness of the greatest number that is
the measure of right and wrong
A Fragment on Government, Jeremy Bentham, 1776
http://www.americanlifelinesalliance.com

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