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Sustainable and Resilient Ground Engineering

Sydney July 25 2012

Nick O’Riordan PhD PE CEngDirector/Principal Arup nick.oriordan@arup.com

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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

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MIT Sloan Management Review, January 23, 2012

Interviews with 4000 commercial sector managers in 113 countries

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Urbanisation

Population of Rome Global variations

How much carbon do we emit?TotalPer capita

[Victoria 1230] [NSW 900]

Transition to Low Carbon EconomyNow 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-and-energy-ice-2/

http://wiki.bath.ac.uk/display/ICE/Home+Page;jsessionid=DA1E0CED9CAFCE0A36AB78C5D5A704FE

BSRIA: UK Building Services Research and Information Association

https://www.bsria.co.uk/news/embodied-energy/

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 cap-and-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

After Chester & Horvath(2010) PKT=passenger-km travelled

CapitalCarb

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

....the damage is done

http://www.cahsrblog.com/2010/12/hsr-emissions-paper-was-wrong/

California High Speed Rail

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!

‘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-rail-041712.aspx

New Motorway project payback

0

100,000

200,000

300,000

400,000

500,000

600,00020

1620

1720

1820

1920

2020

2120

2220

2320

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2520

2620

2720

2820

2920

3020

3120

3220

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3520

3620

3720

3820

3920

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CO

2(to

nnes

)

Year

Do Minimum: annual CO2 from use of motorway

Do Something: annual CO2 from use of motorway

Motorway project cumulative CO2

YearDo Minimum

(tonnes/day)

Do Something

(tonnes/day)

2016 359 3262031 419 349

Priority 3 (UK ICE Low Carbon Trajectory)

Like CapEx and OpEx but for carbon

Apply the concepts of CapCarb and OpCarb

CapCarb OpCarb

Materials

Transport

Installation

Maintenance

Usage

Whole Life Carbon

+

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 excludestransport 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 pay-back 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 = 414 GJ (100m2)

52 storey office, Australia = 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

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Carbon in Retaining Walls – steel verses concrete

Sheet Pile Propped Diaphragm 1Propped Diaphragm 2 Diaphragm(Cant)0

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10

15

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25

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Site2 CO2 Emissions of Generic Basement Wall Designs Per Meter Run

CO2

Emiss

ions [

t-CO

2/m

]

SteelConcreteTransportInstallationProp

CO2 emissions /m run10m basement wall (recycled steel)

Sheet pile reuse

Concrete basement wall 400mm Sheet piles extracted

Propped sheet pile

AZ34

Propped diaphragm

800mm

Propped diaphragm 1000mm

Cantilever diaphragm 1500mm

Rented Props and sheet piles

AZ34

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: treatmentmethods

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 becomesEmbankment fill 9800 MJ/ m2300mm sq. driven piles @1.5m c/c 6000 MJ/ m2Tensar 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%.

Seven different alternative design concepts

Concord Community Reuse Plan

Alternative 1

Business-as-usual

Alternative 2

Maximum development

Alternative 5

Concentrated development

SATURN model IMPACT (average speed) CO2 emissions

• Established baseline CO2 for 2008

• Calculate future emissions

Sustainable transport analysis

Mobile source emissions added to stationary source emissions and normalized across the service population

ALT 1 Business-as-Usual

ALT 2 Maximum build-

out of site

ALT 5 Concentrated

, transit-oriented

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

Concord Community Reuse Plan

24km long; dual 3-lane motorway •2 major interchanges; •29 structures

New motorway Carbon comparison

CO2 by construction element

Structures (including foundations)

Pavement

Earthworks

Operational CO2 (over 40 years) (tonnes)

Construction CO2 (tonnes)

Structures incl foundations

Pavement

Earthworks

Effect of vertical profile/alignment

Tunnel vs Bridge

“Long Tunnel” “Long Bridge”

Low gradient: low Op Carb High gradient: high Op Carb

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.

 

Sustainability and Resilience

Sendai airport, Miyagi prefecture, NE Japan

Tsunami from Tohoku earthquake March 11 2011

September 11 2011

June 3 2011

Design for resilience

http://blogs.sacbee.com/photos/2011/09/japan-marks-6-months-since-ear.html

Repairable Limit State

After Honjo (2010)After SEAOC (1995)

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

Soga & Chau (2006)

x10

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

Electrical – Gas - Water Utility Plan

E EW G

E

Utility evaluation and resilience, urban centers/CBD

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

Analysis 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

Extracting 30W/m2Peak summer temp in tunnel is 36 degrees

Geothermal piles

Lambeth College thermal pile load test

Bourne-Webb et al (2009) Energy pile test at Lambeth College

LS-DYNA model

23m

Top 6m of pile has diameter 610mm

4m

Remainder of pile has diameter 550mm

5m

Model input dataLoad 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.

3. Reload to 1.2MN

2. Unload

1. Load to 1.8MN

Result – settlement vs timeSettlement 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.

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

Cooling Heating

Result – pile strain distribution vs test

For compatibility with the published test results, thermal strains have been subtracted leaving only the mechanical (stress-inducing) strains.

During heating

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

After Pantelidou et al (2012)

Vehicle/structure characteristicsSupply chain

Define repairable limit stateMinimise 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

http://www.americanlifelinesalliance.com

..it is the greatest happiness of the greatest number that is the measure of right and wrong

A Fragment on Government, Jeremy Bentham, 1776