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1 Sustainable and Resilient Ground Engineering Sydney July 25 2012 Nick O’Riordan PhD PE CEng Director/Principal Arup

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Presentation on theme: "1 Sustainable and Resilient Ground Engineering Sydney July 25 2012 Nick O’Riordan PhD PE CEng Director/Principal Arup"— Presentation transcript:

1 1 Sustainable and Resilient Ground Engineering Sydney July Nick O’Riordan PhD PE CEng Director/Principal Arup

2 2 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

3 3 MIT Sloan Management Review, January 23, 2012 Interviews with 4000 commercial sector managers in 113 countries

4 4 Urbanisation Population of Rome Global variations

5 How much carbon do we emit? Total Per capita [Victoria 1230] [NSW 900]

6 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 % by 2050 Carbon budgeting system – cap emissions over 5 year periods

7 Sustainable and resilient Ground Engineering If not us, then who?

8 New EuroNorms: Sustainability of construction works BS EN :2010 Sustainability assessment of buildings: Part 1: General framework BS EN :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

9 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 CO 2 emission impact) to be made enables construction plant utilisation/efficiency to be evaluated

10 Inventory of Carbon and Energy (ICE) University of Bath, UK energy-ice-2/ jsessionid=DA1E0CED9CAFCE0A36AB78C5 D5A704FE BSRIA: UK Building Services Research and Information Association https://www.bsria.co.uk/news/embodied- energy/

11 CO 2 emission factors (kg/kWh generated in UK) Natural Gas 0.19 Diesel0.25 LPG 0.21 Wind0.00 CO 2 emission intensities (kg/tonne) Granite ballast at quarry gate 1.1 Pulverised fuel ash 2.1 Portland cement (non-renewable power source) GJ = 0.06 to 0.1 tonne CO 2

12 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 , ("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

13 California High Speed Rail: Life Cycle Assessment After Chester & Horvath(2010) PKT=passenger-km travelled Capital Carb

14 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 emissions-paper-was-wrong/

15 California High Speed Rail However Chang & Kendall (2011) show around 8 years payback period Is a CO 2 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, aspx

16 New Motorway project payback Year Do Minimum (tonnes/day) Do Something (tonnes/day)

17 Priority 3 (UK ICE Low Carbon Trajectory) Like CapEx and OpEx but for carbon Apply the concepts of CapCarb and OpCarb CapCarbOpCarb Materials Transport Installation Maintenance Usage Whole Life Carbon +

18 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?

19 Piled slab: 11 km (7 miles) length, Channel Tunnel Rail Link project, very soft soils: Thames Marshes, UK

20 Material Embodied Energy intensity (MJ/kg) for CTRL piled slab v embankment comparison Ballast* and sub-ballast1 Compacted fill0.7 Virgin Steel55 Recycled Steel10 Concrete2 Diesel36 density of concrete 2240kg/m3 density of steel 7840Kg/m3 *Includes 100 km round trip from stockpile, but excludes transport from quarry

21 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

22 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

23 For new-build rail in the UK, ballast is a significant component in terms of EE and CO 2 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?

24 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’

25 Slabtrack: WCML Crewe -Kidsgrove

26 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

27 For new build railways in the UK, ballast is a significant component in terms of EE and CO 2 Structural solutions including slabtrack appear more efficient and ‘sustainable’ than ballasted track After Kaini et al, 2008)

28 Embodied Energy relationships (after Workman & Soga, 2004 and DTI, 2000) UK masonry house = 414 GJ (100m 2 ) 52 storey office, Australia = 2590 TJ (130000m 2) 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 = kWh/tonne Wood = c.3000 kWh/tonne Tyres = 8888 kWh/tonne

29 Retaining walls: basic process & EE intensities

30 Carbon in Retaining Walls – steel verses concrete CO 2 emissions /m run 10m 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 30

31 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

32 Embankments on soft ground: treatment methods DDSM / After O’Riordan & Seaman (1994)

33 Some Embodied Energy intensity values for soft ground engineering ComponentEEI value* Driven 300mm PC pile, 10m long, 2 tonne 6GJ/pile 100 kg/m3 OPC from gas-fired power station energy source, 10m deep, 90 % coverage, 10GJ/ m 2 Vertical, 100mm wide Prefabricated drain, 10m c/c 1.5 MJ/ m 2 Geogrid such as Tensar 0.53 kg/m 2 40 MJ/ m 2 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

34 9m thick embankment, 2m settlement, with vertical 1m c/c Embankment fill MJ/ m2 Vertical drains1.5 MJ/ m2 Geogrid40 MJ/ m2 If the 2m settlement, and the associated time for consolidation can be avoided using BASP piling, the comparable EE becomes Embankment fill9800 MJ/ m2 300mm sq. driven c/c 6000 MJ/ m2 Tensar geogrid 40 MJ/ m2 TOTAL DDSM solution would be a further 5000 MJ/m2 above BASP After O’Riordan (2006)

35 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%.

36 Seven different alternative design concepts Concord Community Reuse Plan Alternative 1 Business-as-usual Alternative 2 Maximum development Alternative 5 Concentrated development

37 SATURN model IMPACT (average speed) CO 2 emissions Established baseline CO 2 for 2008 Established baseline CO 2 for 2008 Calculate future emissions Calculate future emissions Sustainable transport analysis

38 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 Project95,208145,76652,446 Stationary emissions (TCO 2 e) 400,470457,074350,028 Total gross emissions (TCO 2 e)495,678602,840402,474 Service population (residents + jobs)39,20059,60045,800 GHG efficiency rate (TCO 2 e/person) Concord Community Reuse Plan

39

40 24km long; dual 3-lane motorway 2 major interchanges; 29 structures New motorway Carbon comparison Structures incl foundations Pavement Earthworks

41 Effect of vertical profile/alignment

42 Tunnel vs Bridge “Long Tunnel”“Long Bridge” Low gradient: low Op CarbHigh gradient: high Op Carb

43  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

44 Sendai airport, Miyagi prefecture, NE Japan Tsunami from Tohoku earthquake March September June Design for resilience ear.html

45 Repairable Limit State After Honjo (2010)After SEAOC (1995)

46  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 CO 2  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!

47 Smarter analyses: piled foundations in karst

48 Coastal protection assessment, Monterey Bay CA

49 Comparison of probability of failure during design earthquake, and EE of selected solution Soga & Chau (2006) x10

50 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

51 Caltrans and monopiles Carbon footprint of 4m dia. monopile = 20 No 1m dia.CIDH piles

52 Utility evaluation and resilience, urban centers/CBD Transbay Transit Center, San Francisco

53 Electrical – Gas - Water Utility Plan E E W G E Utility evaluation and resilience, urban centers/CBD

54 3.0 s : first mode period of structure

55 Soil-Structure Interaction, Analysis Model Bus Ramp TTC Superstructure TTC Trainbox Tiedowns Soil Domain Ground Motion

56 Wet Utility Flexible Joint

57 Multi-functional, co-located buried infrastructure

58 Natural temperature gradients at shallow depth Pile test site at Monash Uni, Clayton, after Wang et al (2012)

59 Geothermal modelling and feedback systems AnalysisHoop stress (MPa)Tensile Stress (MPa) WinterSummerWinterSummer ‘Normal design’ in LC W extraction W extraction Extracting 30W/m 2 Peak summer temp in tunnel is 36 degrees

60 Geothermal piles Lambeth College thermal pile load test Bourne-Webb et al (2009) Energy pile test at Lambeth College

61 LS-DYNA model 23m Top 6m of pile has diameter 610mm 4m Remainder of pile has diameter 550mm 5m

62 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. 3. Reload to 1.2MN 2. Unload 1. Load to 1.8MN

63 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. 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

64 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

65 Sustainable ground engineering: ability to influence outcome during a project lifetime After Pantelidou et al (2012) Vehicle/structure characteristics Supply chain Define repairable limit state Minimise waste

66 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

67 Sustainable and resilient Ground Engineering If not us, then who? If not now, then when?

68 Thank you

69 An uncertain future is the greatest happiness of the greatest number that is the measure of right and wrong A Fragment on Government, Jeremy Bentham, 1776


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