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Sustainable and Resilient Ground Engineering

Sustainable and Resilient Ground Engineering. Nick O’Riordan PhD PE CEng Director/Principal Arup nick.oriordan@arup.com. Sydney July 25 2012 . Sustainable and resilient Ground Engineering. Context Embodied energy Capital carbon investment and operations & maintenance carbon

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Sustainable and Resilient Ground Engineering

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  1. Sustainable and Resilient Ground Engineering Nick O’Riordan PhD PE CEng Director/Principal Arup nick.oriordan@arup.com SydneyJuly 252012

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

  4. Urbanisation Global variations Population of Rome

  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 2020 • 80% 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 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

  9. 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 Embodied Energy (EE)

  10. 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 https://www.bsria.co.uk/news/embodied-energy/ BSRIA: UK Building Services Research and Information Association

  11. Natural Gas 0.19 Diesel 0.25 LPG 0.21 Wind 0.00 CO2 emission factors (kg/kWh generated in UK) • 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

  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-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

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

  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 http://www.cahsrblog.com/2010/12/hsr-emissions-paper-was-wrong/ ....the damage is done

  15. 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-rail-041712.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!

  16. New Motorway project payback

  17. Like CapEx and OpEx but for carbon Priority 3 (UK ICE Low Carbon Trajectory) Apply the concepts of CapCarb and OpCarb Materials Maintenance + Transport CapCarb OpCarb Installation 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. 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 Material Embodied Energy intensity (MJ/kg)for CTRL piled slab v embankment comparison *Includes 100 km round trip from stockpile, but excludes transport from quarry

  21. 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 310 piled slab - Assumption and boundaries (after Chau et al, 2012)

  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 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?

  24. ‘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’ Slab track v ballasted track:Is received wisdom from the Shinkansen (the bullet train) truly correct?

  25. Slabtrack: WCML Crewe -Kidsgrove

  26. EE comparison for ballasted v slabtrack • EE ballasted track maintenance=0.8 TJ/km • Total EE ofunoptimisedslabtrack = 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 CO2 Structural solutions including slabtrack appear more efficient and ‘sustainable’ than ballasted track After Kaini et al, 2008)

  28. 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 Embodied Energy relationships (after Workman & Soga, 2004 and DTI, 2000)

  29. Retaining walls: basic process & EE intensities

  30. Carbon in Retaining Walls – steel verses concrete CO2 emissions /m run 10m basement wall (recycled steel) Cantilever diaphragm 1500mm Propped diaphragm 1000mm Propped diaphragm 800mm Concrete basement wall 400mm Sheet piles extracted Propped sheet pile AZ34 Rented Props and sheet piles AZ34 Sheet pile reuse

  31. Very soft clays: design parameters difficult to determine without trials Greater certainty by modifying soil behaviour/ load pathways and load magnitude Embankments on soft clay:Speed v certainty

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

  33. Some Embodied Energy intensity values for soft ground engineering * Excludes EE associated with transport of component to site

  34. Embankment fill 12600 MJ/ m2 Vertical drains 1.5 MJ/ m2 Geogrid40 MJ/ m2 9m thick embankment, 2m settlement, with vertical drains @ 1m c/c 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 Tensargeogrid40 MJ/ m2 TOTAL 15840 DDSM solution would be a further 5000 MJ/m2 above BASP After O’Riordan (2006)

  35. 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%. Embodied energy, CO2 footprinting and construction on soft ground

  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 CO2 emissions IMPACT (average speed) Sustainable transport analysis • Established baseline CO2 for 2008 • Calculate future emissions

  38. Concord Community Reuse Plan • Mobile source emissions added to stationary source emissions and normalized across the service population

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

  40. Effect of vertical profile/alignment

  41. Tunnel vs Bridge “Long Tunnel” “Long Bridge” Low gradient: low Op Carb High gradient: high Op Carb

  42. 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.

  43. 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-since-ear.html

  44. Repairable Limit State After SEAOC (1995) After Honjo (2010)

  45. 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!

  46. Smarter analyses: piled foundations in karst

  47. Coastal protection assessment, Monterey Bay CA

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

  49. 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

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