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Ray Sterling, Ph.D., P.E.Professor Emer i tus , Lou is iana Tech Univers i tyTan Swan Beng Endowe d Professor, Nanyang Technolog ica l Univers i ty
Sustainability and Resiliency Issues for Urban Underground Space
Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University2Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Introduction
� Underground space uses include a wide variety of systems critical to societal functioning and urban livability
� Effective underground space use also is a form of land creation
� It is important to assess the sustainability and resiliency implications of an expanded use of underground space
3Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Why Use Underground Space?
� Three main categories of rationale� Location: We want to build a facility in a particular place but
we don’t want to or cannot build it on the surface
� Isolation: We can use the physical attributes of the ground to hide or improve the isolation of certain types of facilities
� Topography and crossings: We can use the freedom from topographic constraints and the ability to tunnel under barriers such as rivers and mountains.
4Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Why is Underground Space Use Important for Singapore?
� Singapore has an increasing population and growing economy but a very limited land area
� At the same time, Singapore is working hard to improve “quality of life” and environmental conditions
� Underground space use is one of the few options that offers significant growth potential for industrial purposes and infrastructure provision with minimal environmental impact.
5Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Making Sensible Choices
� Underground space usually not the first choice for a facility “all other things being equal”
� Underground space use is not a “goal”
� It is often a response to alternatives that have a worse impact on quality of life
� It may eventually be one of only a few viable solutions for continued development
� To make proper choices both land value and environmental protection must be properly included in facility and infrastructure decisions
6Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Build High Rise Structures
� Provides high density with access to daylight
� Intensifies need for infrastructure
� Much of this infrastructure must be provided underground
� Can be out of scale with historic areas
7Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Land Reclamation
� Needs large quantities of fill material
� Extent limited by international treaties and deeper water
� Underground construction can contribute to the fill required
8Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Floating Structures
� Need sheltered offshore location
� In many locations may interfere with recreational use of coastline
� Again, underground construction can help contribute to needed fill for protective reefs, etc.
9Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Underwater Space
� Not too shallow, not too deep
� Need protection from anchors, sinking objects, etc.
� Corrosion issues
� Repair / renewal issues
10Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Offshore Structural Development
� Create underwater space and new “land” using structures rather than fill
� Essentially create underwater space and new land at the same time
� Water easily moved aside
11Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Infill Development / Create a New Ground Level
� Fill between and/or cover over existing land uses
� Create new ground surface
� Need large development or redevelopment
� Create “underground space” aboveground
12Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Sustainability
13Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Pillars of Sustainability
14Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
� Over what time scale is sustainability to be considered? Any consumption of non-renewable resources will eventually lead to exhaustion of those supplies at feasible costs.
� How can the current world population growth be reconciled with global sustainability?
Serious and Difficult Questions (1)
15Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
� How can regional imbalances in needs and resource availability be solved?
� Is it feasible to support current living patterns if regions become critically short of resources or if environmental changes increase the magnitude and frequency of natural hazards?
� Will people need to move to safer or more resource rich areas? Will this be feasible politically?
� The rapid urbanization of the world’s population requires that urban communities must provide a viable mode of living for the foreseeable future.
Serious and Difficult Questions (2)
16Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Past Societal Collapses
� Extent and reversibility of environmental damage - fragility/resiliency of the local environment)
� Climate variations (drought, volcanic eruptions, etc.) and their impact on food supplies, etc.
� Presence of hostile neighbors� Decreased support from friendly
neighbors that interrupts essential trading � Whether and/or how a society recognizes
and responds to the developing crisis.
Issue Advantages or mitigations Disadvantages or limitations
Compactness
� New facilities/services with low surface impact
� Land use efficiency and promotes compactness while maintaining livability
� 3-dimensional planning freedom
� Local geology must be accommodated
� Poor knowledge of geology and existing underground structures
� Irreversibility considerations� Support, span and access
limitations
Isolation
� Protects from climate, storms, fire, earthquake
� Protects from noise, vibration, explosion, fallout, industrial accident
� Provides high security
� Flood protection required� Psychological concerns� Fire safety and personal safety
concerns
Preservation
� Low visual impact� Preserves natural landscape, ecology � Isolates hazardous materials and
processes� Low material degradation
� Skilful design required for best effect
� Environmental degradation from underground construction and use itself
Life cycle cost
� Land cost savings� Potential sale of excavated materials � Savings in specialized features� Savings in maintenance, insurance
and energy use for some facilities� High longevity of facilities
� Often high initial construction cost� Higher degree of cost uncertainty � Often high embodied energy � Limited access may affect operating
cost 18Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Surface Ecology Impact
19Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Renewable vs Non-renewable Attributes
After Bobylev 2009
20Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
� Saving natural resources, including land, water, and biodiversity
� Reducing air pollution (mainly in the transport sector) and unnecessary visual intrusion
� Creating opportunities for less energy use and waste generation (compact city)
� Creating structures less impacted by earthquakes and many other catastrophic events and resilient utility and transportation networks
� Enhancing of overall landscape and environmental quality
� Underground infrastructure allows a reduction of land area covered by manmade structures.
� Compact areas that maintain high living standards can impact energy consumption and climate change
Underground Contributions to Sustainability
21Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
� Deep foundation choices for buildings
� Use of horizontal tiebacks for temporary/permanent support of foundation walls
� Choice of tunnel geometry and construction method
� Use of geothermal heat exchange systems
� Utility layout decisions / HDD impacts / utilidors
� Impact of underground structures on the geoenvironment
Examples of Design Choices Affecting Sustainability
22Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Impact of Foundation Type on Underground Space Use
23Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Sustainable Utility Provision
Wall Street 1917
24Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Key Impacts for Singapore Sustainability
� Major increase in industrial/commercial spaces possible
� Multiple layers possible� Basement spaces
� Rock cavern spaces with multiple internal floors
� Multiple layers of rock cavern spaces possible
� Retains surface environment
� Provides aggregate and fill to support other construction and space creation activities
� Allows unobtrusive provision of key infrastructure services
25Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Resiliency
26Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Increasing Complexity of Infrastructure Relationships
� Aging physical systems
� Larger interconnected networks
� Poorly understood interdependencies
� Loss of redundancy for “economy”
After Rinaldi et al. 2001
Interdependencies for 6 Sectors of infrastructure
27Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Metrics for Resiliency
� Describes the extent of loss of performance during the recovery period
Performance response function
Nelson and Sterling 2012
28Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Electric Power Performance for Hurricane Katrina (Entergy New Orleans data)
29Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Interdependence of Social Networks, Mobility and Utilities
� Restoring physical networks only is not enough
30Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Challenges for Broad Application of Resilience
� Engineers and social scientists are not thinking in concert about representation of resilience
� Planners and land use professionals are noticeably absent from discussions of resilience
� Poor linkage between currently defined outcomes/metrics and standards or policy incentives
� The assessment of resilience is not yet standardized, and approaches and models have not been validated
31Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Effects of Decision-making on Resilience
After McDaniels, Chang et al, forthcoming in Global Environmental Change
Response time
Excesscapacity, robustness
Support for function and delivers from outside the system
Influence of Adaptive Response Mgmt
Influence of Mgmt before an event
Event magnitude w/r to system capacity
Specific Resiliency Issues for Underground Space Use
32
Hurricane Sandy, New York Oct. 2012
Type of Event Advantages or mitigations Disadvantages or limitations
Earthquake
Ground motions reduce rapidly below surface
Fault displacements must be accommodated
Structures move with the soil Instability in weak materials or poor configurations
Hurricane, Tornado Wind loadings have minimal impact on fully buried structures
Damage to shallow utilities from toppling of surface structures such as trees and power lines
Flood, Tsunami Ground provides protection from surge and debris flow
Extensive restoration time and cost if the structure is flooded
External fire, blast Ground provides effective protection
Entrances and exposed surfaces are weaknesses
External radiation, chemical/biological exposure
Ground provides additional protection
Appropriate ventilation system protections required
Internal fire, blast Limited extent of damage with appropriate compartmentalization
Confined space increases internal damage and personnel risk
Internal radiation, chemical/biological releases
Limited extent of damage with appropriate compartmentalization
Confined space increases internal damage and personnel risk 34Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Protection, Security and Resiliency
� Seismic amplitudes reduce rapidly below surface
� Structures well protected from external events
34
Earthquake Date Magnitude Impact on Subway
Mexico City 1985 8.1 No damage to tunnels. Some power disruption. Patrons evacuated safely
Loma Prieta (SF) 1989 6.9 No damage to tunnels. Subway served as lifeline structure.
Northridge 1994 6.7 No damage
Kobe, Japan 1995 7.2 No damage to tunnels, damage to station and sewer pipes. Attributed to 1962 design with moderate seismic provision
Taipei 2002 6.8 No damage
Chile 2010 8.8 Running next day. Some damage at entrance to station
(From ITA WG20 Report)
35Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Flooding a Key Concern for Underground Structures
� Protection of entrances against flooding is a key
� Underground structures well protected against forces generated by tsunamis, floods and debris flow
Flooded Taoranting Subway Station in Beijing, June 23, 2011. [Photo/Xinhua]
36Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
From Dr. Tetsuya Hanamura
2011 Earthquake / Tsunami Effect on Infrastructure in Sendai
� Only minor damage in below ground portions of subway and rail network
� Most aboveground gas facilities near seaside were destroyed
� Underground LNG tanks safe� Low damage in higher pressure
gas pipelines, more in low pressure lines
� Aboveground power plants destroyed
� Underground electric transmission lines only damaged at 14 locations
� Minor damage in water piping network
37Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
External Fire / Blast
� Types of Risk� Bush fires
� Industrial explosions
� Terrorist actions
� Nuclear explosion
� Mitigation� Protection of openings
� Keep out burning debris
� Withstand flying projectiles
� Deflection of blast outside the structure
� Blast resistant openings
38Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
External Radiation, Chemical/Biological Exposure
� Enclosed space beneficial
� Provide ventilation with filtration and, if necessary, blast protection
Filtration
Blast valves
39Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Internal Fires Underground
40Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Major Tunnel Fires
41Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Elements of Fire Safety in Tunnels and Underground Spaces
� Control of hazardous material and cargos
� Fire Detection
� Ventilation
� Communication Systems / Traffic Control
� Sprinklers/Stand Pipes (Hydrants)/Water Supply / Portable Fire Extinguishers
� Tunnel Drainage
� Egress / areas of refuge
� Emergency Response
42Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Internal Chemical / Biological Releases
� Enclosed space not beneficial for those inside
� Mitigation� Prevention
� Ventilation
� Egress
� CompartmentalizationExample: In five coordinated attacks, sarin was released on several lines of the Tokyo Metrokilling thirteen people, severely injuring fifty and causing temporary vision problems for nearly a thousand others.
43Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Assessment of Damage to Urban Buried Infrastructure in the Aftermath of Hurricanes Katrina and Rita
44Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Overview
� Katrina made landfall on August 29, 2005. Hurricane left relatively little damage but levee failure caused catastrophic damage
� EPA preliminary estimates to repair decimated water and sewer systems: $3 - $10 billion.
� Natural gas distribution system, power and telecommunication – an additional $1-2 billion.
� Costs of restoring municipal services alone dwarf costs of rebuilding lower Manhattan following 9/11.
45Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Damage to Buried Infrastructure – Shallow Buried Infrastructure Systems
� Falling trees / tree root system � Common failure mode in mature neighborhoods � Damage to shallow utilities:
� Water� Low pressure gas� Power� Telecommunication
� Clean-up activities� Debris clearing operations � Off-road heavy equipment � Damage to hydrants
� Emergency response issues� Personnel could not report for duty� Landmarks obliterated� Electrical systems for pumps flooded
46Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Damage to Buried Infrastructure – Severing of House Connections to Buried Utilities
� Shifting of above ground structures
� Even if structure experiences only partial buoyancy – rigid connections are severely damaged
47Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Damage to Pipe Networks
� Potable water� Drop of pressure in pipes coupled with 3 m of external hydrostatic pressure can
result in the infiltration of contaminated water to the water distribution system
� Potential damage to liner rehabilitation systems
� Sanitary and Storm Sewer Lines� Differential settlement � Loss of bedding support � Off-road heavy equipment
� Natural gas� Salt water contamination / corrosion
of valves and meters� Acceleration corrosion of pipes� Mostly low pressure network affected
48Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Short-term vs Long-term Impacts
� Short-term� Loss of potable water supply / water-borne illness
potential� Exfiltration of wastewater from damaged system /
pollution� Down time / business losses / population loss � Costly temporary services
� Long-term� Accelerated deterioration of buried pipes and
manholes� Infiltration causes loss of pipe and road bedding� Collapse of road surfaces� Infiltration can overwhelm wastewater plants in
wet weather � Increased failure of water mains
49Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
2012 Hurricane Sandy Impacts on New York
� Many similar issues as for Hurricane Katrina� Various metro and road tunnels flooded
� Storm surge� Heavy rainfall� Old metro system with many openings to surface
� Trees and overhead power lines downed� Electrical substations flooded� Power to lower Manhattan restored in about 4 days� 80% of metro service restored in about 5 days� Long-term repairs needed in many areas
50Tan Swan Beng Lecture, July 9, 2013, Nanyang Technological University
Summary and Conclusions
� Underground space use can be a strong contributor to a livable and sustainable future for Singapore
� Underground space use offers a number of advantages in terms of urban resiliency but key issues such as flooding potential and fire/life safety must be considered carefully
� The potential large increase in the use of underground facilities for various purposes provides a significant incentive for advanced research� Better understand planning and societal implications� Improve technologies to lower costs and improve functionality� Provide greater synergy among various development alternatives for
maintaining a spacious and livable Singapore
MANY THANKS TO THE TAN SWAN BENGFOUNDATION SUPPORT FOR THE
OPPORTUNITY TO VISIT NTU AND COLLABORATE IN ADDRESSING THESE
IMPORTANT QUESTIONS
Questions and Discussion