Underground Engineering for Sustainable Urban Development (2013) / Chapter Skim
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6 Innovative Underground Technology and Engineering for Sustainable Development
6 Innovative Underground Technology and Engineering for Sustainable Development
Pages 145-186
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From page 145... ...
High lighted are technologies that provide opportunities for significant improvement in the delivery of cost-effective lifecycle performance for underground facilities, contribute to improvements in underground space usage, and contribute to resil ient and sustainable urban solutions. 145 Underground Engineering Camera-Ready.indd 145 2/6/2013 3:16:58 PM
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Advances in materials technology, computer science, robotic construction technology, and laser guidance have allowed improved subsurface excavation using modern slurry shield and earth pressure balance boring machines1 (Figure 6.2) and rock tunnel boring machines (Figure 6.3)
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FIGURE 6.2 Cross-section of earth pressure balance tunnel boring machine. This tunnel ing technology is ideal for homogenous soft soils.
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Similarly, today's engineering and technology developments will be crucial to an economi cally constructed, functional, attractive, energy efficient, and sustainable urban environment. This chapter is grouped under the following themes: • technologies for underground site characterization, including geologic setting, rock and soil properties, and existing underground infrastructure; • technologies for design and analysis for underground technologies; • technologies for construction of underground space; • technologies for effective asset management; and • technologies that promote sustainability and resilience.
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Suggested are technologies for analyses that allow improved application of the observational method. TECHNOLOGIES FOR UNDERGROUND SITE CHARACTERIZATION Engineering urban underground space requires detailed knowledge of the underlying geology and the geologic and human-development histories of a site, alignment, and adjacent areas that may affect or be affected by proposed develop ment.
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, but existing assessment tools cannot provide complete spatial coverage, accurate zonation, and in-situ material properties. At a project scale, hazardous materials encountered during underground construction can add large and unexpected costs to a project and delay project delivery.
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For example, society is grappling with the risks associated with the emerging technology of carbon dioxide sequestration. As more large scale sequestrations are planned, the need to examine their potential impacts on the ability to develop underground space becomes even greater, because, for example, carbon dioxide could seep into underground space.
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Research into the fusion of multi-sensor data that would allow noninvasive technologies to accom modate a wider range of ground conditions and to improve their ability to resolve ground properties and the presence and location of buried objects is under way both in the United States and overseas. Similarly, research by the military into the detection of land mines and deep covert tunnels can have significant benefits in broader civil engineering applications.
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Unmapped or inaccurately mapped underground infrastructure poses poten tial hazards and risks for underground construction workers, the construction site, other infrastructure, and other people in the vicinity. Encountering unexpected infrastructure may necessitate revised construction planning or repairs.
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Such comprehensive FIGURE 1 Example of three-dimensional engineering geological modeling employed by the British Geological Survey for visualizing variability in geologic materials and their physical properties. SOURCE: Reeves, 2010.
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To move toward engineering practices that are consistent with such sustain ability goals, data related to underground infrastructure development need to be archived in formats and with tools that make them retrievable and accessible for the infrastructure life cycle -- and beyond (to account for infrastructure artifacts in place well after closure or decommissioning)
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From page 156... ...
Sociopolitical and economic issues, discussed in earlier chapters, influence infra structure design, perhaps at the expense of sustainability. Design and analysis of underground infrastructure is often heavily focused on the immediate open ing and support of underground space; long-term issues related to sustainable maintenance and use are often overlooked, as are lifecycle contributions of the infrastructure to society.
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From page 157... ...
Constraints created by the limitation of design tools, or by the limitations of those who use the tools, also limit the ability to design underground infrastructure optimally and to reduce lifecycle costs. Underground infrastructure design can benefit from iterative analyses of designs -- especially innovative designs -- in a virtual environment.
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Experience The lack of education and training that allows good engineering of under ground systems is of growing concern in the United States and will ultimately affect the resilience of underground infrastructure and sustainability of the urban development. Fewer than five U.S.
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, and the propagation of fire and smoke in occupied underground spaces. All computational methods, whether based on discretization (e.g., differential versus integral)
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Box 6.2 describes some of the needs related to analytical and computational model development. TECHNOLOGIES FOR UNDERGROUND CONSTRUCTION Technological developments related to excavation, ground modification, improvement, support, tunnel boring, and use of excavated materials are impor tant for developing underground space more efficiently, cost effectively, and Underground Engineering Camera-Ready.indd 160 2/6/2013 3:17:05 PM
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, and by the need to remain competitive in an international market for underground construction contracts. The importance of underground infrastructure development that contributes to sustainable development is now being recognized (e.g., ECTP, 2005)
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Major cut-and-cover projects in urban areas provide opportunities to update other underground facilities in their vicinity. For example, utilidors may be incor porated in transportation projects, and underground pedestrian networks in city center redevelopments (as occurred in both Montreal and Toronto)
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As cities become more densely developed and use more underground space, blasting approaches that are proven to minimize damage and nuisance will be desired. Tunnel Boring Machine Technologies for Rock Excavation Early variations of TBMs for soft rock were developed in the late 1800s (e.g., the Beaumont English boring machine was used on one of the early attempts to create the Channel Tunnel between England and France; Maidl et al., 2008)
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. Improving control of deformation due to tunneling in soil is a key to limiting damage to existing infrastructure and improving capacity to sustainably develop underground space in most urban areas.
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Other beneficial advances could include enhancing techniques to decrease overcut during mining, improving directional control during mining to decrease the allowances for align ment errors, and developing more efficient and rapidly deployed formwork for cast-in-place linings. Tunnel Boring Machines in Soil Recent technological developments for tunneling in soil include the earth pressure balanced TBM (see Figure 6.2)
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. Research is needed in these areas to improve SEM application and contribution to more sustainable underground space development.
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to address long-term planning and the ability to choose the most sustainable and best uses of urban underground space. Ground Improvement Technologies It is often necessary or productive to temporarily or permanently change soil or groundwater properties during underground construction to ease facility design, construction, or operation.
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Monitoring the behavior of the underground facility and surroundings during construction helps to ensure safety, assess performance, validate design, and inform necessary design changes. Figure 6.8, for example, shows the level of detail possible using laser scanning to monitor excavation progress.
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helps to protect groundwater resources and air quality above and below the sur face. Contractors typically monitor and analyze construction processes and opera tions (e.g., shift utilization, equipment downtime, repair or replacement, ground support installation, muck volumes, and grout takes)
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TECHNOLOGIES FOR EFFECTIVE ASSET MANAGEMENT The ability to operate and maintain underground infrastructure over the long term is essential to its sustainability and to that of the larger system to which it belongs. All built systems require and need to accommodate maintenance, Underground Engineering Camera-Ready.indd 170 2/6/2013 3:17:10 PM
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Many forms of underground infrastructure are difficult or costly to inspect. Most underground piping, for example, does not allow person entry for direct inspection, and taking pressure pipes (e.g., for gas, oil, or water)
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. The sensors measure the response of the soils and infrastructure to construction activities.
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Automated total stations, shown in green are used as wireless nodes for dedicated project wireless network. Designed and implemented by Arup North America Ltd.
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, and rapid technological developments in the wireless sensor field can render existing sen sors nearly obsolete in less than a decade. Significant developments are needed in this area to fully achieve the vision of smart underground structures.
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Applied research needs include the continued improvement of inspection, assessment, rehabilitation, and replacement technologies -- including ways to upgrade occu pied underground facilities to meet current expectations of health, safety, and comfort. Better design and planning options for the reuse of existing urban infra structure and creating multi-use options for the future (e.g., new design concepts for facilities that are easier to rehabilitate or retrofit for enhanced service life or repurposing)
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data) can provide locations of system elements needing repair, relay real-time information regarding conditions in underground space, and map locations of automated sensing and maintenance devices, but GPS and cellular signals are difficult to receive underground.
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Meth ods and automated systems to interpret these data and report problems to an operator would enhance optimal operation and maintenance of underground systems. Enhanced data management technologies can aid understanding of the performance of underground infrastructure as part of the larger urban system and allow planners to anticipate interdependencies and interferences that affect func tionality and quality of service.
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Because sensor data inform decisions affecting, for example, life safety (e.g., traffic operations, ventilation) , the well-being of underground infrastructure occupants depends on the secure and proper function ing of the system.
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Maximizing the ability of the ground to be part of the support system, or reusing excavated materials from within or near a project, would help to increase efficiency in material use or reuse. New lining and underground construction technologies are needed that reduce material use and improve long-term facility performance.
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Underground space use requires significant quantities of energy for ventila tion, temperature control, lighting, fire detection, and other systems throughout the life of underground facilities. Some advances allow greater efficiency, but higher installation costs could deter their adoption.
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Investigation of thermal effects and long-term impacts on both underground climate and underground space usage is warranted. The use of lower temperature geothermal resources can help to reduce net emissions of greenhouse gases through the use of ground source heat pumps or similar heat exchange systems for heating or cooling structures and potable and nonpotable water for residential use.
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1986. Tunnelling and Underground Space Tech nology.
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Tunnelling and Underground Space Technology.
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2010. Attributed 3D Geologic Models in the UK and Their Application to Planning and the Sustainable Development of Underground Space.
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. Available: http://pubs.usgs.gov/ fs/2008/3082/pdf/fs2008-3082.pdf (accessed July 6, 2012)
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