Service Life Assessment and Predictive Modeling for an Aging Critical Infrastructure Proceedings of a Workshop (2021) / Chapter Skim
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4 Waterways Infrastructure
4 Waterways Infrastructure
Pages 20-33
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From page 20... ...
He emphasized that the Corps is different from many other federal agencies in that it does not receive money for people or for supplies; it instead receives funding for projects. Belk introduced the "giant math problem" confronting the infrastructure investment in the Corps: based on an estimate from the World Economic Council, approximately $7 trillion is expected to be needed for infrastructure between 2016 and 2030 to sustain current levels of economic activity and quality of life.
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Focus on investments that will achieve an outcome over time. Belk then described the Corps' strategy for maintenance management, which includes the following phases: critical asset visibility, noncritical asset visibility, and required minimum maintenance data.
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FIGURE 4.2 U.S. Army Corps of Engineers life cycle asset management.
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However, the advantages of the public-private partnership, he continued, include the abil ity to extend service life and sustain performance of existing assets as well as to accelerate delivery and accrual of project benefits to new infrastructure. While the federal government carefully considers the use of money from the private sector to deliver public works (instead of the use of federal government funds with nearly
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McKenna explained that an aerial satellite image of a structure captures only the appearance of that structure, as opposed to its behavior, during one particular
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McKenna shared an anecdote of troops in Iraq who tried to cross a bridge based upon its stable appearance in a satellite image taken just 1 hour previously; yet when they arrived, the bridge was not there, and so the operation was com promised. The Remote Assessment of Critical Infrastructure program begins to address this problem with "persistent standoff assessment and monitoring for the purpose of stability analysis, load ratings, structural health monitoring, and failure phenomenon analysis in both military and civil works applications utilizing infrasound," according to McKenna.
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McKenna explained that construction practices for an area are associated with expected modal behavior for a bridge in good condition in that same area. She added that engineering tools (such as assigning military load classification remotely)
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that needs to be addressed, including varied materials and operational facilities over 200 years old. His team focuses on trying to understand the current state of distress in existing structures, predict how that distress in going to progress, and then use that knowledge to make informed decisions in a limited funding environment -- so that investments will help maintain operability in high-impact infrastructure.
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From page 28... ...
These data are translated to a different time scale, ultimately leading to a better understanding of future damage, which is a powerful planning tool for engineers. Moser noted that combining service life models with a life cycle cost analysis can be a useful tool to consider repair and rehabilitation alternatives (see Fig ure 4.3)
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From page 29... ...
The city was completely flooded, mostly owing to failures in the levee and flood wall system. The Interagency Performance Evaluation Taskforce, comprising 350 members from 50 federal agencies, state organizations, and academic institutions, was asked to "provide credible and objective scientific and engineering answers to fundamental questions about the performance of the hurricane protection and flood damage reduction system in the New Orleans metropolitan area," accord ing to Mosher:
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From page 30... ...
With this system-wide strategy, the task force tried to understand the breach mechanics and the nonbreach analytical analogs and then extend them across the whole area to assess system-wide integrity. The performance evaluation included field observations, field and laboratory investigations, historical information, slope stability, nonlinear finite element analysis, centrifuge physical modeling, and peer review.
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Although there were similar failures on numerous canals, there were different reasons for each failure. The task force's analysis demonstrated that the 17th Street Canal breach mechanism included the following: deflection of the I-wall by surge/waves; full hydrostatic pressure along the wall that split the levee into two blocks; weaker clay at the levee toe that caused failure in the subsurface clay layer; and displacement of the soil block from the wall back.
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From page 32... ...
The task force also learned about the need to assess the erodibility of the emplace levee materials, to avoid silts and sands and hydraulic fills for levee construction, and to increase the compaction effort for levee materials, according to Mosher. Discussion De la Garza asked Peter Matthews if a readiness alarm sounded in STRANSCOM when three strategic seaports and two alternative seaports were U affected during Hurricane Katrina.
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Mosher noted improvements including paved levees, berms to increase strength, increased wall heights, and relocation of pump ing stations. Michael McGrath, McGrath Analytics, LLC, asked Mosher about the role of forecasts for changes in sea level.
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