Development of Strain Based Vibration Controls to Lower Costs of Constructing Transportation Facilities in Dense Urban Locations

Proposed work will begin development of strain and displacement based methods, guidelines, and criteria for the evaluation and protection of structures subjected to close-in blasting for development of urban transit facilities. Currently New York City (NYC) is blasting to construct some half dozen mass transit facilities adjacent to and sometimes within existing facilities .The total cost of these projects exceeds 17 billion dollars. Since all of these projects involve tunnels, shafts and escalator inclines in rock, rock excavation costs are a significant cost factor. This work relates to protection of existing structures from external loads and improving construction efficiency and safety. Primary hazards associated with blasting adjacent, contiguous and within structures include permanent rock mass displacement from delayed gas pressures, ground strains from wave propagation as well as vibratory response. Existing methodology is often applied quite conservatively in the form of permissible ground particle velocity which leads to confusing specifications and increased construction costs. The project will culminate with a report describing best available practice for blasting close-in (adjacent, contiguous or within structures) and procedures for determining blast-induced stress/strain, and guidelines for appropriate instrumentation for blast control. This proposal responds to three of Research and Innovative Technology Administration (RITA) Chief Administrator Appel's 2009 articulation of Department of Transportation (DOT) Secretary La Hood's four goals for United States Department of Transportation (USDOT): accelerate economic recovery, provide a sustainable mobility system, improve quality of life by fostering livable communities, and advance transportation safety. Safety: Every day some 7500 pounds of explosives are detonated in NYC to move these projects forward. Many of these blasts occur within 10's of feet (and less) of operating rail and subway lines carrying millions of passengers each day as well as historic structures of iconic value such as Vanderbilt's Grand Central Station. Three issues involved in close in urban blasting have been exacerbated by conditions in New York City: control of the explosives, design and detonation of the blasts and measurement of the results. Prohibition of explosive storage on Manhattan has increased the complexity of New York City Fire Department (NYFD) oversight. Needless restriction of allowable vibration levels has led to non-explosive removal of rock which increases construction costs. Complex blast site and adjacent (and above) building geometry requires new approaches for appropriate instrumentation to measure blast response. Uniquely valuable data generated by this unprecedented burst of close in blasting activity is in danger of being lost. These data are not being archived or mined for their future engineering value. Synthesis of these data may help lower the costs of transit facilities such as ARC Hudson River Connector Tunnel canceled by New Jersey for fear of its high cost. Infrastructure Technology Institute (ITI) can provide a mechanism to collect and interpret unique data. For instance, the 7.3 billion dollar East Side Access project beneath Park Ave and Grand Central Station has involved extensive strain gage measurement of column response to blasts 16 feet directly below the column footings. These columns, which support glass encased, tall buildings along Park Avenue extend down through the now buried switch yards of the Grand Central Station. They show that the vibration response is much lower than anticipated. There has been no other similar strain gauge study of this magnitude. Yet because of the low response, attention has shifted to other issues and the data are in grave danger of being lost. Ultra high frequency excitation motions generated by blasting contiguous to and inside of buildings require special care in transducer selection, placement and attachment. In addition delayed gas pressures can produce ground motions not normally seen at more typical, larger stand-off distances. NYFD, who monitors both the transport and external effects of explosives, have become concerned that inexperienced design engineers and instrumentation specialists may inappropriately control and measure the results of blasting. ITI can assist NYFD (and other agencies that regulate vibrations that affect the construction and operation of transport such as Metropolitan Transit Authority (MTA) and Port Authority New York New Jersey (PANYNJ ) to develop a forum for the affected parties to discuss the unique issues. This forum would then undertake and sponsor investigations of present techniques as well as alternative means of measuring building response to the close-in blasting . It is envisioned that ultimately this forum could work with other organizations such as the International Society of Explosive Engineers (ISEE) to develop special training and certification for close in blasting. Sustainable mobility systems to improve quality of life; Major transit projects in NYC with significant rock construction are expected to cost over 17 billion dollars. The following descriptions were extracted from an 2008 ENR article. The $7.3 billion East Side Access began in 1999 to increase the number of people Long Island Railroad could bring into Midtown Manhattan. The $2.1 billion Seventh Line extension aims to better serve the Jacob K. Javits Convention Center. The $4.45 billion Second Avenue Subway project will provide a two-track line along Second Avenue from 125th Street to the financial district, which is anticipated to decrease overcrowding and delays on the Lexington Avenue line. Work continues on the Port Authority's $3.2 billion World Trade Center Transportation Hub, which will create a new PATH station and connect to the Fulton Street Transit Center.

    Language

    • English

    Project

    • Status: Completed
    • Funding: $40639.00
    • Contract Numbers:

      60029795

    • Sponsor Organizations:

      Infrastructure Technology Institute

      L260 Technological Institute
      2145 Sheridan Road
      Evanston, IL  United States  60208-3109
    • Principal Investigators:

      Dowding, Charles

    • Start Date: 20110901
    • Expected Completion Date: 0
    • Actual Completion Date: 20130831
    • Source Data: RiP Project 32981

    Subject/Index Terms

    Filing Info

    • Accession Number: 01490688
    • Record Type: Research project
    • Source Agency: Infrastructure Technology Institute
    • Contract Numbers: 60029795
    • Files: UTC, RiP
    • Created Date: Aug 29 2013 1:01AM