Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Abstract

The jacking of the largest concrete tunnels ever built in the United States required the construction of jacking pits of unusual dimensions and requirements. The location of the pits posed the additional challenge of difficult ground conditions, since the bottom of the pits was in the Boston blue clay. The pits had to have an unsupported span of over 40 feet to accommodate the dimensions of the tunnel, have a solid base to carry the weight of the sections being built and provide lateral resistance to the thrust of the jacks. Treviicos met those challenges by constructing a four feet thick, post-tensioned slurry walls capable of spanning 55 feet without intermediate support and by creating a thirty feet thick jet grouted mass below the sub-grade which had the double function of contrasting the wall at its toe as well as providing a more competent foundation for the jacking operation.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 13th, 12:00 AM Apr 17th, 12:00 AM

Jacking Pits in Boston’s Central Artery Project

New York, New York

The jacking of the largest concrete tunnels ever built in the United States required the construction of jacking pits of unusual dimensions and requirements. The location of the pits posed the additional challenge of difficult ground conditions, since the bottom of the pits was in the Boston blue clay. The pits had to have an unsupported span of over 40 feet to accommodate the dimensions of the tunnel, have a solid base to carry the weight of the sections being built and provide lateral resistance to the thrust of the jacks. Treviicos met those challenges by constructing a four feet thick, post-tensioned slurry walls capable of spanning 55 feet without intermediate support and by creating a thirty feet thick jet grouted mass below the sub-grade which had the double function of contrasting the wall at its toe as well as providing a more competent foundation for the jacking operation.