Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

Excavation for Boston’s Central Artery project included one of the most interesting temporary excavation support system failures in recent history (1993). The wall moved much more than predicted at a depth of 41 feet, approximately 2/3 of the final 60 foot excavation depth. Jet grouting was used to stabilize the bottom of the excavation before proceeding to the full depth. The excavation support system provided space for a cut and cover section of Interstate I-90’s Third Harbor Tunnel approach to Logan Airport. The permanent structure is a concrete box section of the tunnel. The excavation system consisted of a tied-back soil mix wall (SMW) penetrating a thick zone of over-consolidated Boston Blue Clay. Previous published papers and published discussions explore the possible causes of the failure. This paper investigates some of the key issues and questions raised from this case history as the project remains a fertile topic for reflection, re-examination of the issues related to bottom stability, the common use of the assumption of undrained conditions, selection of appropriate soil parameters and methods for the prediction of movements associated with excavation support systems.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

Tied-Back Wall Failure, Boston, MA

Chicago, Illinois

Excavation for Boston’s Central Artery project included one of the most interesting temporary excavation support system failures in recent history (1993). The wall moved much more than predicted at a depth of 41 feet, approximately 2/3 of the final 60 foot excavation depth. Jet grouting was used to stabilize the bottom of the excavation before proceeding to the full depth. The excavation support system provided space for a cut and cover section of Interstate I-90’s Third Harbor Tunnel approach to Logan Airport. The permanent structure is a concrete box section of the tunnel. The excavation system consisted of a tied-back soil mix wall (SMW) penetrating a thick zone of over-consolidated Boston Blue Clay. Previous published papers and published discussions explore the possible causes of the failure. This paper investigates some of the key issues and questions raised from this case history as the project remains a fertile topic for reflection, re-examination of the issues related to bottom stability, the common use of the assumption of undrained conditions, selection of appropriate soil parameters and methods for the prediction of movements associated with excavation support systems.