Session Start Date

5-6-1984

Abstract

The geotechnical considerations affecting the design and construction of an immersed-tube tunnel are presented. Construction of the tunnel required deep excavations in overconsolidated fissured and slickensided clay deposits. Undrained, long-term residual and fully softened drained strength parameters were determined. The depth of excavation and the life of the cut slope were considered in selecting the design parameters for the slope study analysis. A tied-back soldier pile and lagging system was used for protection of the east end excavation in a congested urban area. Each tie-back was tested according to a simple acceptance criteria developed during construction. Lateral displacements measured behind the excavations were negligible. Hydraulic dredging of the trench was accomplished with the aid of cutterheads. Dredge spoil was pumped into a contained offshore disposal facility. Flocculants were added to the dredge slurry to accelerate settling of the solids before the effluent was discharged into the Harbor. Construction of the immersed-tube tunnel was completed on schedule.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

First Conference

Publisher

University of Missouri--Rolla

Publication Date

5-6-1984

Document Version

Final Version

Rights

© 1984 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 6th, 12:00 AM

Geotechnical Aspects of the Fort McHenry Tunnel - Design and Construction

The geotechnical considerations affecting the design and construction of an immersed-tube tunnel are presented. Construction of the tunnel required deep excavations in overconsolidated fissured and slickensided clay deposits. Undrained, long-term residual and fully softened drained strength parameters were determined. The depth of excavation and the life of the cut slope were considered in selecting the design parameters for the slope study analysis. A tied-back soldier pile and lagging system was used for protection of the east end excavation in a congested urban area. Each tie-back was tested according to a simple acceptance criteria developed during construction. Lateral displacements measured behind the excavations were negligible. Hydraulic dredging of the trench was accomplished with the aid of cutterheads. Dredge spoil was pumped into a contained offshore disposal facility. Flocculants were added to the dredge slurry to accelerate settling of the solids before the effluent was discharged into the Harbor. Construction of the immersed-tube tunnel was completed on schedule.