Session Start Date

6-1-1988

Abstract

A deep internally braced excavation in soft clay was performed for a pump station at a sewage treatment plant in Milwaukee, Wisconsin. The design was influenced by the limited site area; potential for bearing capacity failure and/or hydrostatic blowout in the bottom of the excavation; and the necessity to limit ground deformation outside the excavation to protect existing structures and utilities. A performance specification and design was prepared by the owner's engineer. The design included minimum earth and hydrostatic lateral loading conditions to be used by the contractor, a minimum depth of penetration for the earth support system, and a maximum allowable horizontal deflection. The final earth support system design was prepared by the contractor and reviewed by the owner's engineer. Construction monitoring included slope inclinometers (to measure horizontal deflection of the earth support system) and piezometers to measure hydrostatic pressure in a confined aquifer. Measured horizontal deformation of the excavation support system exceeded the predicted deformations. The influence of the contractor's methods and sequence of excavation and earth support system installation on the actual-versus-predicted deformations are also discussed.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Second Conference

Publisher

University of Missouri--Rolla

Publication Date

6-1-1988

Document Version

Final Version

Rights

© 1988 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Design, Construction and Performance of a Deep Excavation in Soft Clay

A deep internally braced excavation in soft clay was performed for a pump station at a sewage treatment plant in Milwaukee, Wisconsin. The design was influenced by the limited site area; potential for bearing capacity failure and/or hydrostatic blowout in the bottom of the excavation; and the necessity to limit ground deformation outside the excavation to protect existing structures and utilities. A performance specification and design was prepared by the owner's engineer. The design included minimum earth and hydrostatic lateral loading conditions to be used by the contractor, a minimum depth of penetration for the earth support system, and a maximum allowable horizontal deflection. The final earth support system design was prepared by the contractor and reviewed by the owner's engineer. Construction monitoring included slope inclinometers (to measure horizontal deflection of the earth support system) and piezometers to measure hydrostatic pressure in a confined aquifer. Measured horizontal deformation of the excavation support system exceeded the predicted deformations. The influence of the contractor's methods and sequence of excavation and earth support system installation on the actual-versus-predicted deformations are also discussed.