Location

Arlington, Virginia

Session Start Date

8-11-2008

Session End Date

8-16-2008

Abstract

The two underground stations and portals of Metro Gold Line's East Los Angeles extension were excavated in heavily over-consolidated alluvium. The excavations were supported with heavy soldier piles with pre-loaded steel-pipe struts. When measured strut loads increased to up to 3 times the design value, and strut-waler connections began to buckle, the contractor was directed to install additional struts. Maintaining that the problem had been caused by inadequate construction means and methods, the owner denied a change-order request for this work. This paper describes the contractor’s investigation into the cause of strut overloading in preparation for a formal hearing by a Dispute Resolution Board. The study concluded that the extremely high bracing loads were caused by high in-situ stresses in the region, which had not been accounted for in the shoring-pressure diagrams provided in the contract drawings.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Sixth Conference

Publisher

Missouri University of Science and Technology

Publication Date

8-11-2008

Document Version

Final Version

Rights

© 2008 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

Share

 
COinS
 
Aug 11th, 12:00 AM Aug 16th, 12:00 AM

Effect of High In-Situ Stress on Braced Excavations

Arlington, Virginia

The two underground stations and portals of Metro Gold Line's East Los Angeles extension were excavated in heavily over-consolidated alluvium. The excavations were supported with heavy soldier piles with pre-loaded steel-pipe struts. When measured strut loads increased to up to 3 times the design value, and strut-waler connections began to buckle, the contractor was directed to install additional struts. Maintaining that the problem had been caused by inadequate construction means and methods, the owner denied a change-order request for this work. This paper describes the contractor’s investigation into the cause of strut overloading in preparation for a formal hearing by a Dispute Resolution Board. The study concluded that the extremely high bracing loads were caused by high in-situ stresses in the region, which had not been accounted for in the shoring-pressure diagrams provided in the contract drawings.