Location
St. Louis, Missouri
Date
03 Jun 1993, 10:30 am - 12:30 pm
Abstract
A case history and analysis are presented of a 76-foot deep braced excavation in competent silt- and claystone formations. Soldier piles and lagging were supported by three levels of struts above three levels of tie-backs. During construction, measured strut loads exceeded design levels by up to 100 percent, and additional struts were installed in the upper portion of the excavation. Back analysis performed after construction indicated that large horizontal insitu stresses (Ko= 1) in the region had contributed to the overloading. It was also shown that the problem had been compounded by the practice of pre loading the struts upon installation. The analysis further indicated that for excavations in competent, rock-like materials, excess strut loads can be safely relieved by allowing small elastic deflections of the excavation walls to take place. A simple design scheme is suggested which would allow such deformations without adversely affecting the overall performance of the excavation support system.
Department(s)
Civil, Architectural and Environmental Engineering
Meeting Name
3rd Conference of the International Conference on Case Histories in Geotechnical Engineering
Publisher
University of Missouri--Rolla
Document Version
Final Version
Rights
© 1993 University of Missouri--Rolla, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Roth, Wolfgang; Stirbys, Anthony; de Rubertis, Corbin; and Ellis, Richard, "Performance of a Braced Excavation in Siltstone" (1993). International Conference on Case Histories in Geotechnical Engineering. 21.
https://scholarsmine.mst.edu/icchge/3icchge/3icchge-session05/21
Performance of a Braced Excavation in Siltstone
St. Louis, Missouri
A case history and analysis are presented of a 76-foot deep braced excavation in competent silt- and claystone formations. Soldier piles and lagging were supported by three levels of struts above three levels of tie-backs. During construction, measured strut loads exceeded design levels by up to 100 percent, and additional struts were installed in the upper portion of the excavation. Back analysis performed after construction indicated that large horizontal insitu stresses (Ko= 1) in the region had contributed to the overloading. It was also shown that the problem had been compounded by the practice of pre loading the struts upon installation. The analysis further indicated that for excavations in competent, rock-like materials, excess strut loads can be safely relieved by allowing small elastic deflections of the excavation walls to take place. A simple design scheme is suggested which would allow such deformations without adversely affecting the overall performance of the excavation support system.
