Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Abstract

The innovative analysis, design, and construction of the temporary support of excavation (SOE) system for an underground garage will be presented in this paper. The site of the project is blanketed with a 10 to 18 feet thick layer of fill material, underlain with about 5 feet of soft organic deposits. The main soil deposit at the site consists of 65 to 90 feet deep marine clay, known as the “Boston Blue Clay”. The upper 10 to 12 feet of this clay is weathered and hardened to form a stiff crust that softens with depth. The majority of the excavation within the project site removed the stiff clay crust to expose the soft clay layer. In order to excavate to the required depth of about 44 feet, the contractor had to address a major challenge of controlling the basal heave as well as the lateral support of the excavation. Reinforced concrete slurry walls were installed along the perimeter of the underground garage to serve as structural wall and water cut-off for the parking garage. The slurry wall was toed in the soft clay layer at about 12 to 20 feet below the bottom of excavation. Finite element models that accounted for soil non-linearity were used to analyze the staged excavation and construction of the garage structure. Based on the finite element analyses, two temporary bracing levels were used to provide lateral support for the slurry walls. Because of the geometry of the underground garage and the variation of the bottom of excavation, the design and installation of the temporary bracing system was a challenging task. A close correlation between the predicted and the measured lateral deflection of the slurry wall was observed.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

Share

 
COinS
 
Apr 13th, 12:00 AM Apr 17th, 12:00 AM

Support of Deep Excavation in Soft Clay: A Case History Study

New York, New York

The innovative analysis, design, and construction of the temporary support of excavation (SOE) system for an underground garage will be presented in this paper. The site of the project is blanketed with a 10 to 18 feet thick layer of fill material, underlain with about 5 feet of soft organic deposits. The main soil deposit at the site consists of 65 to 90 feet deep marine clay, known as the “Boston Blue Clay”. The upper 10 to 12 feet of this clay is weathered and hardened to form a stiff crust that softens with depth. The majority of the excavation within the project site removed the stiff clay crust to expose the soft clay layer. In order to excavate to the required depth of about 44 feet, the contractor had to address a major challenge of controlling the basal heave as well as the lateral support of the excavation. Reinforced concrete slurry walls were installed along the perimeter of the underground garage to serve as structural wall and water cut-off for the parking garage. The slurry wall was toed in the soft clay layer at about 12 to 20 feet below the bottom of excavation. Finite element models that accounted for soil non-linearity were used to analyze the staged excavation and construction of the garage structure. Based on the finite element analyses, two temporary bracing levels were used to provide lateral support for the slurry walls. Because of the geometry of the underground garage and the variation of the bottom of excavation, the design and installation of the temporary bracing system was a challenging task. A close correlation between the predicted and the measured lateral deflection of the slurry wall was observed.