Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

The paper describes the design and construction history of 67-story and 45-story residential towers in Chicago which were constructed on straight-shaft caissons supported on the surface of dolomite bedrock at a design bearing pressure of 90 tons per square foot (tsf). The use of the 90 tsf bearing pressure was a first in Chicago and a strong departure from the Chicago code method of requiring rock sockets at least one to six feet deep along with permanent steel casing. The caissons were constructed by using polymer drilling slurry and tremie concrete pouring procedures. This paper presents a brief history and evolution of the Chicago caisson to provide context to the project design and describes the load testing program used to prove the design and performance of the foundations. The non-destructive testing and coring programs used to check the concrete quality identified defects in several shafts which required remediation. The methods used to remediate the defective shafts included pressure grouting, shaft replacement, and large-strain dynamic load testing.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

Slurry Caisson Problems and Correction in Chicago

Chicago, Illinois

The paper describes the design and construction history of 67-story and 45-story residential towers in Chicago which were constructed on straight-shaft caissons supported on the surface of dolomite bedrock at a design bearing pressure of 90 tons per square foot (tsf). The use of the 90 tsf bearing pressure was a first in Chicago and a strong departure from the Chicago code method of requiring rock sockets at least one to six feet deep along with permanent steel casing. The caissons were constructed by using polymer drilling slurry and tremie concrete pouring procedures. This paper presents a brief history and evolution of the Chicago caisson to provide context to the project design and describes the load testing program used to prove the design and performance of the foundations. The non-destructive testing and coring programs used to check the concrete quality identified defects in several shafts which required remediation. The methods used to remediate the defective shafts included pressure grouting, shaft replacement, and large-strain dynamic load testing.