Remediation of Anomalous Drilled Shafts–A Case Study

A case history is presented of drilled shaft foundations found to have anomalous concrete and, in some cases, structural deficiencies. The process that was implemented in response to the anomalies and deficiencies provides an illustrative example of how post-installation problems can be addressed effectively in order to ensure that foundation design criteria are satisfied. The project involved drilled shafts for the goethals bridge replacement (GBR), a dual-span cable-stayed bridge crossing the Arthur Kill between Elizabeth, NJ and Staten Island, NY supported on over 200 rock-socketed drilled shaft foundations. The drilled shafts that are the subject of this paper are located in a section of the Eastbound bridge starting at the west abutment (NJ side) and including the next four piers east of the abutment. All of the subject shafts are 4.5-ft diameter with permanent casing to rock and 4-ft diameter rock sockets. Following construction, cross-hole sonic logging (CSL), and tomography (CT) identified anomalous readings in 16 of the 23 shafts. All of the anomalies were located in the rock-socketed portion of the shafts near the tip. Based on the severity of the anomalies and evaluation of geotechnical and structural demands, two of the anomalous shafts were accepted without additional investigation. The remaining 14 shafts were investigated by concrete coring. Based on the coring results and further analyses, seven additional shafts were accepted without further action. The remaining seven shafts were repaired by using hydro-demolition to remove defective concrete followed by replacement with grout. This paper describes the process used to characterize and evaluate the nature of potential defects in each shaft and how that formed a basis for decisions on whether each shaft was accepted, selected for further investigation, or designated for repair. The repair process, including quality control, and quality assurance procedures, is presented in detail. Lessons learned and their application to future projects are presented.

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  • Supplemental Notes:
    • © 2018 American Society of Civil Engineers.
  • Corporate Authors:

    American Society of Civil Engineers

    New York, New York  United States 
  • Authors:
    • Daita, Bobby
    • Turner, John P
    • Beeks, Brannin . J
  • Conference:
    • IFCEE 2018
    • Location: Orlando Florida, United States
    • Date: 2018-3-5 to 2018-3-10
  • Publication Date: 2018-6

Language

  • English

Media Info

  • Media Type: Web
  • Features: References;
  • Pagination: pp 21-36
  • Monograph Title: IFCEE 2018: Recent Developments in Geotechnical Engineering Practice

Subject/Index Terms

Filing Info

  • Accession Number: 01684401
  • Record Type: Publication
  • ISBN: 9780784481622
  • Files: TRIS, ASCE
  • Created Date: Oct 4 2018 4:59PM