A Deep Foundation Surprise, Engineering Response, and Foundation Performance

The paper describes the foundation design and construction history of a 19-story residential high rise on deep foundations on the south side of downtown Chicago, including: a value engineering foundation design innovation; the changes in anticipated conditions actually encountered during construction; the additional subsurface exploration and special testing and new engineering analyses performed to better predict ultimate foundation performance; and the foundation design modification required to make the predicted foundation performance acceptable. The paper also presents the actual measured foundation performances, compares prediction with performance and offers possible explanations where there are significant differences. The authors note that the majority of the caissons reached refusal on a dense boulder till and did not reach the bedrock interface as anticipated in the design. The specified post construction test procedures were essential in determining that construction was not in accordance with design. The authors conclude that the criteria of drilling to earth auger refusal plus 20 minutes more with a rock auger, while not sufficient to assure bearing on rock, was adequate to assure bearing material was sufficient to carry the design loads in conjunction with the available side friction on this project.


  • English

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 262-277
  • Monograph Title: GeoSupport 2004. Drilled Shafts, Micropiling, Deep Mixing, Remedial Methods, and Specialty Foundation Systems

Subject/Index Terms

Filing Info

  • Accession Number: 01000184
  • Record Type: Publication
  • ISBN: 0784407134
  • Files: TRIS
  • Created Date: May 4 2005 8:09AM