Downdrag in Pile Design: The Positive Aspects of Negative Skin Friction

Downdrag is pile settlement in response to settlement of the surrounding soil. The bearing capacity approach to downdrag leads to erroneous design calculations and the implementation of unnecessary construction mitigation techniques. Pile settlement calculations are required to properly evaluate downdrag, but geotechnical engineers have been reluctant to use settlement calculations in pile design. When viewed from a settlement perspective, it becomes clear that downdrag is a very common phenomenon that all pile foundations experience to some degree. In fact, downdrag can limit structure settlement by pre-compressing the pile and the soil at the pile tip prior to application of the structure load. Spreadsheet calculations using Florida Department of Transportation (FDOT) FB-Deep and FB-MultiPier computations for skin friction, end bearing and pile tip movement are presented to illustrate the effect of soil settlement on pile settlement, structural integrity and bearing capacity in numerical and graphical formats.


  • English

Media Info

  • Media Type: Web
  • Pagination: pp 489-506
  • Monograph Title: From Research to Practice in Geotechnical Engineering

Subject/Index Terms

Filing Info

  • Accession Number: 01538411
  • Record Type: Publication
  • ISBN: 9780784409626
  • Files: TRIS, ASCE
  • Created Date: Jul 2 2014 3:01PM