Current ICT Project
Investigators:
  J. Long (Primary)
Project Title:
  Evaluation/Modification of IDOT Foundation Piling Design and Construction Policy
Start Date: 1/1/2007
End Date: 3/31/2009
Summary of Project:
  Methods for determining pile length in the design phase currently used by the Illinois DOT have been used for many years, however, their origin and basis for development is undocumented. IDOT is changing their method for determining pile capacity in the field from the Engineering News formula to the more accurate FHWA-modified Gates formula. This change represents an improvement in the ability to predict capacity based on driving resistance. IDOT is also changing pile design from ASD to LRFD which affects both the static method used in design and the dynamic method used in construction. This effort will evaluate and modify the predictive methods to improve agreement between estimated pile lengths and driven pile lengths, while also evaluating data to identify resistance factors associated with pile design.
Objective of Project:
  The three main objectives for this study are 1) to quantify and improve IDOT’s method for determining pile capacity, 2) to quantify and improve IDOT’s method for estimating pile length, and 3) to quantify and improve the agreement between the length of pile estimated for a site, and the length of pile actually driven.
Expected Outcome:
  The results from this study will include the following: 1) an improved method for estimating pile length based on soil properties and the associated resistance factors for LRFD, 2) an improved method for estimating pile capacity based on behavior of the pile during driving and the associated resistance factors for LRFD, and 3) an approach using deliverables #1 and #2 that will quantify and improve the agreement between estimated pile lengths and driven pile lengths.
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Last Updated: 11/18/2009