Field Stiffness Reduction Evaluations from Back-Analysis of Pile Load Tests

Starting with the fundamental small-strain shear modulus (Gmax), the mechanical nonlinear stress-strain-strength behavior of soil manifests itself in the form of stiffness reduction under loading. Back analyses of 105 pile load tests combined with a knowledge of soil parameters at the site and pile geometries provide a framework for evaluation of operational stiffnesses at different levels of loading. This paper explains the framework for obtaining the operational stiffnesses from pile load tests and presents stiffness reduction curves (G/Gmax) in terms of logarithm of pseudo-strain (w/d), where w = pile displacement and d = pile diameter. The result affords an approach to evaluating the nonlinear load-displacement response of piles without resort to evaluating the pile capacity. The framework utilizes the Randolph elastic pile model to generate stiffness reduction curves from top-down axial compression load tests, tension tests, and O-cell configurations.

• Record URL:
  • https://doi.org/10.1061/9780784412121.017
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/9780784412121
• Supplemental Notes:
  • © 2012 American Society of Civil Engineers.
• Corporate Authors:

  American Society of Civil Engineers

  1801 Alexander Bell Drive
  Reston, VA  United States  20191-4400
• Authors:
  • Niazi, F S
  • Mayne, P W
• Conference:
  • GeoCongress 2012
  • Location: Oakland California, United States
  • Date: 2012-3-25 to 2012-3-29
• Publication Date: 2012-3

Language

• English

Media Info

• Media Type: Web
• Pagination: pp 155-164
• Monograph Title: GeoCongress 2012: State of the Art and Practice in Geotechnical Engineering

Subject/Index Terms

• TRT Terms: Load tests; Stiffness; Support piles
• Uncontrolled Terms: Backanalysis
• Subject Areas: Bridges and other structures; Design; Geotechnology; Highways; I24: Design of Bridges and Retaining Walls; I40: Soils and Rocks;

Filing Info

• Accession Number: 01530352
• Record Type: Publication
• ISBN: 9780784412121
• Files: TRIS, ASCE
• Created Date: Jul 14 2014 4:50PM