WSDOT Foundation and Fill Settlement Case Histories

Estimation of settlement below foundations and embankment fills is a routine geotechnical design
requirement. A couple of settlement estimation methods are typically used for this purpose nationally and at
WSDOT. These include the Hough and Schmertmann methods. This report provides a summary of these
methods, and an assessment of their accuracy through comparison of predicted and measured settlement
values. Based on long-term experience, it is usually assumed that settlement estimates are not reliable enough
to predict settlements of less than 0.5 inch. The available data appear to support this in that the scatter in the
measured settlement is greater than the settlement prediction for settlements of less than 0.5 inch.

The scope of this research is limited to sandy WSDOT sites where settlement was measured (i.e.,
settlement in clay is not included). Measured settlements ranged from 0.5 inch to 40 inches.

Overall, the Hough Method provided a more accurate prediction than did the Schmertmann Method.

Publication Date: 
Saturday, August 11, 2018
Publication Number: 
WA-RD 884.1
Last modified: 
09/27/2018 - 12:13
Authors: 
Tony M. Allen
Originator: 
Washington State Department of Transportation. State Materials Laboratory.
Number of Pages: 
178
Subject: 
Foundations, Fills, Settlement (Structures), Embankments, Components of embankments and retaining walls, Geotechnical engineering, Case studies, Sandy soils, Measurement of specific phenomena, Estimating, Accuracy, Mathematical prediction.