Measuring Temperature and Soil Properties for Finite Element Model Verification

AIDC project number: RR08.11


Margaret Darrow (UAF)

  • US Department of Transportation (RITA)
  • Alaska Department of Transportation & Public Facilities
  • Start Date: Feb 15, 2009
  • End Date: Aug 15, 2009

Project Summary

In recent years, ADOT&PF personnel have used TEMP/W, a commercially available two-dimensional finite element program, to conduct thermal modeling of various embankment configurations in an effort to reduce the thawing of ice-rich permafrost through thermally stable embankment designs. This modeling was done with historic air temperature data and input parameters derived from the literature, since site-specific data is typically not available. The overall goal of this study was to verify the thermal modeling results produced by TEMP/W. Temperatures and soil properties were measured at two different sites underlain by permafrost in Interior and Southcentral Alaska. A sensitivity analysis of certain input parameters was conducted on models of each site. Analysis indicates that the most critical input parameter is air temperature. While historic air temperature data provided an approximation of the regional climate, this data produced model results that were too cold by several degrees. Using air temperatures measured at each site resulted in models that closely matched the measured soil temperatures, and either matched or overestimated active layer depths. Using the overestimated active layer depth for design purposes would result in a more conservative embankment construction, which is a favorable approach if a warming climate is considered.