An Approach to Applying Spring Thaw Load Restrictions for Low Volume Roads Based on Thermal Numerical Modelling

Jurisdictions in Canada and the northern United States apply spring load restrictions (SLRs) to low volume roads to mitigate damage to these roads during spring thaw. Ideally, the SLRs should commence when the thaw front has begun to penetrate sub-base materials, and end when the pavement system is completely thawed (Andersland and Ladanyi, 2004). Methods involving visual observations, field testing, prescheduled dates and empirical models are currently being used to apply SLRs. These methods, however, do not readily allow variations in climatic conditions and pavement system properties, such as soil type and water content, to be accounted for in a comprehensive manner. To this end, thermal numerical modeling is being conducted for the purpose of developing guidelines to apply SLRs. Time variations of frost and thaw depths were simulated using the finite element thermal model TEMP/W (by GEO-SLOPE International Ltd.) and are compared with measured frost and thaw depths at an instrumented site in northern Ontario. A particular focus of this work is on the thermal boundary conditions applied at the upper and lower boundaries of the thermal model. Modeling results to date indicate that penetration of the frost front over the winter can be simulated fairly well, with a good match to the measured results. Modeling the thaw front penetration was found to be quite dependent on the upper thermal boundary condition. An approach in which an “n-factor” is used to estimate pavement surface temperatures from measured air temperatures best simulates the measured progression of the thaw front. A floating reference temperature approach, to better account for increasing solar gain during the spring thaw period, is also examined.

Language

  • English

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 496-505
  • Monograph Title: Cold Regions Engineering 2009. Cold Regions Impact on Research, Design and Construction

Subject/Index Terms

Filing Info

  • Accession Number: 01144183
  • Record Type: Publication
  • ISBN: 9780784410721
  • Files: TRIS
  • Created Date: Nov 17 2009 11:13AM