Thermoinsulating Media within Embankments on Perennially Frozen Soil: Fid-Bau Portal

Thermoinsulating Media within Embankments on Perennially Frozen Soil

R. L. Berg

Numerous transportation facilities have been proposed for arctic and subarctic regions. Most will be constructed on embankments. Incorporation of a thermo-insulating layer within the embankment may permit use of reduced quantities of embankment material. Thermal design and analysis procedures applicable to embankments are reviewed and a two-dimensional numerical method coupling heat and mass transfer and vertical displacement is proposed. The modified Berggren equation, a method developed by Lachenbruch, and a finite difference technique are used to illustrate design and analysis methods for insulated embankments on permafrost. More than sixty thermoinsulating materials suitable for incorporation into embankments are currently available; however, only seventeen materials have been used. Most applications of insulation have been in seasonal frost areas but a few test sections have been constructed on permafrost. Stability of thermal and physical properties is a desirable characteristic of thermo-insulating layers. Moisture absorption causes increased thermal conductivity and degradation of strength of some insulating materials. Several types of moisture barriers have been used but the most successful have been polyethylene sheets. Laboratory tests presently used to evaluate properties of insulating materials do not provide quantitative design information. A new device that could provide this information is proposed. Other suggestions for future research are made. (Author)