20 YEAR PERFORMANCE HISTORY OF FIRST INSULATED ROADWAY ON PERMAFROST IN ALASKA
In 1969, extruded polystyrene foam insulation layers were experimentally installed beneath a new section of the Edgerton highway constructed over warm (-1 OC) permafrost soils near Chitina, Alaska This was the f i s t such installation in North America for preventing or controlling thawing of permaf...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.561.2871 http://pubs.aina.ucalgary.ca/cpc/cpc5-403.pdf |
| Summary: | In 1969, extruded polystyrene foam insulation layers were experimentally installed beneath a new section of the Edgerton highway constructed over warm (-1 OC) permafrost soils near Chitina, Alaska This was the f i s t such installation in North America for preventing or controlling thawing of permafrost foundation soils beneath a roadway. Periodic monitoring of temperatures, thaw depths, and settlements has continued since construction. In 1989 this installation reached its theoretical 20-year "design life", and the performance history has been reviewed and summarized as reported in this paper. The polystyrene insulation placed in 1969 beneath the new road embankment was very effective in reducing road surface settlements. particularly for the fist years after construction. Over time, the annual settlement rates in the insulated areas have accelerated, but insulated area road surface settlement rates have never reached the rates observed on the adjacent uninsulated road sections. Because of the warming influence of the roadway and particularly the side-slopes, progressively deeper annual warming and thawing is now acting to undermine the entire embankment, in spite of the fact that the insulation was extended out to the lateral limits of the embankment. Talik zones below the slopes grow in depth and lateral extent each year. and after 20 years have progressed to where they are affecting even the center of this relatively narrow (8 m |
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