Abstract

Permafrost creates special engineering problems for the design, construction and problems for the design, construction and maintenance of embankments. Lack of knowledge about permafrost and environmental conditions has resulted in tremendous maintenance costs as well as relocation or abandonment of highways, railroads and other embankment structures. Therefore, careful consideration must be given to the design and construction of embankments to be placed on permafrost.

Since the spring of 1969, ARCO Chemical Company has been working on embankment design and construction methods which could serve as alternates to the conventional (5–6 feet of gravel) method of embankment construction on the North Slope. Study and research has resulted in the development of ARCOFOAM Insulated Embankment Systems which are technically (thermally and structurally) capable of being used as an alternate method in the design and construction of Arctic Embankments.

Introduction

The problems of permafrost degradation must be considered in the design of Arctic and sub-Arctic embankments. Two basic design methods which may be utilized are the active and passive techniques. The active method eliminates the permafrost by excavation and fill. An example would be stage construction of sub-Arctic roadways. These are built by placement of fill and constant maintenance placement of fill and constant maintenance over a period of years as melt and subsidence of the permafrost occurs. On the North Slope of Alaska, which is underlaid with more than 1,000 feet of permafrost, the active method is impractical. The passive method prevents permafrost degradation by keeping prevents permafrost degradation by keeping it in a continually frozen state so there will be no melt and subsequent subsidence. Therefore, the passive method controls the design of roads, airfields and other embankments in the Arctic.

Subsurface features of prime concern in Arctic embankment work include soil type, water content, permafrost which, when melted, causes subsidence or settlement.

We can establish the mean annual air temperature, mean annual air freezing index, mean annual air thawing index and the amplitude of temperature fluctuation however, thermal design is related to the temperature that occurs at the soil-air interface. This temperature is affected by numerous items, such as depth of snow, soil type, wind and evaporation cooling rates at the interface.

This content is only available via PDF.
You can access this article if you purchase or spend a download.