Page 246 - Geotechnical Engineering Soil and Foundation Principles and Practice

Pore Water Pressure, Capillary Water, and Frost Action
Pore Water Pressure, Capillary Water, and Frost Action 241

Figure 11.21
Schematic diagram
showing method
for preservation of
permafrost under
the Trans-Alaska
pipeline.

barrier to water seeping through the active zone, leading to ponding on the uphill
side of the road. Culverts should be large enough to allow flow of air and thawing
during summer months.

Tundra of the high Arctic is marshy and supports a variety of mosses, lichens,
flowers, and shrubs that are part of the eco-chain, are easily damaged, and are
very slow to recover. Most land travel therefore is during winter when the tundra
is frozen.

11.10.8 Cold-Storage Plants
Cold-storage facilities simulate Arctic conditions and gradually create a perma-
frost bulb and frost heave. An air space or auxiliary subfloor heating system
separated from the cold room by insulation can avoid such eventualities.

Shutting down a frost-heaved cold-storage facility can create another set of
problems as thawing of ice lenses leads to soft ‘‘frost boil’’ soil conditions under
the floor and footings. It is not unusual to find older facilities for sale.

11.10.9 Insulation to Prevent Thawing or Freezing
If a mean temperature is above or below freezing, insulation alone will not prevent
ground thawing or freezing, respectively, but will only delay it. Insulation can be
effective during a single cycle, for example to prevent frost heave during a single
winter season, but will not solve a permafrost problem if the overall direction of
heat flow is not changed. A method that is successful for relatively small buildings

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