Page 235 - Geotechnical Engineering Soil and Foundation Principles and Practice

Pore Water Pressure, Capillary Water, and Frost Action
230 Geotechnical Engineering

Figure 11.14
Two cores
showing ice
lenses that lifted
a seven-story
building in
Canada. (From
Penner and
Crawford, 1983,
National Research
Council of
Canada.)

11.8.3 Three Requirements for Frost Heave
Obviously frost heave requires cold temperatures. A second requirement is the
availability of unfrozen water, usually from a shallow groundwater table. A third
requirement is for the soil to be sufficiently permeable to transmit a damaging
amount of water during a single winter season.

Frost heave results from a potential gradient that draws water into the freezing
zone. If the freezing front remains stationary, water will continue to be drawn up
and freeze to make a layer of relatively pure ice. If the weather turns colder so that
freezing penetrates downward, it encapsulates the ice layer and prevents further
growth. Slow freezing is conducive to frost heave.

Soil and water conditions required for frost heave are as follows:
The soil must have sufficient capillary tension to draw water into the freezing
zone, which means that sands do not exhibit very much frost heave.
The soil must be sufficiently permeable that a significant amount of water can
be transferred during a winter season, which means that dense clays do not
exhibit very much frost heave.
There must be an available supply of water that normally will come from a
groundwater table.

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