TM 5-852-4/AFM 88-19, Chap. 4
U. S. Army Corps of Engineers
Figure 2-9c. Maximum Frost Heave Pressures. (Grain, Size Distribution, of Soils.)
areas, layers of salty groundwater and unfrozen strata
dependent on such variables as gradation, density,
208
may be encountered in the soils . Methane pockets
degree of saturation, ice content, temperature,
are common because of entrapment by the impervious
percentage of moisture in specimen frozen, dissolved
frozen soil, and animal and vegetative remains are often
solids, and rate of loading. Available data on effect of
found surprisingly intact, their decomposition rates
rate of loading on strength of frozen materials are
slowed in the permafrost. Organic soils are common,
summarized
in
figure
2-14.
Frozen
soils
both in permafrost and seasonal frost zones. Organic
characteristically exhibit creep at stresses as low as 5 to
53,187
.
soils range from only slightly organic mineral soil to 100
10 percent of the rupture strength in rapid loading
Typical creep relationships are shown in figure 2-15.
percent organic muskeg or peal. They cover about 10
(4) The effect of ice content on the
percent of the land area of Alaska and present both
189
transportation and construction obstacles .
compressive strength of Manchester fine sand is shown
(2) Figure 2-10 shows typical compressive
in figure 2-16.
strength values for nine types of frozen soil including
(5) Values of dynamic moduli and Poisson's
peat, in laboratory tests performed at 400 psi/min rate of
ratio determined by flexural vibration are summarized in
68
figure 2-17 . See also paragraph 4-6. Values of
stress increase.
Properties of these soils are
adfreeze strength for tangential shear on various
summarized in figure 2-11. Figure 2-12 presents a
materials are discussed in paragraph 4-8.
similar summary for tension tests performed on these
(6) It will be apparent
from
the
soils at a rate of stress increase of 40 psi/min. Figure 2-
information presented above that it is not feasible to give
13 shows a summary for shear tests performed at a rate
categorical
of stress increase of 100 psi/min.
(3) Strength properties of frozen ,oils are
2-13
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