TM 5-852-1/AFR 88-19, Volume 1
(2) Subarctic. The region adjacent to the
Arctic in which the mean temperature for the coldest
This manual contains general criteria and information for
month is below 32F, the mean temperature for the
considering frost action, permafrost and other factors in
warmest month is above 50F, and in which there are
the design of military facilities in arctic and subarctic
less than 4 months having a mean temperature above
50F. In general, subarctic land areas coincide with the
circumpolar belt of dominant coniferous forest.
(3) Seasonal frost areas. Those areas of
The contents of this manual are applicable to both Army
the earth in which there is significant freezing during the
and Air Force construction. This manual provides basic
.winter but without development of permafrost.
background data for the detailed criteria pertaining to the
b. Soil and frost terms.
various elements of arctic and subarctic facility design
(1) Active layer. A commonly used term in
presented in the other manuals of the Arctic and
permafrost areas for the annual frost zone.
Subarctic Construction series, TM 5-852-2 through 7,
(2) Aggradation. Progressive raising of
and 9/AFR 88-19, Volume 2, 5 and 6/AFM 88-19, Chap.
the permafrost table, taking place over a period of years.
3, 4, 7, and 9.
(3) Annual frost zone. The top layer of
ground subject to annual freezing and thawing. In arctic
Need for special approaches
and subarctic regions where annual freezing penetrates
In the design, construction and maintenance of facilities
to the permafrost table, the active layer, suprapermafrost
such as roads, utilities and buildings in arctic and
and the annual frost zone are identical.
subarctic regions, many problems are encountered that
(4) Closed system. A condition in which
(do not exist, or are not present in the same degree, in
no source of free water is available during the freezing
more temperate regions. These problems arise, for
process beyond that contained originally in the voids of
example, from the presence of permafrost over vast
areas, with its potential for thaw and thaw settlement;
Extremely slow, continuing
from the special properties of frozen soil, frozen rock and
strain deformation of material under stress, at rates so
ice; from the effects of frost heave and other phenomena
slow as to usually be imperceptible except by
in soil, rock, paving and other materials subject to
observations of high precision or of extended duration.
intense annual cycles of freezing and thawing
(6) Degradation. Progressive lowering of
temperatures; from drainage, water supply and
the permafrost table, occurring over a period of years.
sewerage problems peculiar to those regions; and from
(7) Excess ice. Ice in excess of the
such factors as the shortness of the above-freezing
fraction that would be retained as water in the soil voids
summer season, the limited amount of daylight in fall and
winter, environmental aspects, and often difficult
(8) Frost action.
A general term for
freezing and thawing of moisture in materials. It also
Special design, construction and
covers the effects on these materials and on structures
maintenance approaches, and management of
of which they are a part or with which they are in contact.
construction are often required to cope with such
The term "frost" is often used to refer to frost action in
problems and to meet stability and operational
requirements for facilities.
(9) Frost boil. The breaking of a limited
section of a highway or airfield pavement under traffic
and ejection of soft, semi-liquid subgrade soil. This is
Certain specialized terms used in current literature on
caused by the melting of the segregated ice formed by
frost and permafrost and in the Arctic and Subarctic
Construction manuals are defined below. Additional
terms pertinent to heat transfer calculations are defined
downslope movement of particles as a result of frost
in TM 5-852-6/AFR 88-19, Volume 6.
heaving and subsequent ground settling upon thawing.
The heaving is predominantly normal to the slope and
(1) Arctic. The northern region in which
the settling more nearly vertical.
the mean temperature for the warmest month is less
(11) Frost heave. The raising of a surface
than 50F and the mean annual temperature is below
because of ice formation in the underlying soil.
In general, the arctic land areas coincide
(12) Frost slough. A shallow slide that
approximately with the tundra region north of the limit of
occurs when the stability of frost-loosened and