216
Climatic Geomorphology
railways, pipelines, etc., is one of the main causes of the alteration of the permafrost.
Important disturbances may also be due to changes in the natural hydrological conditions
produced by the diversion of rivers, construction of reservoirs, or desiccation of peat bogs
(Haugen and Brown, 1971). The main effect derived from these activities is the
degradation of the permafrost, usually an irreversible process. The frozen ground, due to
its low heat conductivity, needs years or decades to attain the equilibrium for the new
thermal conditions imposed by the man action (Cooke and Doorkamp, 1990).
The study of the permafrost areas before the development of any activity capable of
disturbing the equilibrium of the frozen ground may help to avoid problems and generate
substantial cost savings. The analysis of the area of interest with aerial photographs allows
us to differentiate types of ground based on criteria like the vegetation that reflects soil
characteristics such as moisture content and texture. Subsequently, field studies should be
carried out to examine the distribution and nature of the permafrost and the active layer,
drainage characteristics of the ground, surficial materials, temperature and humidity of the
soil and atmosphere, and other features (Cooke and Doornkamp, 1990).
The methods used for the avoidance and mitigation of geotechnical problems are
classified into active and passive (Muller, 1945). In ground sensitive to thaw passive
methods are the most frequently used. These methods are based on keeping the materials
in their initial thermal state to avoid settlements. The active methods generally involve the
replacement of the material sensitive to the freezing by others more resistant to this
process. Additionally, structures capable of resisting the stresses derived from alterations
in the thermal regime causing heaving and settlement deformations are also designed.
4.1. Buildings
The first constructions in periglacial regions were founded on wooden piles as basements.
From the use of concrete for the supporting structures, numerous buildings started to be
affected by cracks and differential settlements (Harris, 1986). One of the most outstanding
examples of construction problems in permafrost areas is Atlavik village in the Mackenzie
River Delta (Cooke and Doornkamp, 1990; French, 1996). The village was founded in
1912, and in 1950 the permanent population reached 400 people, rising to 1500 in summer
with the arrival of Eskimos and Indians. The later growth of the village with the use of
inadequate construction techniques entailed numerous stability problems in the buildings.
Atlavik was settled on fine-grained and poorly-drained deltaic sediments with a high
proportion of interstitial ice. The new development caused local uplifts and settlements in
the ground and the generation of flood-prone depression. The adverse situation led to the
abandonment of the site and its relocation in an emplacement with more suitable
geotechnical conditions. The construction of a new village called Inuvik, 48 km away
from Atlavik, started in 1955 and at the present time is inhabited by some 1500 people.
The selection of the site, that combines all the suitable conditions for the foundation of a
new locality, was based on detailed studies. This example demonstrates the need of having
a precise knowledge of the permafrost dynamics and its local conditions for the avoidance
of damages in buildings.
The capacity of the ground to bear a load without undergoing deformation depends on
the type of material and may change significantly during the freezing and thawing periods
Climatic Geomorphology
railways, pipelines, etc., is one of the main causes of the alteration of the permafrost.
Important disturbances may also be due to changes in the natural hydrological conditions
produced by the diversion of rivers, construction of reservoirs, or desiccation of peat bogs
(Haugen and Brown, 1971). The main effect derived from these activities is the
degradation of the permafrost, usually an irreversible process. The frozen ground, due to
its low heat conductivity, needs years or decades to attain the equilibrium for the new
thermal conditions imposed by the man action (Cooke and Doorkamp, 1990).
The study of the permafrost areas before the development of any activity capable of
disturbing the equilibrium of the frozen ground may help to avoid problems and generate
substantial cost savings. The analysis of the area of interest with aerial photographs allows
us to differentiate types of ground based on criteria like the vegetation that reflects soil
characteristics such as moisture content and texture. Subsequently, field studies should be
carried out to examine the distribution and nature of the permafrost and the active layer,
drainage characteristics of the ground, surficial materials, temperature and humidity of the
soil and atmosphere, and other features (Cooke and Doornkamp, 1990).
The methods used for the avoidance and mitigation of geotechnical problems are
classified into active and passive (Muller, 1945). In ground sensitive to thaw passive
methods are the most frequently used. These methods are based on keeping the materials
in their initial thermal state to avoid settlements. The active methods generally involve the
replacement of the material sensitive to the freezing by others more resistant to this
process. Additionally, structures capable of resisting the stresses derived from alterations
in the thermal regime causing heaving and settlement deformations are also designed.
4.1. Buildings
The first constructions in periglacial regions were founded on wooden piles as basements.
From the use of concrete for the supporting structures, numerous buildings started to be
affected by cracks and differential settlements (Harris, 1986). One of the most outstanding
examples of construction problems in permafrost areas is Atlavik village in the Mackenzie
River Delta (Cooke and Doornkamp, 1990; French, 1996). The village was founded in
1912, and in 1950 the permanent population reached 400 people, rising to 1500 in summer
with the arrival of Eskimos and Indians. The later growth of the village with the use of
inadequate construction techniques entailed numerous stability problems in the buildings.
Atlavik was settled on fine-grained and poorly-drained deltaic sediments with a high
proportion of interstitial ice. The new development caused local uplifts and settlements in
the ground and the generation of flood-prone depression. The adverse situation led to the
abandonment of the site and its relocation in an emplacement with more suitable
geotechnical conditions. The construction of a new village called Inuvik, 48 km away
from Atlavik, started in 1955 and at the present time is inhabited by some 1500 people.
The selection of the site, that combines all the suitable conditions for the foundation of a
new locality, was based on detailed studies. This example demonstrates the need of having
a precise knowledge of the permafrost dynamics and its local conditions for the avoidance
of damages in buildings.
The capacity of the ground to bear a load without undergoing deformation depends on
the type of material and may change significantly during the freezing and thawing periods