222
Climatic Geomorphology
175- Abutment Pier
Pier Abutment
0
1
2
3
4
ace position
-...-E"
'f~.~.v' .~_ ~,,~
1[ ~
.....t~-.Permafrost limit
-
..~.t',~ "
E
~
~
"
,'.-_,L='
E
155 Permafrost
"-'-',';"" ~'"",
~ 60
10
20
30m
03
13 12 1
2
3
4 5
m
mm
m
m
I
I
-Murphy ~)ome
11 10
9
8
7 6
10'.'I_
l
I
1
-
-.. ... ,, ,....,, ,, ...1 ,.....,.., ....
"':':'.'i'-.-" "'-\
i \
i
-
\, ,\
"'9 "\
\, j~, -
1965I 19t361 19671 1968 I 1969
Figure 9.11. Cross section of the Goldstrean Creek Bridge and displacement through time of some piers
(Crory, 1985; in Harris (1986), Figure 5.9).
4.3. Oil and gas pipelines
Pipelines are relatively abundant in periglacial regions such as Siberia, Canada and
Alaska. The most well known one is the 1300-km long Trans-Alaskan Pipeline that was
built after the discovery of a large oil field in 1968. It starts in Prudhoe Bay, on the arctic
coast, and finishes in Valdez in the Alaska Gulf. The oil is transported by ship from this
harbour to refineries located in the western coast of the United States and in Japan. The
pipeline was built between 1969 and 1977 at a final cost of 7000 million dollars, eight
times higher than the initial estimate. About 70 % of the pipeline was built on permafrost
zones (Harris, 1986).
Numerous and complex problems were faced during the construction of the TransAlaskan Pipeline. One of the most relevant ones was related to the temperature of the oil
that was introduced into the pipe at 58~ A pipeline buried beneath the surface and
transporting hot fluids causes the thawing of the permafrost. With no protection measures,
the thawing of the permafrost expands through time around the pipe (Lachenbruch, 1970)
(Figure 9.12). The speed of the thawing expansion decreases with time and never reaches
an equilibrium state. Consequently, the ground progressively looses its mechanical
strength and eventually is unable to support the pipe. The lack of bearing capacity of the
ground leads to the generation of settlements at the surface and deformations in the pipe. In
addition, differential uplifts and settlements are very common and of variable magnitude
as the pipes cross zones with different types of material. Where it crosses ice wedges the
detrimental effects due to thawing occur rapidly. Additional problems also rose from the
destruction of the vegetation cover during the construction (Ritter, 1978).
Climatic Geomorphology
175- Abutment Pier
Pier Abutment
0
1
2
3
4
ace position
-...-E"
'f~.~.v' .~_ ~,,~
1[ ~
.....t~-.Permafrost limit
-
..~.t',~ "
E
~
~
"
,'.-_,L='
E
155 Permafrost
"-'-',';"" ~'"",
~ 60
10
20
30m
03
13 12 1
2
3
4 5
m
mm
m
m
I
I
-Murphy ~)ome
11 10
9
8
7 6
10'.'I_
l
I
1
-
-.. ... ,, ,....,, ,, ...1 ,.....,.., ....
"':':'.'i'-.-" "'-\
i \
i
-
\, ,\
"'9 "\
\, j~, -
1965I 19t361 19671 1968 I 1969
Figure 9.11. Cross section of the Goldstrean Creek Bridge and displacement through time of some piers
(Crory, 1985; in Harris (1986), Figure 5.9).
4.3. Oil and gas pipelines
Pipelines are relatively abundant in periglacial regions such as Siberia, Canada and
Alaska. The most well known one is the 1300-km long Trans-Alaskan Pipeline that was
built after the discovery of a large oil field in 1968. It starts in Prudhoe Bay, on the arctic
coast, and finishes in Valdez in the Alaska Gulf. The oil is transported by ship from this
harbour to refineries located in the western coast of the United States and in Japan. The
pipeline was built between 1969 and 1977 at a final cost of 7000 million dollars, eight
times higher than the initial estimate. About 70 % of the pipeline was built on permafrost
zones (Harris, 1986).
Numerous and complex problems were faced during the construction of the TransAlaskan Pipeline. One of the most relevant ones was related to the temperature of the oil
that was introduced into the pipe at 58~ A pipeline buried beneath the surface and
transporting hot fluids causes the thawing of the permafrost. With no protection measures,
the thawing of the permafrost expands through time around the pipe (Lachenbruch, 1970)
(Figure 9.12). The speed of the thawing expansion decreases with time and never reaches
an equilibrium state. Consequently, the ground progressively looses its mechanical
strength and eventually is unable to support the pipe. The lack of bearing capacity of the
ground leads to the generation of settlements at the surface and deformations in the pipe. In
addition, differential uplifts and settlements are very common and of variable magnitude
as the pipes cross zones with different types of material. Where it crosses ice wedges the
detrimental effects due to thawing occur rapidly. Additional problems also rose from the
destruction of the vegetation cover during the construction (Ritter, 1978).