Geology Reference
In-Depth Information
Table 14.1. The percentage of buildings that, on engineering grounds, are regarded as having
already failed, or will fail, between 1900 and 2030, classifi ed according to the year of initial
commission, in Central Siberia.
City, year of
Year of predicted failure
construction
1990
2000
2010
2020
2030
Vorkut a :
1950
10
18
39
44
60
1960
9
17
31
43
60
1970
7
15
29
42
59
1980
3
12
26
40
57
1990
0
9
24
38
56
Tiksi:
1950
9
23
63
90
98
1960
7
20
62
90
98
1970
4
18
61
90
98
1980
2
16
60
90
98
1990
0
14
60
90
97
Ya k ut sk:
1950
8
28
72
94
100
1960
6
27
72
94
100
1970
4
25
71
94
100
1980
2
24
71
94
100
1990
0
22
70
94
100
Source: Khrustalev (2000).
14.6. ROADS, BRIDGES, RAILWAYS, AND AIRSTRIPS
Road construction in periglacial environments is no more diffi cult than elsewhere if there
is an abundant supply of coarse, non-frost-susceptible aggregate for the roadbed. Unfor-
tunately, this is not always the case because many areas lack either glacial outwash depos-
its or are distant from alluvial gravels. The result is that crushed bedrock is often hauled
from distant sources to prevent the inevitable frost heaving that would occur if less suita-
ble, but more local, materials were used. Gravel surfaces are the norm for many parts of
Alaska, northern Canada, northern Russia, and northern Scandinavia. Black-topping
(asphalt) is deliberately avoided except in the towns in order to reduce solar heat absorp-
tion. The most common technique is for the gravel pad to be placed directly upon the
undisturbed ground surface by front-end loading.
A specifi c hazard as regards highway and railway construction relates to the formation
of groundwater icings (see Chapter 5). They were fi rst encountered during the building
of the Alaskan Highway (Péwé, 1983c, pp. 74-80; Thomson, 1966). These are most
common in the discontinuous permafrost zone where a road cutting, or any other man-
made excavation, intersects with the supra-permafrost groundwater table. Groundwater
seepage forms a sheet of ice, often several tens of square meters in extent. Unless precau-
tions are taken, icings can occur on most northern highways wherever they traverse sloping
terrain. Counter measures include the avoidance of road-cuts wherever possible, the
installation of high-arch culverts to divert water from the source of the icing, and the
 
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