Mechanics of Lake Ice - Freezing of Lakes and the Evolution of their Ice Cover - page 156

Fig. 5.10 ' Ice quakes ' were felt in the houses close to the shore due to pressure by strong wind

Example 5.5. Thermal pressure. In Lake Mälaren, Sweden thermal pressure has caused
damage in the past (Bergdahl and Wernersson 1978). In winter 1953 a swing bridge was
partly damaged. Air temperature rose by 14 °C in 12 h and 22 cm thick ice expanded and
pressed toward the bridge. The forcing was estimated as 270 kN m − 1 . In winter 1976 four
beacons mounted on pile groups were destroyed by thermal expansion, with pressures
estimated as 100 270 kN m − 1 .

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5.4.2 Estimation of Ice Loads

The load of ice on structures depends on the mode of loading, strength of the structure,
and form of the structure. The fundamental method to evaluate ice loads is the Korzhavin
(1962) equation for vertical structures:

F ¼ Ik 1 k 2 r Dh ð 5 : 31 Þ

where I is the indentation factor, k 1 , k 2 and D are the contact factor, shape factor and width
of the structure, and

σ

and h are the strength and thickness of ice. The indentation factor
I accounts for the 3D nature of the stress in ice representing the stress-strain

field around
the structure and accounting for the difference between the real and the unconfined stress