Ice-Covered Lakes Environment - Freezing of Lakes and the Evolution of their Ice Cover - page 258

8.3.2 Ice Loads

The magnitude of ice forcing on structures can be evaluated by simpli ed analyses. The

force on a pier-type structure can be estimated by a Korzhavin (1962) type formula

F ¼ K r 0 bh ð 8 : 9 Þ

where K is a scaling coef cient, ˃ 0 is the compressive strength, b is the width of the pillar,

and h is ice thickness. The coef cient K depends on the mechanical properties of ice and

the geometry of the pier structure (Ashton 1986). For a narrow structure the ratio

ʴ = b/h is

an important parameter, K = 2.5 for 1. For wide structures and

wedge-shaped piers, K = 1 can be taken. For inclined structures K < 1 depending on the
slope angle of the structure and ice-structure friction.
Fixed structures are designed to stand for the maximum forcing, and they range from
simple docks to lighthouses. Ice load on ships provides resistance to ship

ʴ =1andK 1 for ʴ ≫

→

'

s motion and at
extreme may cause damage to ships. The resistance depends on the thickness, strength and
density of the ice, and on the size and shape and the velocity of the ship.

8.3.3 On-Ice Traffic

A stable lake ice cover has served for traf c and transportation. A 5-cm thick ice sheet is

capable to carry one person, a small car (1 ton) at 20-cm ice thickness, and a truck (10
tons) at 50-cm thickness. The bearing capacity increases proportional to the square of the
ice thickness (see Sect. 5.3 ). When the ice thickness has reached 40 cm or more, car traf c

is allowed on of cial ice roads. In Siberia, shortcut tracks for the railroad have been

constructed across rivers. For heavy steam engine locomotives (100 tons), the thickness of
ice would need to be at least 150 cm for safe crossing using the point load estimator, but
the requirement can be lowered to with wooden supports beneath the track. Also lake ice
cover has served as a runway for airplanes.
The fundamentals and the technology of ice roads and crossings under moving loads
(road, railroad, and horse-drawn transportation) were developed during the World War II,
as well as the creation of on-ice air elds. In the history a special place is occupied by the

“ , laid on the ice cover of Ladoga Lake, that played a key role in the defence

of Leningrad during the siege supplying the population with food and other essential
goods (Fig. 8.11 ) (Bregman 1943; Ivanov 1949). After the war, there were growing needs
for research of ice cover for the economic development of the northern territories, as well
as for opportunities of storage and transport of military equipment.
Ice roads are kept by the local authorities wherever the ice grows thick enough. The
traf

Road of Life ”

ect the basic physics: for a given ice thickness, there is a
maximum weight allowed proportional to the thickness of ice. There are two basic traf

c regulations in ice roads re fl

c

rules for ice roads: First, a minimum distance is speci ed between cars, in order to avoid