7
DESIGN OF ICE BOOMS
Force per unit width
Average
Average water
(kip/ft)†
Span
(kN/m)
depth
velocity
Froude
ft (m)
Designed
Measured
ft (m)
ft/sec (m/s)
number
400
0.58
1729
0.952.75
0.020.12
(122)
(8.5)
(59)
(0.290.84)
400
1.38
0.37
18
1.5
0.06**
(122)
(20.1)
(5.4)
(5.5)
(0.46)
400
0.62
0.97
18
1.5
0.06**
(122)
(9.1)
(14.1)
(5.5)
(0.46)
400
0.64
100
1
0.06
(122)
(9.3)
(31)
(0.3)
205
0.73
1031
2.7
0.090.15
(63)
(10.7)
(39)
(0.82)
avg.
0.25††
400
10
1
0.06
(122)
(3.7)
(3)
(0.3)
250
1.12
5.4
1.15
0.09
(76)
(16.3)
(1.7)
(0.35)
118
3.2
34
2.4
0.07
(36)
(47)
(10)
(0.73)
260
0.66
0.42
5
2.53
0.160.012
(79)
(2.2)
(6.1)
(1.5)
(0.760.9)
†kips = kilopounds of force
**Wind driven lake ice can override boom
††Estimated force level at time of anchor cable failure
dramatically. For booms at lake-to-river confluences, where ice
arch formation tends to occur naturally, the forces on the boom
have been assumed to derive from a 454590 triangular area
of ice upstream of the boom, the long side of the triangle aligned
with the length of the boom (Abdelnour et al. 1994). Figure 3
shows the fractured ice area that contributes to the ice loading for
a wide boom on a lake. Note that the maximum load occurs at the
central spans.
Water drag on
In rivers, the water shear on the underside of the ice cover is
ice cover
usually the primary force acting on a boom. If the drag force
beyond five river widths upstream is not felt by the boom, the
water shear force per unit river width for a wide rectangular
channel can be determined by: