Ice Thickness (m)
0 0.2 0.4 0.6 0.8 1 1.2
Mile 9
1.2
1
300 m
8.2
1
1
Mile 8
1
Boom
c. Hour 20.
Figure 14 (cont'd).
downstream boundary condition at RM 13 was a water
confluence. The water level at the boom location is
125.27 m (411 ft). Water discharge is 650 m3/s (23,000
surface elevation of 123.6 m (405.6 ft). Upstream
ft3/s), the same as in the previous case. Ice discharge is
boundary conditions were a constant water discharge
about 6.8 m3/s (240 ft3/s).
of 566 m3/s (20,000 ft3/s) and an ice discharge of 11.3
m3/s (400 ft3/s). In the second simulation, for domain 2
Since the water velocity near the boom is less than
0.6 m/s (2 ft/s), ice stops at the boom, and an ice
(RM 513), the boom was placed at RM 8.2, above the
accumulation develops upstream.
Lewis Bridge. The same water and ice discharge
The simulated ice thickness distributions at hours
conditions as in the first simulation were used. The
10, 15, and 20 are shown in Figure 14. The results show
downstream water level at RM 5 was 120.95 m (396.8
that the ice cover length is about 3.2 km (2 miles) at
ft). The goals of these simulations were to see how the
hour 20, and the thickness was in the range of 0.9 to
ice jams and boom loads would develop if the booms
1.2 m (3 to 4 ft), similar to the ICETHK-calculated ice
were 100% effective.
thickness.
The simulated results showed that the ice thickness
at the boom locations was high and that the ice
grounded across most of the channel width near the
ASSESSMENT OF ICE BOOM
boom, as shown in Figures 15 and 16. The simulated
ALTERNATIVES
jams increased upstream water levels significantly, as
The calibrated model was used to further assess the
shown in Figure 17. Upstream of the toe area, the ice
effectiveness of ice boom alternatives. Simulation
thickness decreased to about 0.9 to 1.2 m for the boom
results are presented here.
located at RM 8.2, and 0.9 to 1.8 m for the boom located
at RM 16.
100% Effective ice booms normal to
The loads on the booms are shown in Figure 18.
flow direction
The maximum load per unit width was about 40 to 50
Two simulations were carried out with a 100%
kN/m. The results showed that the boom loads leveled
effective ice boom. Limiting conditions for ice
off as the jam extended upstream. This was attributable
accumulation behind the boom were not imposed in
to the grounding of the jam, as well as the increase in
these simulations. The initial condition in the first
bank resistance as the jam progressed further upstream.
simulation for domain 1 (RM 1320), with the boom at
In domain 1, because of the low water discharge, the
RM 16, was an open water, steady-state, ice-free flow
high bed elevation causes the right one-third of the
at a discharge of 566 m3/s (20,000 ft3/s). The
channel width to have no flow.
21
Previous Page
