Author(s): Razek Abdelnour; Elie Abdelnour; Etienne Robert; Jarrod Malenchak
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Abstract: Ice Booms are deployed in rivers to accelerate the formation of a stable ice cover. Typically, their purpose is to reduce the production of frazil, and to control ice and protect any downstream water intakes from blockage, or a community or cofferdam from flooding. Ice Booms are designed to resist the drag forces applied by the current and wind during the winter. During the freeze-up, the ice will start to form at the boom then it will progress upstream. However, if the driving force due to winds and currents at the boom site are too high, the newly formed ice pans will break and run over the boom pontoons and continue downstream. This process ends when the driving force slows and becomes less than the boom resistance capacity, which results in the formation of an ice cover. Unfortunately, this does not always happen. A few Ice Boom release events that occurred during the freeze up period did not allow the ice floes to pass through. In all cases, the ice load that resulted in the boom release was well beyond the design capacity of the boom to resist the ice, to the point that led to their partial or complete release. The ice loads required to submerge the boom is relatively small, which were well below the design load of the booms’span, anchor cables and anchoring system. The similarities with all the events, was that they all occurred during the early freeze-up period when the river flow was relatively high. The release events that occurred were also caused by the environmental conditions leading up to the event including: snow precipitation, strong wind, cold weather and relatively higher river flow, resulting in significant rubble ice compaction that partially blocked the river. To avoid causing an ice boom release during early freeze-up, it is important to monitor the environmental conditions during the ice formation period and ensure that the flow does not exceed the allowable limits that could cause the boom to fail. If the flow cannot be controlled, the design of the booms must consider these events and ensure that the boom will resist the forces for an appropriate design flow expected during the freeze-up period.
Year: 2016