COLD REGIONS TECHNICAL DIGEST NO. 96-1
24
Shackles
Chain
Connector Plate
Open Spelter Socket
Closed Spelter Socket
14. Standard fittings
useful in the design of
Chain connected to wire rope by
ice boom connections.
shackle and closed spelter socket
cially designed weak points, may be incorporated in the design,
permitting individual boom components to fail in a way that
prevents failure of the entire structure. For example, a fuse link at
one end of the boom cable would allow the span to open, reducing
the force on the anchor cable. In contrast, if the anchor cable is
allowed to fail first, the increased load on the adjacent anchor
cables might cause their failure as well.
Design example
This example is based on an ice boom system designed for the
Allegheny River Lock and Dam 8. Figure 15 shows a plan view of
the river area upstream of the lock and dam. An elevation of the
free overflow weir is shown in Figure 16. Average discharge
values for the site are listed in Table 4.
The boom at this location is designed to be at an angle with the
flow, providing for an ice and debris opening, which allows brash
ice from the ship track to be flushed over the weir without clog-
ging the lock entrance.
Since a boom is effective at Froude numbers less than 0.08, one
approach is to determine the depth, discharge, and average veloc-
ity at this Froude number. This can be achieved by combining the
weir and continuity equations with the definition of the Froude
number. The calculated discharge is then checked against the
observed average winter discharges listed in Table 4. Discharge
over a weir can be estimated by:
Q = CLw H 3 / 2
where C = weir discharge coefficient, which varies between 2.5
and 3.5 depending upon the type of weir (3.3 will be
used in this example)
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