15 August 2002
Deflection Test. Deflections at various points of a caisson under full load
(high tide with a graving dock empty) must be determined in comparison with no-load
positions, and then checked against original design data. For a convenient reference
line, use a wire stretched along the caisson centerline and fastened at the caisson ends.
Inclination Test. Inclination tests are used to determine the stability of a
caisson under light conditions. The tests are on a caisson equipped and ready for
operation, by moving known weights off center and recording the resulting caisson
inclination angles. Angles are indicated by plumb bob pendulums, and obtained at light
drafts only. Occasionally, a change in the amount of permanent ballast may be
necessary because of such tests.
SUPPORTING FACILITIES AND ACCESSORIES
Crane Rails. Provide complete crane foundations, anchor bolts, and rails
for portal cranes. Rails must be factory bent to required curvatures. Thermit weld or
weld rail joints in accordance with alternate methods subject to NAVFAC approval.
Refer to typical installation details in MIL-HDBK-1025/1 Piers and Wharves.
Cranes. Drydock cranes are usually obtained by separate contracts with
firms specializing in this type of equipment. Because of size, cranes are assembled at
sites by manufacturers, from prefabricated sections. Performance tests are required
Railroad Tracks. Installation of ballasted dockside railroad tracks should
follow standard railroad construction practice. Other railroad tracks are supported by a
dock wall or special foundations, such as piles.
Bollards and Bitts. An important construction problem in the installation
of accessory anchorages is that of correct positioning of anchor bolts during concrete
placements. Since changing positions of embedded bolts after the concrete has set
causes difficulties and expense, and is undesirable structurally, every possible
precaution should be taken against disturbing such bolts during pours. Accessories
subject to corrosion shall have basic corrosion resistant shop coats of paint after
manufacture, with finish coats on installation prior to acceptance.
Bollards and Cleats. Space bollards and cleats to suit classes of vessels
using the docks. Bollard foundations consist of large blocks of solid concrete, which
generally rest on piles or are anchored directly to dock structures or crane track
foundations. Embed anchor bolts in the concrete. Set bollard castings by crane on
layers of mortar placed on the concrete foundations.
Ladders. Use ladders of light construction, and securely anchor ladders
to masonry walls.
Manhole Steps. Manhole steps may be built into either concrete or brick
masonry. If the spacing and stagger pattern of steps is constant, it is usually
economical to fabricate special stepholding forms as reusable standard wall panels.