15 August 2002
Inconsistency in Partial Passive Pressure Assumption. The earth
pressure at floor level should be no greater than active pressure, because the horizontal
displacement of sidewalls is zero at about floor level, which is the approximate center of
rotation for the sidewalls. Nevertheless, the method of approximating the total passive
resistance for the condition of dock empty, as described previously, has proved
satisfactory for existing structures so designed.
Full Hydrostatic Dock. The distribution of upward pressure beneath a
dock designed to resist full hydrostatic pressure is known when the dock is empty,
because the dock weight is nearly equal to total buoyancy.
Relieved Floors. For relieved floors, earth pressures are not uniform
because they are dependent on slab deflections induced by concentrated ship loads
and moments at the wall bases. For the solution of elastic foundation problems and
associated soil pressures, see DM-7.02 Foundations and Earth Structures.
Friction on Sides
. In addition
to the dock deadweight, friction piles, and
also is effective in preventing uplift.
5-188.8.131.52.1 Mean High Water. To determine the frictional resistance for an empty
dock at mean high water, the lateral force acting against the sidewalls (that is, the force
corresponding to the active pressure of submerged earth) is multiplied by the coefficient
of friction for the earth material on the sidewall material.
5-184.108.40.206.2 Extreme High Water. Stability against uplift at extreme high water is
computed using a deadweight of the earth wedges as described in section 5-2, instead
of frictional resistance.
LIVE LOADS. For design purposes, conditions comprising live loads are:
Shiploads applied to dock floors through blocking.
Wheel loads from crane wheels, railroad tracks, and trucks applied to
local beam and slab supports.
Local static and moving loads on roofs and floors or pumpwells.
Railroad track loadings, as a surcharge of earth pressure, from tracks
carried on ties and ballast adjacent to sidewalls of docks and walls of
An impact allowance of 15 percent is made for moving loads for
structural members forming the primary support for the moving loads.