Figure 8-27.Wire-rope sling used with 5,000-pound
airstream hammer to pull piles.
blows from a HEADACHE BALL (heavy steel ball,
swung on a crane whip to demolish walls) or a few light
blows on the butt or head with a driving hammer are
given to break the skin friction. The crane pull is then
increased to maximum capacity. If the pile still will not
start, it maybe loosened by jetting or the lift of the crane
may be supplemented by the use of hydraulic jacks.
The 5,000-pound double-acting hammer may be
used in an inverted position to pull piles. The hammer
is turned over, and a wire-rope sling is passed over it
and attached to the pile (fig. 8-27). The hammer whip
is heaved taut, and the upward blows of the hammer ram
on the sling plus the pull of the hammer whip are usually
enough to pull the pile.
TIDAL LIFT is used often to pull piles driven in
tidewater. Slings on the piles are attached to barges or
pontoons at low tide; the rising tide pulls the piles as it
lifts the barges or pontoons. To avoid the danger of
tipping barges over, place a barge on each side of the
pile with the lifting force transmitted by girders
extending across the full width of both barges.
PLANNING AND ESTIMATING
So far, you have a thorough understanding of the
materials used, and the principles of, and the
capabilities of driving pile. Preparing estimates, such
as man-days, and equipment, are usually left up to the
Equipment Operators (EOs), but should not present any
real problem for you.
Manpower estimates (fig. 8-28) for bearing piles are
based on a typical crew consisting of the following
One crew leader.
One crane operator.
Figure 8-28.Table from P-405.