Apply normal safety precautions to hand power
tools used to prepare piles for driving and in cutting off,
straightening, and aligning piles after they are driven.
Wearing safety shoes is required. Be sure you and
all your crew are wearing hard hats. Mill scale may fly
from a steel pile while it is being driven.
During the first few feet of driving a pile, keep
personnel out of the way as much as possible so that if
the tip of the pile were to strike an obstacle and slide out
of line, no one would be struck by the pile.
During actual pile driving, protect your ears. When
working over water, wear life jacket and make sure crew
members do likewise. Use safety belts as required.
Characteristics of Different Piles
As a Builder, you will be most concerned with
timber piles. Steel piling ranks next in importance,
especially where the construction must accommodate
heavy loads or the foundation is expected to be used
over a long period of time. Steel is best suited for use
as bearing piles where piles must be driven under the
Piles are longer than 80 feet.
Column strength exceeds the compressive
strength of timber.
To reach bedrock for maximum bearing surface
through overlying layers of partially
To penetrate layers of coarse gravel or soft rock,
such as coral.
To attain greater depth of penetration for
Concrete and composite piles are seldom used
because they require material and equipment that is not
normally available through military supply channels.
They are likely to be used in cases where local materials
are readily available, whereas standard military piling
would have to be received in large quantities from
CONUS. Interlocking steel sheetpiling is often used in
military construction, but concrete-steel piling can be
manufactured in the field when local material is
Precautions during Pile Driving
Be careful during driving to avoid damage to the
pile, the hammer, or both. If the pile driver shifts
position during driving, the blows of the hammer will
be out of line with the axis of the pile and both the pile
and the hammer may be damaged.
Watch the piles carefully for any sign of a split or
break below ground. When you are driving pile and it
suddenly becomes easier to drive or the pile suddenly
changes direction, a break or split has probably
occurred. When this happens, pull the pile as soon as
possible, because further driving is useless.
SPRINGING means that the pile vibrates too
much laterally. Springing may occur when a pile is
crooked, when the butt has not been squared off
properly, or when the pile is not in line with the fall of
the hammer. In all pile driving, make sure the fall of the
hammer is in line with the pile axis; otherwise, the head
of the pile and the hammer may be damaged severely
and much of the energy of the hammer blow lost.
Excessive BOUNCING may come from a hammer
that is too light. However, it usually occurs when the
butt of the pile has been crushed or broomed, when the
pile has met an obstruction, or when it has penetrated to
a solid footing. When a double-acting hammer is being
used, bouncing may result from too much steam or air
pressure. With a closed-end diesel hammer, if the
hammer lifts on the upstroke of the ram piston, the
throttle setting is probably too high. Back off on the
throttle and control just enough to avoid this lifting. If
the butt of the timber pile has been crushed or broomed
more than an inch or so, cut it back to sound wood before
you drive it any more.
When a pile has reached a level where 6 blows of a
drop hammer, 20 blows of a steam or air hammer, or 10
blows of a-diesel hammer per inch will not drive it more
than an average of one-eight inch per blow, the pile has
either hit an obstruction or has been driven to
REFUSAL. In either case, further driving is likely to
break or split the pile. If the lack of penetration seems
to be caused by an obstruction, try 10 or 15 blows of less
than maximum force; they may cause the pile to displace
or penetrate the obstruction. For obstructions which
cannot be disposed of in this manner, it is often
necessary to PULL (extract) the pile (see next section)
and blast out the obstruction with an explosive lowered
to the bottom of the hole.