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Micro Piles |
Pressure Grouting |
Rock Anchors |
Permeation Grouting
Soil Nailing |
Compaction Grouting |
Micropiles |
Injection Grouting |
Chemical Grouting
Our
techniques apply when adding new structures:
especially
rock anchor,
microfine cement,
soil nailing,
micropile
installations for
foundation support.
We
specialize in
slope stabilization,
anchors,
permeation grouting,
foundation repair
and support,
grouting,
soil nails,
rock drilling,
micropile installations, and
sinkholes. We
use a
problem-solving approach geotechnical
architecture of buildings, bridges,
water plants, sewage plants, tunnels,
sinkholes,
caisson,
shoring,
underpinning,
agriculture, and
roads
construction. We
are experienced in these applications:
micro piles,
sinkhole repair,
permeation grouting, pressure
grout,
soil nails,
chemical grouting,
micropiles,
compaction grout, and
rock anchors.
Our specialties are
rock anchor,
acrylamide and
compaction grouting,
mini piles,
sinkhole repair,
micropiles,
acrylamide grouting, and
soil nailing.
We will continue to dedicate ourselves to
excellence,
including
insurance mortgage, in our performance, in our
integrity, and in our relationships with our
customers. We will carefully weigh our
decisions, actions, and results to make sure
that we remain the most trusted name in the
geotechnical contracting industry. Please
visit our website
http://www.rembco.com/.
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Driven Piles
JULY
1997
7-29
Hydraulic Hammers
A hydraulic hammer is one that incorporates the use of an external energy source to lift the
hammer to the top of its stroke. For the single acting hydraulic hammer, the actual energy
induced into the pile is developed by the free-falling piston, much the same power stroke as
a drop hammer or a single acting diesel hammer. The rated energy for the differential
acting hydraulic hammer is found by similar means as other differential acting hammers.
Some will say that a differential acting hydraulic hammer is no different than any other
differential hammer.
One particular hydraulic hammer manufacturer utilizes a ram made of composite mate-
rial. In this case the ram is made of lead wrapped in steel. The stroke is relatively short for a
single acting hammer, generally about 4 feet. The theory behind this particular hammer is
that the lead ram produces a blow with a longer impact duration. This longer impact
duration produces a compression wave which is low in amplitude and long in duration. It
is thought that this type of blow is more efficient in terms of delivering driving energy to the
tip of the pile (relative to a light weight hammer with a longer stroke).
The hydraulic hammer has a variable stroke, which is readily controlled from a control
box. With the control box the stroke can be varied, finitely (reported to be in the centimeter
range), such that the stroke can be optimized to the point of matching the dynamic spring
constant of the hammer and pile. Manufacturers have stated that the ability to vary the
stroke and frequency is what makes the difference.
The general theory behind the hammer is as follows. Every ram body, depending on
material and cross sectional area, has its own dynamic spring constant. Likewise, each pile,
based on different materials and sizes, has its own dynamic spring constant. The dynamic
spring constant is also known as the acoustic impedance. It is believed that, the closer the
dynamic spring constant is between the pile and the hammer, the higher the energy
transmission will be through the pile and the lower the internal stress will be in the pile,
since all the hammer energy goes into penetration of the pile. If the hammer impedance is
the same as the pile impedance, a pile cushion would be unnecessary and driving would be
optimized.