| A driven pile is a relatively long,
slender column, provided to offer
support or to resist forces, made of
preformed material having a
predetermined shape and size that can be
physically inspected prior to and during
installation, which is installed by
impact hammering, vibrating or pushing
into the earth. Quality
Driven piles are a total engineering
solution. The design, installation and
quality assurance that are a part of
each driven pile combine to eliminate
guesswork and produce a known, reliable
and cost effective product that can
accommodate a wide variety of subsurface
conditions.
Driven piles consist of natural
materials or pre-manufactured structural
shapes built to precise tolerances
utilizing high strength materials and
reliable quality control. All driven
piles conform to ASTM standards. Their
quality is consistent from the first
pile to the last and can be seen and
verified prior to installation.
Driven piles maintain their shape
during installation. They do not bulge
in soft soil conditions and are
typically not susceptible to damage from
the installation of subsequent piles.
Many hollow-section piles can be
visually inspected after installation to
assure integrity. Most solid-section
piles are uniform in section and can be
dynamically inspected to verify
integrity.
The pile driving process can be
easily modeled prior to installation to
determine adequate and economic
equipment selection. Static or Dynamic
testing can confirm load carrying
capacities of installed piles. Dynamic
testing can easily confirm proper hammer
performance and its affect on the pile.
Many modern hammers have impact velocity
measurement devices permanently
installed, providing a very high level
of quality control.
Cost Effective
Driven piles are usually the most
cost effective deep foundation solution.
You pay only for what you need. There
are no hidden extra costs or added
expenses for site clean-up. The wide
variety of materials and shapes
available for driven piles can be easily
fabricated or specified for high
structural strength, allowing them to be
driven by modern hammers to increased
working loads thus requiring fewer piles
per project, resulting in substantial
savings in foundation costs.
Pile capacity is easily verified by
either static or dynamic pile testing.
Capacity per pile or pile length can be
easily optimized to provide exactly the
required capacity (including safety
factors) to minimize foundation costs.
Testing also eliminates the uncertainty
of bearing capacity estimates based on
static analysis. There is no need to be
overly conservative and thus wasteful to
protect against failure.
As an additional benefit, driven
piles often gain capacity after
installation. Shaft soil strength
usually increases with time after pile
installation is complete to provide
additional load capacity. This
phenomenon, called “setup”, can result
in substantial foundation cost savings
when considered in the design and
confirmed by testing. The incorporation
of setup into the foundation design
results in fewer piles and/or shorter
piles driven with lighter equipment. The
reduction in time, labor and materials
provide substantial cost savings to the
owner.
Adaptability
Driven piles are installed to
accommodate compression, tension or
lateral loads. Piles can be selected to
meet the specific needs of the
structure, site conditions and budget.
You can select from a variety of
materials and shapes that best meet your
needs.
Driven piles can be:
Steel
- H-Pile
- Pipe (open-end or
closed-end)
- Tapered
- Shell (mandrel
driven)
- Sheet Pile
Concrete
- Square
- Octagonal
- Cylinder
- Sheet Pile
Timber
Composite piles that combine pile
types (e.g., a concrete pile with a
steel tip extension).
Driven piles easily adapt to variable
site conditions to achieve uniform
minimum capacity with high reliability,
thus eliminating uncertainty due to site
variability. Driven piles are usually
installed to established criteria (e.g.,
minimum blow count per unit penetration,
sometimes with a minimum penetration).
Because they are normally driven to a
blow count to assure the desired minimum
capacity, pile lengths may vary when
subsurface conditions are not uniform.
Driven piles may either be cut-off to
shorten their length or spliced to
extend their length. Splice designs
usually meet or exceed the strength of
the pile itself. Pile shoes (or
“points”) can be added to assist
penetration requirements and provide
very reliable contact with rock. The
optimum length is used for each pile
which accommodates all site conditions.
Driven piles adapt well to unique
site conditions and restrictions. They
are ideally suited for marine and other
near shore applications. There are no
special casings required and there are
no delays related to the curing of
concrete. Piles driven through water can
be used immediately, allowing
construction to proceed in a timely
manner. For bridges or piers, driven
piles can be quickly incorporated into a
bent structure allowing the bridge or
pier itself to be used as the work
platform for succeeding piles in
top-down construction.
To minimize disturbance in wetlands
or allow work over water, driven piles
can be used to construct temporary
trestles. Piles installed to meet any
temporary construction need can be
extracted when the need is ended.
In earthquake prone regions, large
diameter driven piles are well suited to
resist seismic forces. Non-displacement
pile sections (e.g. H piles) can be
utilized to minimize vibration effects
on nearby existing structures. In
corrosive environments, coatings and/or
additives can be used to mitigate the
effects of corrosion thereby lengthening
the service life of a structure.
Coatings can also be used to mitigate
the effects of negative skin friction.
Reliable and Available
Pile driving contractors can be found
all over the country. The equipment and
installation methods are time-tested and
well proven. Advances in materials,
equipment, methods, and testing
continually combine to improve the
efficiency of driven piles.
Recording the blow count versus depth
during pile driving easily documents
successful pile installation. You know
what you have at the completion of
driving. Because driven piles are
usually driven to a blow count
criterion, they will have a measurable
capacity providing assurance that they
meet the project requirements. Piles can
be easily driven through upper soft soil
layers regardless of the soil type and
groundwater conditions.
Driven piles have vastly superior
structural strength. Driven piles almost
never fail structurally during static
testing or static loading. They have
high lateral and bending resistance for
their entire length making them ideal to
resist wind, berthing and seismic
loading conditions. Driven piles can
tolerate moderate eccentricity in the
application of superstructure loads due
to their full-length strength. Piles can
be driven either vertically or at
various angles of inclination to
increase support for lateral loads. In
special cases, piles can even be driven
horizontally.
Residual Benefits
Pile driving is relatively easy in
many soils. Since the soil at the toe is
in a compacted condition for
displacement piles, end bearing can
often carry a substantial load. There
are no "soft bottom" soil conditions so
large settlements for end bearing piles
are eliminated.
Driven piles displace and compact the
soil. Other deep foundation options can
require the removal of soil and
considerable subsidence, which can
undermine the support of adjacent
structures and cause excessive
deformations, both of which can result
in structural problems.
Drilling for cast-in-place piles
relieves soil pressures and reduces unit
shaft resistances. In groups of drilled
piles the removal of soil generally
loosens and weakens the soil structure,
reducing the capacity of previously
installed piles. Groups of driven
production piles densify the soil,
improving the capacity of previously
driven piles. In groups, driven
production piles usually have a higher
capacity than the test pile while
drilled production piles often have a
lower capacity than the test pile. Thus,
driven piles generally have higher
capacities than other pile types of the
same diameter and length.
Driven piles require no curing time
and can be driven in natural sequence
rather than skipping alternate piles,
thus minimizing the moving of the
equipment and speeding installation.
Environmentally Friendly
Driven pile installations usually
produce no spoils for removal and
therefore no exposure to, or costly
disposal of, potentially hazardous or
contaminated materials. The site is left
clean and ready for the next
construction activity.
Alternate Uses
The most common use of the driven
pile is in deep foundations. Driven
piles can also be utilized in other
applications such as pile-supported
embankments, sound wall barriers,
retaining walls, bulkheads, mooring
structures, anchorage structures and
cofferdams.
A DRIVEN PILE IS A TESTED
PILE |