Pile Design and Construction Practice, Fifth edition

12 Types of pile
Considering the first factor, some form of displacement pile is the first choice for a
marine structure. A solid precast or prestressed concrete pile can be used in fairly shallow
water, but in deep water a solid pile becomes too heavy to handle and either a steel tubular
pile or a tubular precast concrete pile is used. Steel tubular piles are preferred to H-sections
for exposed marine conditions because of the smaller drag forces from waves and currents.
Large-diameter steel tubes are also an economical solution to the problem of dealing with
impact forces from waves and berthing ships. Timber piles are used for temporary works in
fairly shallow water. Bored and cast-in-place piles would not be considered for any marine
or river structure unless used in a composite form of construction, say as a means of extending
the penetration depth of a tubular pile driven through water and soft soil to a firm stratum.
Piling for a structure on land is open to a wide choice in any of the three categories. Bored
and cast-in-place piles are the cheapest type where unlined or only partly lined holes can be
drilled by rotary auger. These piles can be drilled in very large diameters and provided with
enlarged or grout-injected bases, and thus are suitable to withstand high working loads.
Augered piles are also suitable where it is desired to avoid ground heave, noise and vibration,
i.e. for piling in urban areas, particularly where stringent noise regulations are
enforced. Driven and cast-in-place piles are economical for land structures where light or
moderate loads are to be carried, but the ground heave, noise and vibration associated with
these types may make them unsuitable for some environments.
Timber piles are suitable for light to moderate loadings in countries where timber is easily
obtainable. Steel or precast concrete-driven piles are not as economical as driven or bored
and cast-in-place piles for land structures. Jacked-down steel tubes or concrete units are
used for underpinning work.
For the design of foundations in seismic situations reference can be made to criteria in
Eurocode 8 ENV 1998-5: 1994 Design of structures for earthquake resistance Part 5:
Foundations, retaining walls and geotechnical aspects (EC8-5); these rules complement the
information on soil–structure interaction given in EC7. The paper by Raison (2.2) refers to the
checks required under EC8-1 for piles susceptible to liquefaction at a site in Barrow.
The second factor, ground conditions, influences both the material forming the pile and
the method of installation. Firm to stiff fine-grained soils (silts and clays) favour the augered
bored pile, but augering without support of the borehole by a bentonite slurry cannot be
performed in very soft clays or in loose or water-bearing granular soils, for which driven
or driven and cast-in-place piles would be suitable. Piles with enlarged bases formed by
auger drilling can be installed only in firm to stiff or hard fine-grained soils or in weak
rocks. Driven and driven and cast-in-place piles can neither be used in ground containing boulders
or other massive obstructions, nor can they be used in soils subject to ground heave, in
situations where this phenomenon must be prevented.
Driven and cast-in-place piles which employ a withdrawable tube cannot be used for very
deep penetrations because of the limitations of jointing and pulling out of the driving tube.
For such conditions a driven pile would be suitable. For hard driving conditions, for
example, boulder clays or gravely soils, a thick-walled steel tubular pile or a steel H-section
can withstand heavier driving than a precast concrete pile of solid or tubular section.
Some form of drilled pile, such as a drilled-in steel tube, would be used for piles taken
down into a rock for the purpose of mobilizing resistance to uplift or lateral loads.
When piling in contaminated land using boring techniques, the disposal of arisings to
licensed tips and measures to avoid the release of aerosols are factors limiting the type of
pile which can be considered and can add significantly to the costs. Precautions may also be