01 July 1997
(table 1-4). The mandrel is withdrawn and the shells filled with concrete. The shell, a monotube, may also
be driven without a mandrel (table 1-5). The walls of monotube piles are fluted and the pile tip is made of a
welded steel point. The walls can be reinforced and dowels welded to the top of the pile for connection with
the pile cap. Shell nominal diameters vary from 9 to 18 inches with lengths from 4 to 16 feet. Shell gauges
vary from 10 to 18 with the heavier gauges placed at the lower portions of the pile.
(2) Small Displacement. These piles displace the soil a little during driving and lead to minimal or no
ground heave. Penetration resistance is usually less during driving, thus allowing these piles to be driven
through obstructions and bedrock more easily than large displacement piles.
(a) Round Open-end Pipe (ROEP). These piles are open-end steel cylinders similar to those in
table 1-3, but without the flat or conical tip. Soil within the circular pipe can be easily taken out and the open
tube filled with concrete.
(b) Steel H-section (HP). These piles have similar to flanged or wedged steel beams and have the
ability to be driven through hard and resisting materials including some rock formations as shown in
(c) Helical Steel. These piles consist of square extension sections of galvanized steel coupled to
helical sections, table 1-7. Helical screws are spaced from 3 to 10 feet apart. They can be installed in
locations where space is limited using portable rotary equipment. Several sections are bolted together to
provide the correct length. Helical screws are useful for resisting both tension and compression loads.
Construction of the structure can begin immediately after the screw pile is installed because concrete is
often not necessary; however, concrete can be placed at the top of the pile to increase rigidity and bending
resistance. Helical screw piles are useful for supporting lightly loaded structures.
(3) Composite. Composite piles consist of sections of different materials joined together to use the
advantages of each of the materials. These piles typically consist of concrete and steel pipe or concrete and
steel HP sections (table 1-8). Concrete and timber combinations are seldom used because good joints are
difficult to construct.
(4) Sheet Piles. Sheet pile cellar structures have numerous applications, but are primarily used as
cofferdams. They may also be used as retaining walls, fixed crest dams and weirs, and walls in locks.
Straight sheet piles are used for cofferdam cells, and Z sheet piles are used for walls.
(a) A principal advantage of sheet pile structures is that they may be built in water, thus eliminating
any requirement for dewatering.
(b) The most common sheet piling material is steel, but sheet piling may also be made from
aluminum, plastic, and concrete. Steel sheet piling specifications are available from Pile Buck Inc., Attn:
Publications, P. O. Box 1056, Jupiter, FL 33468-1056.
(5) Special Piles. These piles are useful for special applications and require special construction
(a) Rotated Casing. These piles are installed by rotating heavy-gauge steel tubular casing that has
a cutting edge. Soil cuttings are removed with circulating drilling fluid. The interior of the casing may then be
filled by pumping a sand-cement grout through a tremie. The casing may be removed while the grout is
being pumped into the hole. Reinforcing steel may be placed to increase resistance to lateral and uplift
forces. These piles are useful where boulders or other obstructions are encountered.
(b) Expanded Base Compacted (Franki Piles). A steel tube is first driven to the required depth. An
enlarged base is formed by driving small charges of zero slump concrete down the tube with hammer blows
until the appropriate base is formed (table 1-9). Additional concrete charges are rammed into place against