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Ground Stability, Foundations and Substructures 107
Steel headband protects
pile
Pile hammer
Pile hammer located over
the top of the pile
Socket
Central reinforcing bar
Pile driven with hydraulic
hammer
Steel headband protects
the concrete pile
Segment lengths =1.5,3
and 4 m
Standard spigot socket
junction
General load capacity of precast concrete piles
Spigot
mm SWL
(kN)
mm SWL
(kN)
150 200 250 600
175 300 275 700
200 400 300 800
225 500 350 1200
Figure 3.42 Precast concrete pile segments (adapted from http://www.roger-bullivant
.co.uk).
conditions caused by fill, obstructions and boulders can also be dealt with. The piles are
capable of taking large axial loads. Tubular steel piles can also accommodate horizontal
loads resulting from bending moments and horizontal reaction, and can resist vertical
tension loads that are a result of uplift and heave reactions.
Normally the piles are driven with an open end so that soil fills and plugs the void; in
exceptional circumstances, the end of the pile can be closed by welding and end plate. The
void at the top of the pile is filled with concrete. Reinforcement can be positioned in the
pile, allowing it to be tied into the pile cap’s reinforcement cage. The piles are top driven
using rigs with hydraulic hammers. The site should be firm, dry and level ready to receive
the piling rigs, which can weigh up to 35 tonnes.
Driven cast-in-place piles
Driven cast-in-place piles are of two types: the first has a permanent steel or concrete casing
and the second uses a temporary casing. The purpose of driving and maintaining a permanent
casing is to consolidate the subsoil around the pile casing by the action of driving.