Pile Design and Construction Practice, Fifth edition

(a) (b)
Welds
Welds
Types of pile 45
Main pile
Bevelled end
Figure 2.23 Strengthening toe of steel tubular piles (a) Internal stiffening ring (b) External stiffening
ring (c) Thick plate shoe.
2.2.5 Shoes for steel piles
No shoes or other strengthening devices at the toe are needed for tubular piles driven with
open ends in easy to moderately easy driving conditions. Where open-ended piles have to
be driven through moderately resistant layers to obtain deeper penetrations, or where they
have to be driven into weak rock, the toes should be strengthened by welding-on a steel ring.
The internal ring (Figure 2.23a) may be used where it is necessary to develop the full external
frictional resistance of the pile shaft. An external ring (Figure 2.23b) is useful for reducing
the friction to enable end-bearing piles to be driven to a deep penetration, but the uplift
resistance will be permanently reduced. Hard driving through strongly resistant layers or to
seat a pile onto a rock may split or tear the ring shoe of the type shown in Figure 2.23a and b.
For hard driving it is preferable to adopt a welded-on thick plate shoe designed so that the
driving stresses are transferred to the parent pile over its full cross-sectional area
(Figure 2.23c).
A shoe of this type can be stiffened further by cruciform steel plates (Figure 2.24a).
Buckling and tearing of an external stiffening ring occurred when 610 mm OD steel tube
piles were driven into the sloping surface of strong limestone bedrock (Figure 2.24b).
Steel box piles can be similarly stiffened by plating unless they have a heavy wall
thickness such that no additional strengthening at the toe is necessary. Steel tubular or
box piles designed to be driven with closed ends can have a flat mild steel plate welded
to the toe (Figure 2.25a) when they are terminated in soils or weak rocks. The flat plate
can be stiffened by vertical plates set in a cruciform pattern. Where they are driven on to
a sloping hard rock surface, they can be provided with Oslo points as shown in
Figure 2.25b.
Steel H-piles may have to be strengthened at the toe for situations where they are to
be driven into strongly cemented soil layers, or soil containing cobbles and boulders. The
strengthening may take the form of welding-on steel angles (Figure 2.26a), or purpose-made
devices such as the ‘Pruyn Point’ manufactured in the USA by the Associated Pile and
Fitting Corporation (Figure 2.26b) or the ‘Strongshoe’ and ‘Jet shoe’ manufactured in the
UK by Dawson Construction Plant Ltd.
(c)
Weld
Shoe