Pile Design and Construction Practice, Fifth edition

Chapter 2
Types of pile
2.1 Classification of piles
The British Standard Code of Practice for Foundations (BS 8004: 1986) places piles in three
categories. These are as follows:
Large displacement piles comprise solid-section piles or hollow-section piles with a closed
end, which are driven or jacked into the ground and thus displace the soil. All types of
driven and cast-in-place piles come into this category. Large diameter screw piles and
rotary displacement auger piles are increasingly used for piling in contaminated land and
soft soils.
Small displacement piles are also driven or jacked into the ground but have a relatively small
cross-sectional area. They include rolled steel H- or I-sections and pipe or box sections
driven with an open end such that the soil enters the hollow section. Where these pile
types plug with soil during driving they become large displacement types.
Replacement piles are formed by first removing the soil by boring using a wide range of
drilling techniques. Concrete may be placed into an unlined or lined hole, or the lining
may be withdrawn as the concrete is placed. Preformed elements of timber, concrete or
steel may be placed in drilled holes. Continuous flight auger (CFA) piles have become the
dominant type of pile in the UK for structures on land.
Eurocode 7 (EC7) (1.2) does not categorize piles, but Clause 7 applies to the design of all
types of load-bearing piles. When piles are used to reduce settlement of a raft or spread
foundation (e.g. Love (2.1) ), as opposed to supporting the full load from a structure, then
the provisions of EC7 may not apply directly. A basic classification with examples of
displacement piles is given in BS EN 12699: 2000 Execution of special geotechnical work –
Displacement piles.
Types of piles in each of the BS 8004 categories can be listed as follows:
Large displacement piles (driven types)
(1) Timber (round or square section, jointed or continuous)
(2) Precast concrete (solid or tubular section in continuous or jointed units)
(3) Prestressed concrete (solid or tubular section)
(4) Steel tube (driven with closed end)
(5) Steel box (driven with closed end)
(6) Fluted and tapered steel tube