Pile Design and Construction Practice, Fifth edition

Types of pile 35

where the level of the bearing stratum varies; also the head of a pile which buckles during

driving can be cut down and re-trimmed for further driving. They have a good resilience and

high resistance to buckling and bending forces.

Types of steel piles include plain tubes, box-sections, box piles built up from sheet piles,

H-sections, and tapered and fluted tubes. Hollow-section piles can be driven with open ends.

If the base resistance must be eliminated when driving hollow-section piles to a deep pene-

tration, the soil within the pile can be cleaned out by grabbing, by augers, by reverse

water-circulation drilling, or by airlift (see Section 3.4.3). It is not always necessary to fill

hollow-section piles with concrete. In normal undisturbed soil conditions they should have

an adequate resistance to corrosion during the working life of a structure, and the portion of

the pile above the sea bed in marine structures or in disturbed ground can be protected by

cathodic means, supplemented by bituminous or resin coatings (see Section 10.4). Concrete

filling may be undesirable in marine structures where resilience, rather than rigidity, is

required to deal with bending and impact forces.

Where hollow-section piles are required to carry high compressive loads they may be

driven with a closed end to develop the necessary end-bearing resistance over the pile base

area. Where deep penetrations are required they may be driven with open ends and with the

interior of the pile closed by a stiffened steel plate bulkhead located at a predetermined

height above the toe. An aperture should be provided in the bulkhead for the release of water,

Precast pile cap

Class 60/75 concrete Backfill

Antiheave liner and membrane

as needed

Reinforcing bar as specified

grouted in

Precast 'Presscore' segments

Class 60/75 concrete

Grout as specified in

annulus

Precast nose cone

Grout holes in segments

Existing foundation

Pressurized grout bag

to transfer load

Figure 2.15Presscore pile (courtesy Abbey Pynford Foundation Systems Ltd).