Pile Design and Construction Practice, Fifth edition

80 Piling equipment and methods
356×368
(14" ×14½")UB
Gate positions
152 × 76 (6" × 3")UC
1676 1676
5258 1524
(5'-6") (5'-6") (17'-3") (5'-0")
Figure 3.8 Trestle guides for multiple vertical piles.
Top gate
Bottom gate
Three rows of five 356 � 368 mm H-piles were pitched into the guides and were driven by
a Delmag D22 hammer.
Guides can be used in conjunction with piling frames for a two-stage driving operation,
which may be required if the piles are too long to be accommodated by the available height
of frame. Guides are used for the first stage of driving, the piles carrying the hammer which
is placed and held by a crane. At this stage the pile is driven to a penetration that brings the
head to the level from which it can be driven by the hammer suspended in the piling frame.
The latter completes the second stage of driving to the final penetration (Figure 3.9).
3.1.4 Piling hammers
The simplest form of piling hammer is the drop hammer, which is guided by lugs or jaws
sliding in the leaders and actuated by the lifting rope. The drop hammer consists of a solid
mass or assemblies of forged steel, the total mass ranging from 1 to 5 tonne. The striking
speed is slower than in the case of single- or double-acting hammers, and when drop hammers
are used to drive concrete piles there is a risk of damage to the pile if an excessively
high drop of the hammer is adopted when the driving becomes difficult. There has been a
revival of interest in the simple drop hammer because of its facility to be operated inside a
sound-proofed box, so complying with noise abatement regulations (see Section 3.1.7).
2286 2565
(7'-6") (8'-5")