damage to timber piles. Pile driving is often decided by a judgment that depends on the pile, soil condition, and driving equipment. Overdriving typically occurs when the dynamic mstresses on the pile head exceed the ultimate strength of the pile. Timber piles can broom at the pile tip or head, split, or break when overdriven. Such piles have an indefinite life when constantly submerged or where cut off below the groundwater level. Some factors that might affect the performance of timber piles are the following:
(a) Splicing of timber piles is expensive and time-consuming and should be avoided. The full bending resistance of timber pile splices may be obtained by a concrete cover (Figure 1-1a) (Pile Buck Inc. 1992).
Other transition splicers are available to connect timber with cast concrete or pipe piles.
(b) Tips of timber piles can be protected by a metal boot (Figure 1-1b).
(c) Timber piles are normally treated with creosote to prevent decay and environmental attack.
(d) American Society for Testing and Materials (ASTM) D 25 provides physical specifications of round timber piles. Refer to Federal Specifications TT-W-00571J, “Wood Preservation: Treating Practices,” for other details.
Figure 1-1. Timber pile splice and boot