Terms Used in Pile Foundations

Some of the terms used in pile foundations are,

Anvil: The part of a power operated hammer which receives the blow of the ram and transmits it to the pile.

Composite pile: A pile whose length is made up of more than one material, e.g., timber at bottom and concrete at top.

Dally: A cushion of hardwood or other material placed on top of the helmet to receive the blows of the hammer.

Driving Cap: A temporary cap placed on top of a pile to distribute the blow over the cross-section and to prevent the head being damaged during driving.

Drop or stroke: The distance which the weight is allowed to fall on to the head of the pile.

Drop hammer: A hammer, Ram or monkey raised by a winch and allowed to fall by gravity. A Single acting hammer is raised by steam, compressed air, or internal combustion, and allowed to fall by gravity. A double acting hammer is operated by steam, compressed air or internal combustion for lifting the ram and for accelerating the downward stroke.

Helmet: A temporary steel cap placed on top of a reinforced concrete pile to retain the packing in position and to prevent the head from being damaged during driving.

Pile bent: A number of piles projecting above the ground up to the bottom of bridge girders. The piles are connected by capping beams on which the bridge decking rests.

Ram: The rising and falling part of the hammer which delivers the blow.

Set: Is the penetration of the pile per blow during the final stages of driving.