What is an end-bearing pile?
An end-bearing pile, also called a point-bearing pile, is driven down to a firm, load-bearing layer and carries its load mainly through the resistance at its toe. In Dutch the pile is said to stand “op stuit”: it has reached the correct depth and the required point resistance. Driving until the pile will go no further is known as driving to refusal.
The opposite is the friction pile, which gets its capacity from shaft friction along its length. In practice most piles rely on both. Across much of the western Netherlands, where soft clay and peat lie near the surface, piles are driven into the underlying Pleistocene sand. How deep that sand lies varies a great deal from place to place.
Application
- Get site investigation data. A cone penetration test (CPT) records cone resistance with depth and shows where the bearing layer starts. Most projects need their own tests on the plot.
- Let the structural engineer set the toe level. Pile type and depth are calculated from the test results, not estimated.
- Check the pile driving record. For each pile the contractor logs depth and blows per set of penetration. This shows whether every pile has reached the bearing layer. Keep the record with your building file.
- Allow for negative skin friction. If soft layers around the pile settle, for example after raising ground levels or a falling water table, they drag the pile down instead of supporting it. The pile design must account for this downdrag.
- Think about neighbours. Driving causes vibration. Next to old terraced houses, a low-vibration pile system may be the better choice.
Common mistake: assuming that a pile which has stopped moving is automatically good. It may have hit an intermediate layer or an obstruction above the design bearing layer. Always compare the driving record with the specified toe level.
Related terms
- Shaft friction
- Cone penetration test
- Driven pile
- Bearing capacity of a pile
- Pile driving record
Want to know more about building terms? Visit our knowledge base at fredsdiyplans.com.