1. Classification of deep foundations

Deep foundations include piles, bars, shafts and micropiles. Their slenderness D/B (ratio between their form D and their diameter or width B) is generally greater than 5.

Traditionally, deep foundations are classified as follows:

• the nature of the constituent material: wood, metal, concrete ;

• the method of installation in the ground :

  • bored piles and other in-situ foundations made by concreting into a borehole, with or without a metal tube for some piles,

  • driven piles, shaped in advance and usually driven into place.

When assessing load-bearing capacity, in particular, it is more important to consider the type of stress imposed on the soil by the foundation installation....