To reinforce an existing structure that is subsiding or to erect a new building, deep foundations are required.
This consists of adding an element to the land that will essentially work on side friction to reinforce its load-bearing capacity. Piles, barettes, inserts or micropiles are then installed.
Deep foundations are also used to reinforce a retaining wall (temporarily or permanently) with tie beams. This system uses a tie bar or tie cable, sealed in the ground in a boring, which is tensioned against the wall being retained.