Micropiles

Micropiles are structural reinforced elements of diameter smaller than 300 mm. The main advantages are their high bearing capacity compared to the borehole diameter, and the capability to overpass obstacles or pre-existing foundations.
Micropiles can be used as single load bearing elements, or in groups. In this case, micropiles can be used to form retaining structures (berlin-walls, for example). 
Micropiles can be installed by using self-drilling pipes, or in a pre-formed hole. Among the drilling techniques, the most used are rotary and roto-percussion, with or without the aid of casing. Other suitable methods for installation of micropiles are
auger and coring.

The most frequent applications for micropiles are:

Foundation for new structures
Seismic retrofitting
Underpinning of existing foundation
Repair / Replacement of existing foundations
Upgrading of foundation capacity
Retaining walls
Soil improvement and strengthening