They are defined as micropiles when the drilling diameter does not exceed 300 mm. Rotated or rotogravure in soil of any nature and consistency, they are used in containment works (Berlin), underfloor works. The armor is made up of a tubular steel (valves or not) while the injection can be gravity (using cement mortar) or pressure (cementitious cement with appropriate ratio a / c) using double shutter through the valves present In the reinforcing tube.