Micropiles are piles installed in the ground by means of small equipment within holes having a diameter between 80 and 250 mm. Micropiles find frequent application for the reinforcement of old structures.
The micropiles are typically formed by metal tubes or profiles that are installed and cemented into the ground.
The injection may be a single stage low-pressure backfilling (sheath grout) or can be repeated over the time at higher pressures (post-injection) creating in this case a so-called injection "bulb"
Steps of installation of a micropile: Fig 1) 1. Drilling 2. Introduction of the reinforcement 3. Backfill injections (sheath) 4. Repeated injection of the "bulb", 5. Micropile completed.
Fig 2) Formation of the "bulb" by repeated injection.