Micropiles
In FHWA-RD-96-016 “Micropiles are small diameter drilled and grouted reinforced piles used for both structural support and in situ earth reinforcement.” Typically less than 12” in diameter, design capacities frequently exceed 100 kips. Some of our installations have been successfully tested to over 300 kips or over 150 tons. Micropiles are frequently used where a deep foundation system is required in difficult substrata conditions, or where driven piles or large diameter systems are impractical due to subsurface obstructions, or limitations presented by existing buildings at or adjacent to the project site.
Construction of Micropile involves the following steps:
Drilling, placing reinforcing steel and grouting, which bonds to the soil. The pile integrates completely with the soil.
In a single step, the piles are drilled, grouted and injected using the hollow bars as drill rods and grouting ducts along with disposable special drill bits and rotary drilling methods. These drill bits have jet openings which allows for pressure grout penetration while drilling process is carried out into the soil.
When the drill is penetrating the soil and grout injection is also simultaneously takin place through the hollow bars, the drill cuttings are continuously flushed by cement grout with the help of a flushing head.
When the drill hole is stabilizing, the ground cannot cave around the drill location which acts as an advantage. And the soil around the area is being penetrated by the grout causing it to densify.
