A micropile is small-diameter deep foundation element (typically up to 300mm in diameter) that can extend to depths of 60 metres. Micropile foundations may consist of a single pile or a group of piles arranged in a grid or wall (line) pattern.
Micropiles are typically constructed with conventional drilling equipment by excavating a vertical shaft to the design depth and backfilling it with steel reinforcement and grout or concrete. A steel casing may be installed temporarily or permanently depending on project requirements.
SBC has developed an alternative and cost-effective installation micropiling solution that reduces construction timelines and spoil management requirements. Different the traditional drill-and-dispose approach, SBC’s drive-and-displace installation method generates minimal spoils by using a high-capacity drill rig equipped with a specialty displacement tool that is driven into the ground while radially displacing the soil and compacting it into the sides of the shaft. Once at the design depth, concrete or grout is pumped into the shaft through the hollow center of the tool as it is extracted from the hole. When using this method, reinforcing steel can be set into the shaft immediately after the tool is extracted.
- Micropiles are a practical foundation solution for projects with constraints that make alternative methods difficult or impossible. They can be used to overcome challenging geotechnical conditions, natural or man-made obstructions, sensitivity to adjacent structures, limited access and low headroom.
- Driven-displacement piles have a relatively high bearing capacity attributable to the soil densification that occurs during installation.
- Minimal spoils are produced when the driven-displacement method is used, reducing installation time and soil management requirements.
- The construction process produces relatively low noise and vibration levels.
Micropiles, particularly when installed using the drive-displacement method, are ideal for projects with soft or contaminated subsurface soils.