DRILLING AND MICRO PILING WORKS
Micropiles, or mini piles, are foundation structural elements constructed using high strength, small-diameter, typically 6 to 12” (150 to 300 mm), steel casing, and/or threaded bar, which are encased and surrounded by grout within soil or rock. Since micro piles can be installed with relatively small drilling equipment, they are an effective support for applications with restricted access and/or low headroom. They permit facility upgrades with minimal disruption to normal operations.
Drilling is a cutting process that uses a drill bit to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multi-point. The bit is pressed against the work-piece and rotated at rates from hundreds to thousands of revolutions per minute.
TYPES OF MICRO PILING WORKS
TYPE A MICRO PILES
Type A micropiles use tremie grouting and through gravity head. The grouting is started from the bottom and follows a similar tremie grouting procedure followed in conventional piles.
TYPE B MICRO PILES
After performing the initial tremie grouting, a pressure grouting is followed simultaneously with the lifting of the casing from the bond zone. The second stage pressure grouting is done through a preinstalled tube. Second stage grouting serves in enhancing grout soil bonding.
TYPE C MICRO PILES
In these types of piles, pressure grouting is followed by tremie grouting. On completion of pressure grouting, a global injection grouting is performed through a pre-installed sleeve port pipe. This grouting shall be done before the hardening of primary tremie grout.
TYPE D MICRO PILES
This method is similar to Type C . In this method primary grout is done under pressure and after hardening secondary grout is done through installed sleeve ports. Packers are also provided for multiple injections.