Traditional foundation methods can be tricky to implement when access is limited, overhead clearance is especially low, or soil conditions call for strict weight limitations. For instance, on swampy ground or low-quality soil, the machines needed to install conventional foundations cannot always operate safely or maneuver effectively.
To counter these site conditions, Hubbell Power Systems, Inc. manufactures CHANCE® Drivecast™ screw displacement piles. This product provides contractors a cost-effective solution that does not require exceptionally heavy equipment to install. It makes the Drivecast piles ideal for even the toughest conditions.
Drivecast piles use sections — or shafts — made from structural steel and have displacement modules at regular intervals. The modules utilize an innovative soil displacement methodology that helps eliminate vibrations and minimize site disturbance. Each section is rotated into the soil with the help of a hydraulic drive-head.
A gravity-fed reservoir containing high-quality grout (typically a 4,500 pounds-per-square-inch mix) is secured at the surface. As each section of the pile advances, the reservoir immediately allows the grout to be pulled into a cylindrical void until it reaches the desired column length.
Screw displacement piles are installed using agile, lightweight equipment, and the appropriate depth requirements are met by coupling sections together. Installing shorter length sections rather than full length piles with small, light-weight equipment allows for faster, safer and less invasive construction. This is particularly beneficial in difficult site conditions such as a sewer located in the middle of a busy city street.
Compared with caissons, driven piles, rammed aggregate piers and continuous flight auger piles, Drivecast screw displacement piles can be installed in much tighter spaces with limited vibrations and noise. They also can effectively pass obstructions in soil, including boulders and rubble, via pre-drilling as required. Drivecast piles can support a capacity up to 280 kip allowable load through the ability to extend the piles in sections.
The New York City Department of Design and Construction has already approved the screw displacement piles as substitutes for CFA piles for certain projects. As the popularity of screw displacement piles grows, contractors rely on Drivecast for safe, effective and efficient foundation solutions.