Engineered and Tested High Capacity Foundation Solutions

Posted by CHANCE Foundation Solutions on Mar 13, 2020 8:54:58 AM

Drivecast-LP_background-2bIn response to a demand for predictable high capacity foundation solutions, a fully grouted screw displacement pile was developed by CHANCE® engineers. Comprised of a centralized steel shaft and a patented displacement assemblies, the pile, known as the Drivecast™ screw displacement pile, is designed to create a cylindrical annulus around the central shaft that is continuously filled with grout from a  gravity-fed reservoir at the surface.

Drivecast Piles are installed to a pre-determined depth based on the required axial resistance and the allowable torque rating of the central shaft.  Axial resistance is based on end-bearing of the pile tip and side resistance due to skin friction.

The CHANCE® Drivecast screw displacement pile underwent three installations in the northeast, each achieving significantly positive test results.

Norwalk, Connecticut Installation

In Norwalk, Connecticut, the construction site had a soil profile with medium-dense sand and gravel fill over medium-dense sand, silt and gravel.

To install the screw displacement piles, the installer used an RS3500 central shaft with a diameter of 3.5". There was a displacement assembly diameter of 10/14" every 5'-0 with single lateral displacement plates. The grout shaft diameter was 12"; grouted shaft length was 25.3', and the overall pile length was 26.3' with an effective installation torque of 13,000 ft.-lbs, which matched the torque rating of the RS3500 shaft.

After completing the installation, the load test data reported a maximum test load of 200 kip, a load at deflection ≤ 1/2" at 180 kip and load at deflection ≤ 1" at 200 kip. The ultimate capacity based on 10% helix diameter net settlement was estimated to be 300 kip.

Cambridge, Massachusetts Installation

In Cambridge, Massachusetts, the construction site had a soil profile with organic fill over loose to very-dense alluvial sand deposit.

For the screw displacement pile installation, the installer used an RS3500 central shaft with a diameter of 3.5". There was a displacement assembly diameter of 10/14" every 5'-0 with single lateral displacement plates. The grout shaft diameter was 6.7"; the grouted shaft length was 20.2', and the overall pile length was 21.1' with an effective installation torque of 8,400 ft.-lbs.

After completing the installation, the load test data reported a maximum test load of 125 kip, a load at deflection ≤ 1/2" at 52 kip and load at deflection ≤ 1" at 80 kip. The ultimate capacity based on 10% helix diameter net settlement was 96 kip.

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Queens, New York Installation

In Queens, New York, the construction site had a soil profile peat overlying soft gray silty clay trending to well-graded sand and gravel till with increasing density with depth.

For the screw displacement pile installation, the installer used an RS4500 central shaft with a diameter of 4.5". There was a displacement assembly diameter of 10/14" every 5'-0 with double stacked displacement plates. The grout shaft diameter was 8"; the grouted shaft length was 13', and the overall pile length was 14' with an effective installation torque of 16,000 ft.-lbs.

After completing the installation, the load test data reported a maximum test load of 135 kip. The ultimate capacity based on 10% helix diameter net settlement was estimated to be 200 kip.


drivecast-video

These results show that CHANCE Drivecast Piles are an economical deep foundation option for design loads up to 150 kip due to 

their ability to mobilize both end-bearing and side resistance with a relatively short overall length.  Contractors can install Drivecast Piles using their existing helical pile installation equipment & crews, which help keeps costs down, while providing a higher capacity pile.   

 

Topics: Construction, Foundations, Engineering, Torque

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