Tips & News - April 2012

TIPS NEWS &

At thispoint, all four helical pileshavebeen driven intoplace.The next steps areexcava- tion, cuttingandweld- ing the I-beams.

boom digger because the operator could better control the drive motor and could install the piles at a more precise angle.

The crew also built a jig to use as a visual reference. The jig was a tripod with the legs angled at the correct drilling slopes (in two different directions). The drill operator could compare the angle of the piles he was driving to the slope of the jig. Angle was important because the helical piles had to be fairly close to the base of the tower at the top, but they had to taper away from the tower to provide lateral stability and to clear the grillage foundation below it. The operator screwed the piles down until the required torque was reached. That occurred at various depths but on average were about 20 feet down. The lead section of the helical piles was 10 feet long (including a 7-foot by 2-inch- square solid shaft with helix plates 10, 12 and 14 inches in diameter topped by a 3-foot by 8-inch-diameter pipe/box- coupler section). We then used two extensions, each 10 feet long and 8 inches in diameter.

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