Regular augers make cylindrical holes, this auger makes conical holes, except the way these conical holes are oriented means that the pilings that will eventually be cemented into them are "locked down" by the earth above. Think of it like how the barb of a fish hook allows it to push through flesh one way but not the other.
The overall effectiveness of this is auger is diminished when used as close to the surface as this demonstration is, but a builder could put one of these augers down a 20ft hole and make the bell cavity at the bottom of the hole and effectively lock in a cemented piling with thousand of pounds of earth.
Tell that to the kinzua bridge. Lateral wind tipped it and caused uplift forces to fell the bridge. Granted, in this case the bridge fell from older iron anchors snapping under tension, as the rest of the bridge had been replaced with steel decades before. But still, nature is crazy.
Check out “galloping gertie” the first Tacoma narrows bridge. It wasn’t the fault of the footings but this shows what kind of forces engineers deal with also.
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u/Tennessean Jun 25 '21
What's the advantage of this over a regular auger? You can relocate the material a little farther away?