Battered Auger Cast Piles

[BigEasyGeoSleuth]

Does anyone have information whether or not it would be possible to build a 1:5 battered ACP? The structural engineer requested lateral load analyses for both a vertical and a pile with the above batter...I'm not so sure it could be built. Site is in coastal Mississippi with 27 feet medium dense sand over soft clay; pile length is 75', pile diameter is 16 inches.

 

[GeoPaveTraffic]

It is possible, not as easy as vertical, but possible. Around here we seldom batter piles due to siesmic concerns, but in your area that probably is not a concern.

 

[aeoliantexan]

Some years ago I saw 14-inch by 30-foot long piles successfully installed in saturated Mo River sands at a batter of 3:12, i believe. Later we attempted 18-inch by 75-foot piles battered at 2:12 (again, I believe, going by memory) in similar soils nearby. The auger bogged down, and a crater appeared at the ground surface before we got to full depth. Obviously, sand was flowing to the auger. For the dimensions and soil conditions you describe, I would be dubious.

 

[Gimbli]

Big Easy:

I read once, from a FHWA source I think, that battered piles highly increased shear forces on pile caps as observed substructures after earthquakes that failed in punching shear. Unless this conditions are actually attended in new codes. The author stated that vertical piles may provide enough lateral capacity based on new, in that time, developed methods (as subgrade modulus and py curves) used in modern geotechnical engineering.

 

[Gimbli]

I forgot, happy new year to all of you!!!