Pile design requirement

[RareBugTX]

Hello all:

For curiosity, what soil bearing capacity do you guys use as a benchmark for the need of piles in highly cohesive soil. Geotech is preparing soil report but I was wondering how does this play out when IBC allows for footing design assuming a 1500 psf without a soil report. This is for a new two story 5000 sf sfr close to a floodplain. Thanks

Rare

 

[jayrod12]

Highly cohesive, pile, sounds like friction piles are the way to go to me depending on depth of cohesive soils.

But I'm no geotech.

As an aside, it has been discussed a few times on this board. The geotech guys have been beaten down on fees to the point where a lot of the time they default to the IBC allowable values. This is because except in rare circumstances, 1500 PSF is easily achievable with standard construction practices.

If client's were willing to pay a geotech a proper fee (like they deserve in my eyes) you would likely get significantly better design values from them. Or at least you would have more confidence in the values used and ideally more useful recommendations to improve foundation performance.

 

[Teguci]

Its a factor of settlement more than bearing capacity. If you pre-consolidate the soil and drive some of the water out of it (and long term settlement) you might be able to get away with a lightly loaded shallow foundation system.