Pole footing embedment in soil

[nrguades]

Hi All,

I'm designing a small garage addition with concrete retaining walls supported by piles. I'm using Enercalc V6 to calculate the pole embedment depth considering wall active soil pressure and soil passive resistance per soil report. The soil report clearly stated that the piles may be assumed fixed at 3 ft into weathered bedrock below the garage subgrade. Can I use a surface restraint option at this point (3 ft below garage subgrade) where the soil report stated to be fixed? Or I will just conservatively choose, no surface restraint option since the surface restraint generated force should be resisted by some laterally supported structural members like the slab or grade beams that are connected to the piles

Thanks,
Noel

 

[csd72]

This problem would be simpler without a computer.

One thing I would note though is that you need to consider the sequence of the works. Will the retaining wall be loaded before the ground slab is poured?

 

[nrguades]

Hi Csd72,

Thanks for your reply, the retaining wall will be loaded first considering that this is a hillside construction and the piles is used as shoring as well as permanent support. But do you think, the fixed point as pointed out by the soil reports are restraint by the weathered bedrock itself and not by any other structural members?

 

[csd72]

Yes I would think that best to use only the weathered bedrock as support.

You then just need to check the stress at the interface between the concrete and the bedrock.

 

[msquared48]

How wethered is the bedrock and will it resist the lateral loads without further degredation?

How much overburden is over the bedrock, if any, and I am not talking fill for the garage slab here...

A sketch of what you intend to do here would help...

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask