Shear Design of Drilled Shafts at Rock Interface

[aseeng]

I am using LPile for the the lateral analysis of a drilled shaft socketed into bedrock. The pile shear curves show a peak negative shear just at and below the soil / rock interface. I searched this topic on this board and the consensus was that this load is neglected in structural design. I think the idea being that if the rock is strong enough to confine the pier then shear failure cannot occur.

Does anyone know of any publications that document this philosophy? It seems to be an elusive subject.

Thanks in advance for any responses.

 

[aseeng]

For anyone interested, I found my answer in FHWA NHI-10-016 where the recommendation is to use the average shear value over a length equal to the diameter of the pier. This will be significantly smaller than the peak shear.

 

[Lomarandil]

That's an interesting problem. Thanks for following up!

 

[KootK]

Indeed, thank you for the update.

Interestingly, the averaging method would produce a similar result to assuming that you could take the shear at a distance "d" away from the the "support". And that's quite similar to your hypothesis that a shear failure could not occur in the rock.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.