Laterally loaded piles in layered sand - PU curve 2

[TORB]

I am using API RP-2A WSD to find some PU curves to be used for the design of some laterally loaded piles. In the upper part I had to use the formulas for shallow depth, but the upper part is layered with friction angels in the upper layer (6m) of 41 degrees and then a layer of 5 m with 27 degrees. Is there a method where I can calculate PU-curves based on layered soils?

 

[jdonville]

TORB,

Are these anything like p-y curves?

If so, the p-y method allows soil layers.

I suggest you contact the geotechnical engineer of record for guidance on how to proceed, or ask them to evaluate the lateral capacity/deflection performance of your piled foundation.

Jeff

 

[TORB]

Hi Jeff

It is the same as p-y curves. It is easy to calculate the p-y curves when you are below the transition dept where the figure of rupture is a closed form around the pile but at the upper part the figure is a wedge moved to the surface and I can not find any method to calculate p-y curves for the pile-part in this area if the soil is not uniform.

Br
Torben

 

[jdonville]

The LPile Plus Technical manual lists 2 possible methods for doing this. However, it's not terribly clear where the cutoff between surface heave (wedge analogy) and deeper soil resistance is, based on the discussion in the LPile documentation.

Unless the calculated displacements are large, or the embedment of the pile is relatively shallow, I would think that it probably doesn't make a great deal of difference which approach is used.

Note that there is a missing figure in the LPile Tech. manual that may help to explain where the cutoff is for cohesive soils.

Certainly, I would hope that the software would account for the relative pile geometry and at least output a warning if the results were suspect in some way. I will have to follow up with Ensoft on that one.

Regards,

Jeff

 

[Panars]

I am not familiar with the API publication, but in addition to the p-y theory, there is also a model for lateral resistance called strain wedge. The leading authors on this theory are Mohamed Ashour and G. Norris. Their paper in the ASCE Journal of Geotechnical and Geoenvironmental Engineering, May 2000, covers the method of using strain wedge theory in layered soils.

 

[SE008]

try this:

http://www.webcivil.com/lpile3.aspx