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...
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...