Just bear in mind if it's frictional soil (i.e., where you can rely on a friction angle), the coefficient of passive earth pressure will be greater than determined using Rankine earth pressures. This is usually a factor of 2 or 3 (typified as phi/10).
If all you have is SPT N-values and you are in granular soils, you'd fine a correlation to friction angle and then use tan^2(45+phi/2) to get Kp. You'd then multiply Kp by Cp (phi/10) to get the ultimate passive pressure for the pile.
This is a pretty easy exercize. Now what's the lateral displacemnt under that horizontal load? That's where the body's buried. . .
f-d
¡papá gordo ain’t no madre flaca!