Governing Equations:

$$ S = \frac{P}{d \cdot E_s} I_1 R_K R_b R_v $$

where P is the applied load, d the pile diameter, E_s the average soil modulus along the pile shaft, I₁ the influence factor for a rigid pile in a semi-infinite mass and R_K, R_b, R_v are the correction factors for the effect of pile compressibility, bearing stratum stiffness and Poisson’s ratio respectively

Useful charts

Figure 1 - Plot of influence factor for a rigid pile in a semi-infinite mass, I₁

Figure 2 - Plot of correction factor for the effect of pile compressibility, R_K

Figure 3 - Plot of correction factor for the bearing stratum stiffness, R_b

Figure 4 - Plot of correction factor for Poisson’s ratio, R_v

References: Mayne and Poulos (1980)