Pile Horizontal Soil Modulus Values

Both nonlinear P-y curves and nondimensional methods for lateral load pile design require the evaluation, measurement, or calculation of a soil horizontal modulus value. Current researchers and foundation design engineers frequently use different notations and procedures that do not make clear the transfer mechanism. This note attempts to clarify the mobilized resistance mechanisms for a laterally loaded pile by considering both side shear and front pressures. No currently popular methods attempt to quantify the contribution of side shear, but it has been shown that side shear is the major contributor to equilibrium at working loads. Any modulus value which expresses the soil reaction as an equivalent uniform pressure across the pile face (diameter) is conservative, if based solely on measured pressures alone.