Laterally loaded single piles are usually analyzed by methods derived
directly from the classical beam on elastic foundation or Winkler soil model. Soil
strength is characterized using modulus of sub-grade reaction.
Early solutions that employed Winkler’s model assumed that the modulus of
sub-grade reaction is constant with depth, or linearly varying with depth, while
in fact it varies nonlinearly with depth due to the nonlinear soil response to
loads. The characterization of soil using “p-y curves” concept; (which relates the
soil reaction and pile deflection at typical points along its length, and extracted
from field tests), is proper for representing nonlinearity in soil response, and
gives better solutions. Another method used for the solution of the problem of
laterally loaded piles is the elastic continuum method. In this method the soil is
modeled as an elastic media, such formulation poses increased difficulty when
the soil modulus varies with depth.
The Sub-grade Reaction or Winkler method of solution is used through this
study. The soil is characterized by a nonlinear springs with employing the “p-y”
model, while the pile is modeled as a two-node element.