Lateral Pile loads can be analyzed using a program called L-Pile. It has
been approved by several DOT's for use in designing Soldier Pile type
retaining walls, Pole overturning, etc.. The newest version is Windows
based and is much more user friendly than the older DOS versions which can
be down loaded from several DOT's and University's. The New Windows version
cost but if you need it for more than one project it's not to bad.
Robert W. Stevens, Jr., P.E.