Lateral earth pressures behind rotating walls

Classical earth pressure theories are valid strictly for retaining walls subject to uniform free translation. Practically all retaining walls rotate, and movements of the wall could be restricted, particularly under working conditions. The lateral earth pressure on the wall often deviates from the fully active Coulomb value. There is a need for predicting the lateral earth pressure at any wall displacement behind a rotating wall. The finite element method (FEM) is capable of providing valid solutions of lateral pressures for different wall movements, but a simple alternative method has its practical value. This paper presents a simple analysis method using a modified Coulomb's solution of active pressure. The deformation pattern and the associated mobilization of shearing resistance in the soil as affected by the wall movement are considered in a simplified manner. Comparisons of calculated results with solutions from FEM and observations from model tests show that the method can provide a good prediction of lateral pressures for walls rotating about the base when proper distributions of mobilized shearing resistance and wall friction are used. For walls rotating about the top, the prediction is fair due to arching and the difference between assumed and observed rupture mechanisms.