LATERAL EARTH PRESSURES BEHIND ROTATING WALLS

Classical earth pressure theories are valid strictly for retaining wal ls subject to uniform free translation. Practically all retaining wall s 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 pre dicting the lateral earth pressure at any wall displacement behind a r otating 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 prese nts a simple analysis method using a modified Coulomb's solution of ac tive pressure. The deformation pattern and the associated mobilization of shearing resistance in the soil as affected by the wall movement a re considered in a simplified manner. Comparisons of calculated result s with solutions from FEM and observations from model tests show that the method can provide a good prediction of lateral pressures for wall s rotating about the base when proper distributions of mobilized shear ing resistance and wall friction are used. For walls rotating about th e top, the prediction is fair due to arching and the difference betwee n assumed and observed rupture mechanisms.