Sequential failure of granular slopes

A review of some field records showed that a two-wedge mechanism formed when failure occurred in a slope underlain by a thin weak layer. A physical model which promoted plane strain conditions was designed for the study of the sequence of failure. The model consisted of a simple granular slope resting at its angle of repose on a cohesive layer. At low confining pressures, the failure of the sand in plane strain was described by a deformational failure criterion.\ud \ud The sequence of failure of the model slope was determined from measurements of photographic records of experiments. The slope was analysed using numerical models and stability methods, with emphasis on the discontinuous nature of the material. A method based on the principle of virtual work and using an energy dissipation function for the definition of the critical failure mechanism was proposed by the author, who found its predictions concurred with the experimental observations. The use of an energy based analysis led to the replacement of the factor of safety by an energy quotient, Q. The virtual work analysis was applied to a prototype example and was found to give good agreement with field measurements