Sliding stability of prismatic blocks

A new model for rock slope stability analysis is proposed in which the distribution of normal forces on the contact planes is chosen to minimize the potential energy of the system, allowing calculation of the factor of safety against sliding. The classic wedge and plane are shown to be special cases of this more general model, which allows determination of the safety factor for any shape of prismatic contact surface. One of the practical implications of this work is that if three or more contact planes are involved the safety factor may be significantly lower than that calculated from the wedge model (which provides an upper limit on stability).