Lateral support provided by deep foundations can be an effective means to stabilize existing and potential landslides, and deep foundations contribute to the stability of support-of-excavation systems. However, defining the structural resistance and implementing it in a slope stability analysis that satisfies LRFD requirements is a source of significant confusion and miscommunication among geotechnical and structural designers.
This report explains the implications of applying (or not) structural resistance factors at various stages of the analysis. Furthermore, three example cases are presented and analyzed probabilistically to demonstrate how reliability is influenced by the commonly available methods for factoring structural resistance in commercial slope stability software. A recommended approach for factoring and implementing deep foundation structural resistance in slope stability analyses is described along with a simple example.