Non-dimensional analysis for rock slope plane failure in seismic (pseudostatic) conditions

This study examines plane failure analysis of rock slopes and discusses its effect on seismic actions in a non-dimensional form, incorporating external loads transferred by anchors and stability indicators such as the depth of tension cracks and the failure plane dip. The results of limit equilibrium analyses, in terms of attained level of safety, are summarized in stability charts which can be used for design and assessment. Following guidelines established by Eurocode EC7, the stability is assessed through the R/E ratio, i.e. the ratio of the resisting shear forces (R) acting on the sliding surface and those promoting sliding (E). The proposed stability charts can be applied to various common practical situations, in order to provide a preliminary - but quantitative - assessment of the rock slope stability. As an example of an application, the paper focuses on the stability of a rock mass located at the bottom of the southern slope of the “Sasso di Pale” mountain (Central Italy), at the outskirts of the village of Pale. As many other historical towns in Central Italy, due to their location close to rock masses, this site is particularly exposed to instability phenomena such as plane failure and rock wedge failure. The structural-geological survey allowed us to identify the main joint sets affecting the behavior of the rock mass and, accordingly, we examined the plane failure mechanism involving sliding along a single plane. Stability verifications in pseudostatic conditions have been performed by adopting the proposed charts, consistent with Eurocodes prescriptions.