Seismic Performance of Rock Slopes and Wedges Accounting for Progressive Strength Reduction of Joints

Seismic performance of slopes is typically assessed by adopting permanent displacements as significant engineering demand parameter which can be calculated with more or less refined procedures obtained removing one or more hypotheses of the well-known Newmark rigid block model. In this study we propose a numerical procedure which allows to remove the hypothesis of constant resistance along the sliding surface introducing the progressive material strength reduction (from peak to ultimate values) induced by shear displacements along the sliding interface. The proposed procedure is implemented in a computer code for two simple but instructive geometrical problems, such as the one–dimensional rock slope characterized by the presence of one planar joint and the two-dimensional problem of a rock wedge bounded by two planar joints. The implemented code was then used to carry out a parametric analysis aimed at quantifying the effects of the progressive strength reduction on the magnitude of permanent displacements induced by a selection of accelerometric records. The preliminary results of this analysis are presented and discussed.