Upper-bound limit analysis of near-fault jointed slopes stability based on the pulse-like ground motion and slope surface concave convex characteristics: a case study

Near-fault ground motion, with short-duration, high-energy and strong pulse characteristics, is more destructive than far-field ground motion and more likely to induce complex failure modes of jointed slopes. Natural slope surfaces typically exhibit irregular shapes with significant concave convex characteristics, whose specific geometry causes slope stability to vary remarkably. Therefore, the dynamic stability of near-fault jointed slopes needs further study based on the pulse-like ground motion and concave convex characteristics. This study constructs up rotation-lower translation and up translation-lower rotation models for irregular geometric slopes with n polyline segments, incorporating concave convex characteristics and failure modes. This study derives the factor of safety (Fs) and permanent displacement expressions under each failure mode, and analyzes parameter impacts (particularly pulse-like ground motion and concave convex characteristics) using real landslide data. Studies have shown that when the pulse-like ground motion is considered, the permanent displacement of the slope can be 19 times greater than that without considering it. When the concave-convex characteristics are considered, the variation in Fs can reach 16.9%. In the case of the Ganmofang landslide (China), this study’s Fs = 1.186 has a 3.025% error from numerical simulation 1.223. In the near-fault region, the peak ground acceleration (PGA) is generally greater with a_max = 0.8 g, and the permanent displacement reaches 235.32 cm. This study reveals that slopes under strong pulse-like ground motion with short-duration and high-energy characteristics, using permanent displacement for evaluation is more appropriate and reliable.