An improved displacement-based approach for seismic analysis of pile-stabilized slopes taking into account soil-structure interaction

Assessing the performance of slope stabilizing piles against seismic events is a key issue for risk mitigation purposes, with reference not only to the global collapse of the slope, but mainly to the control of co-seismic slope displacements. Either simplified pseudo-static or pseudodynamic approaches (e.g. Newmark-type) are usually employed, based on strong simplifying hypotheses regarding the mechanical interaction between piles and the unstable soil mass. This paper aims at improving traditional methods by introducing the concept of “characteristic curve” relating the value of the stabilizing force mobilized between pile and unstable soil to the relative soil-pile displacement. This will lead to a safe and consistent assessment of the permanent slope displacement associated with a given seismic event, explicitly accounting even for pile geometry (i.e. diameter, length and spacing), mechanical behavior and structural constraints (e.g. deep ground anchors), and allowing the designer to rapidly and meaningfully compare alternative design solutions