LAUSR

This article presents the results of a comprehensive geotechnical centrifuge experimental program to investigate topographic effects across a series of single-sided slopes. The experimental campaign considered a range of governing factors, including slope inclination and ground-motion amplitude, frequency content, and duration. The testing program was nondestructive, allowing the centrifuge models to be subjected to over 140 different ground motions. Clear evidence of topographic effects, including amplification and deamplification of ground motion, were observed. Topography modified the frequency content and amplitude of the ground motion such that at the slope crest (1) peak ground accelerations ranged from 50% less than to 200% greater than the free-field, and (2) ground-motion mean square frequency shifted by as much as 55%. Higher topographic amplification levels lead to a larger topographic zone of influence, which, on average, spanned a distance equal to the slope height (H) behind and 2H in front of (toward slope) the slope crest. Physical modeling in the centrifuge proved to be a powerful experimental technique for generating empirical data to analyze topographic effects in a systematic and repeatable manner.