Effect of Three-Dimensional Configuration of a Foundation-Soil System on the Surface and Body Wave Propagation

The objective of this study is to investigate the effect of three-dimensional configuration of a foundation-soil system from the viewpoint of elastic wave propagation. The configuration considered in the study is an embedded square foundation placed on a two-dimensional slope ground subject to obliquely incident surface and body waves. Vibration direction of the incident wave is not parallel nor perpendicular to the longitudinal direction of the slope. The analysis method is a combination of three-dimensional finite element and 2.5-dimensional thin layer and finite element methods along with the substructure technique. It was found from the study that the wave field becomes very complex when there exists a foundation, causing a fairly big difference between 2.5-dimensional results (a slope ground subject to obliquely incident waves) and three-dimensional ones (a slope ground with an embedded foundation subject to obliquely incident waves). In the case of ambient vibration, the wave field is affected by a slope and the frequency dependency of H/V spectra and dispersion curves in the area close to the slope show significant fluctuation because of this. The existence of an embedded foundation also has a significant influence on the wave field. The seismic wave field, however, is less affected when compared to ambient vibration, but significant amplification is observed near the slope.