Influence of base-rock characteristics on ground response

Abstract

The response characteristics of nine typical soil deposits over different types of base rock are studied in order to evaluate the influence of the base-rock characteristics on the surface accelerations. The study shows that the spectra for the surface accelerations are virtually independent of the properties of the base rock provided the latter is homogeneous. However, layering of the base rock may influence the surface acceleration spectra to an appreciable extent and certain types of analytical procedures may give grossly erroneous results for such cases.