Identification of Soil Properties from Foundation Impedance Functions

Abstract

The possibility of using experimentally determined foundation impedance functions (dynamic stiffness) to infer the dynamic properties of the underlying soil deposit is explored. The foundation is modeled as a rigid block resting on a layered viscoelastic half‐space consisting of several parallel layers overlying a half‐space. The shear‐wave velocities and material damping ratios in the layers are determined by minimizing the difference between the experimental impedance functions obtained from forced vibration tests of the foundation and theoretical impedance funtions obtained by an integral equation technqiue. The effects that the number and range of the selected frequencies used in the analysis have on the accuracy of the identification process are studied in detail. The effects of using an incomplete set of impedance functions as well as those resulting from random errors in the data are also investigated. Finally, the use of a variability penalty to minimize the variation of inferred properties from layer to layer is considered.