Investigation of Foundation Vibrations Resting on a Layered Soil System

This paper presents an investigation of the dynamic response of foundations resting on a layered soil underlain by a rigid layer. Model block vibration test results are used for the investigation. For the analysis, two different methods, namely, the equivalent spring-massdashpot model and the cone model, are used. A simple method to estimate the equivalent stiffness of the foundations resting on any multilayered soil system is presented. Obtaining stiffness from the proposed method and using different values of the damping factor ranging between 1.5 and 10.0%, the dynamic response of a foundation resting on a layered soil system is computed. One-dimensional wave propagation in an elastic cone for the analysis of foundations resting on the elastic homogeneous half-space or layered soil is also used to compute dynamic responses of the foundations resting on different layered soil. Finally, results obtained from two analytical methods are compared with the test results. It has been observed from the comparison that the results obtained by the equivalent spring-mass-dashpot model with a damping factor of 1.5% matched well with the experimental results for all cases. Results obtained by the cone model match well with experimental results for the cases where the top layer is softer than the bottom layer.