Seismic soil response of scaled geotechnical test model on small shaking table

Abstract

This research comprises a series of shaking table tests and finite element analyses of scaled soil-foundation model to determine the dynamic interaction effects between the foundation and the underlying soil. The purpose of this work is to specify a realistic geometric scaling coefficient for test model to be used in a small-capacity shaking table. The scaling factor addressed in this study involves not only geometric similarity but also kinematic and dynamic similarity with the real system. The free-field soil response under different earthquake excitations for both real system and scaled test model was directly performed by using 2D finite element method under plane-strain conditions. The kinematic interaction of the shallow foundation slab on free-field motion was also examined. In this computational model, the behavior of the soil medium is idealized by linear elastic-perfectly plastic assumption with a yield surface according to Mohr-Coulomb failure criterion. Two different earthquake acceleration records as Chi-Chi (1999) and Loma Prieta (1989) have been carried out at the bedrock level of the soil-foundation system for this study. By comparing the results of the numerical analysis with data from the laboratory tests, the proposed geotechnical model can properly simulate the seismic response of the full-scale real system. It can be concluded that the kinematic interaction effects are negligible in the low frequencies. It should be noted that the local soil properties have considerably amplified the earthquake response of the free-field motions in comparison to the bedrock excitations.