Full-Scale Testing of a Structure on Improved Soil Replaced with Rubber-Gravel Mixtures

We present the results of an extensive large-scale experimental campaign on the dynamic response of rubber–gravel mixtures as an innovative seismic isolation material. In the first series of experiments, the foundation soil immediately below the prototype structure of EUROPROTEAS was replaced only with gravel to serve as benchmark tests, while in the following tests two rubber–gravel mixtures with increasing rubber content per mixture weight were used. The experimental campaign included free- and forced-vibration tests. A large number of instruments of various types (accelerometers, seismometers, shape-acceleration arrays, and laser sensors) were installed on the structure, in the foundation soil and at the adjacent soil surface in order to obtain a well-instrumented 3D set of recordings to study the response of the structure and wave propagation in soil media. In this study, we seek to investigate the isolation capability of the rubber–gravel mixtures under dynamic loading. Our primary goal is to assess the effect of the rubber content of the improved foundation soil in the stiffness and the damping of the soil-structure system.