Experimental Analysis of the Effects of a Polyurethane Foam on Geotechnical Seismic Isolation

A new experimental apparatus for performing impact tests is presented, to analyse the wave propagation phenomenon in pure sand and in composite sand-polyurethane specimens, with the final aim to explore the seismic mitigation given by a polyurethane inserted into a real soil under existing structures. Polyurethane layers at three different thicknesses are considered. Experimental results show that composite specimens provide acceleration reductions increasing with the increase of polyurethane thickness. Result interpretation in the light of the elastic wave propagation theory is presented, pointing out the experimental set-up limitations, mainly due to the lack of sufficient specimen confinement.