Small-strain stiffness and damping ratio of Pisa clay from surface wave tests

Small-strain stiffness and damping ratio are important parameters for modelling the dynamic behaviour of soils. In particular, the experimental evaluation of the damping ratio is problematic, especially for hard-to-sample soils. Surface wave tests have proven to be a reliable tool for the in-situ determination of soil stiffness at very small strains. Recently, the simultaneous determination of stiffness and damping ratio has been developed. The technique is based on the measurement and inversion of dispersion and attenuation curves of Rayleigh waves. In this paper a novel transfer function procedure is presented. The application to data collected at the Leaning Tower of Pisa testing site, where many results from previous in-situ and laboratory test are available for comparison, is reported.