Analysis of Impact and Traffic-Induced Vibrations for the Characterization of a Clayey Soil

The evaluation of the dynamic parameters of soils and particularly of the initial value of the shear modulus Go represent an important step in order to understand soil behaviour in the fieÌd of little deformation and to formulate proper constitutive laws able to model such behaviour. This paper describes an experimental application of the Spectral Analysis of Surlace Waves method to determine the initial value olthe shear modulus at different depths for a clayey soil. Traffic and impact generated Rayleìgh waves have been recorded using several accelerometers placed on the soil suface at various distances from the vibration source. The random nature of the source was not relevant to the analysis performed so the wave arrival at the first accelerometer, the nearest to the source, has been considered as tbe excitation input. The recorded data have been processed to obtain shear wave velocities and Go profiles. The characteristics of the soil were previousiy investigated and results of cross-hole and down-hole tests performed in the same site were available. So it has been possible to compare the results obtained in the present research employing the SASW method with those obtained using different techniques. The comparison showed a reasonable agreement in the value of Go for both impact and traffc induced vibrations though a certain scatter in results was observed.