Experimental dispersion curves of non-penetrable soils from direct dynamic measurements using the seismic dilatometer (SDMT)

Abstract

This paper presents the results of an experimental campaign in Macerata (Italy). In the first step, the research addresses the site characterization by presenting the in situ and laboratory examinations results. In a second step, the study focuses on the more in-depth interpretation of the raw signals acquired by the SDMT in the 100 m deep borehole. The cross-correlation between SDMT signals represents the standard method to estimate the velocity of the shear waves. The authors attempted to assess any dependency of the shear wave velocity on the wavenumber by applying a moving bandpass filtering to the signals acquired in the 100 m deep borehole. In seismic engineering practice, the standard mechanical models of soils are representative of non-dispersive media. This assumption originates from the scarcity of experimental investigations on the dispersion laws of soils and the confidence in dispersion's possibly negligible effect. However, a purely non-dispersive medium does not exist, and all media do show some dispersion features: the phase velocity of shear waves may depend on the wavenumber.