Some Limits in the Use of the MASW Technique in Soils with Inclined Layers

The surface wave method is a characterization technique that allows obtaining the shear wave velocity profiles trough the measurement of the dispersion of surface waves coupled with an inversion procedure. Spectral and Multichannel Analysis of Surface Wave techniques are becoming, recently, a common investigation tool for site characterization. Homogeneous or horizontally layered soil models are assumed for the inversion of the surface wave dispersion curve and this hypothesis could represent a limitation on the practical use of the technique. In this paper, the numerical dispersion curves of a subsoil, constituted by two layers of elastic material separated by a horizontal or an inclined interface, are simulated by a finite element commercial code. This allows detecting some limits in the conventional interpretation of the surface wave tests. MASW experiments executed in two different sites in Molise Region (Italy), characterized by simple or complex stratigraphic conditions, are shown as examples to validate the assumption and the analyses made in the paper.