부산대학교 도서관

The estimate of the velocity of shear waves ( V s ) is essential in seismic engineering to characterize the dynamic response of soils. There are various direct methods to estimate the V s . The authors report the results of site characterization in Macerata (Italy), where they measured the V s using the seismic dilatometer in a 100 m deep borehole. The standard V s estimation originates from the cross-correlation between the signals acquired by two geophones at increasing depths. This paper focuses on the estimate of the dependence of V s on the wavenumber. The dispersion curves reveal an unexpected hyperbolic dispersion curve typical of Lamb waves. Interestingly, the contribution of Lamb waves may be notable up to 100 m depth. The amplitude of surface waves decrease rapidly with depth; still, their influence may be essential up to depths considered unusual for standard geotechnical investigations, where their effect is generally neglected. Accordingly, these waves may bias the outcomes of the standard V s estimations, which ignore frequency-dependent phenomena. The paper proposes an enhancement of the accepted procedure to estimate V s and addresses the importance of Lamb waves in soil characterization. [ABSTRACT FROM AUTHOR]