A Probabilistic Surface Wave Method for Near Surface Site Characterization

Journal article, 2025

In the Multi-channel Analysis of Surface Waves (MASW) procedure of the seismic surface wave method, several factors influence the uncertainty involved in calculating the dispersion curve, and continual advancements are being made in understanding these factors. This paper focuses on performing a probabilistic analysis of the shear wave velocity (Vs) in the soil profile, considering the uncertainties associated with the acquisition parameters of the field test. In this regard, the phase-velocity scanning technique is utilized as a theoretical analysis of surface waves, and the numerical analysis using the finite element method has been performed, to obtain a spatial representation of the wave field spectrum, including the dispersion curve of the Rayleigh wave. Furthermore, three different dispersion curves are gathered from the wave field using the point estimate method. These dispersion curves are then inverted to obtain the Vs profile of different soil depths. Two factors that affect the uncertainty of the dispersion curve—geophone spacing and array length—are taken into account. As a case study, a field MASW test is performed, supported by additional geotechnical investigations, including borehole data and results from other geotechnical tests, to verify and assess the applicability of the proposed method. The results highlight the uncertainties associated with the thicknesses of soil layers and their corresponding Vs profiles. This probabilistic approach provides improved insight into the uncertainties inherent in site characterization for geotechnical engineering applications.