Active-passive Array Surface Wave Inversion and Comparison to Borehole Logs in Southeast Missouri

In May 2002, both active- and passive-source surface wave data were acquired using 4-channel arrays at six selected bridge sites in southeast Missouri. Processing of acquired data (increase of signalto-noise ratio, estimation of phase velocities) was carried out and dispersion curves of Rayleigh wave phase velocities were constructed. Each fundamental mode dispersion curve was then inverted by linearised optimization to a layered shear-wave velocity profile to depths of up to 60 m. The estimated shear-wave velocity profiles were compared to other geotechnical data that had been previously acquired at each test site for the Missouri Department of Transportation (MoDOT) including cone penetrometer test (CPT) data, borehole lithologic control, seismic cone penetrometer test (SCPT) shear-wave data and cross-borehole (CH) shear-wave data. The surface wave models, although smoother than the destructive test logs, are accurate and consistent (17% average difference with CH results on two sites), and, moreover, provide information on lithology above the water table and at depths beyond the SCPT and CH limitations, in a more logistically-easier and costeffective manner.