ABSTRACT
Downhole Seismic Testing (DST) is an important geotechnical testing technique for site characterization that provides low strain in-situ interval shear wave velocity estimates, which are fundamental design parameters for static and dynamic soil analysis. A challenging problem in DST is to obtain an accurate assessment or characterization of the quality of the acquired seismic data, which is then used to guide the analysis process to obtain the most accurate interval velocity values. The characterization process is referred to as Seismic Trace Characterization (STC). STC derives various independent parameters of the acquired seismic data at a particular depth, which are then fused together into a single classification. To date Baziw Consulting Engineers has identified five STC independent parameters. These five parameters are the linearity estimates from the polarization analysis, the cross correlation coefficient of the full waveforms at the particular depth and the preceding depth, a uniquely developed parameter referred to as the signal shape parameter, the signal-noise-ratio and the peak symmetry differential, which provides insight into the skewing or time shifting of the peak source wave response. This paper outlines a newly identified seismic trace feature that is independent of the parameters listed above. This new parameter is SH Polarization (SHP), which quantifies the desired polarization of the generated source on the horizontal plane compared with particle motion generated on the vertical plane.
