Post-processing of background noise from SCPT auto source signal: A feasibility study for soil type classification

Abstract

The continuous-interval seismic piezocone test (CiSCPTu) system has been recently developed for obtaining detailed information on shear wave velocity (V-s) along the depth. In the seismic signal processing, background noises are generally unfavorable since it can mask main shear waves. However, this study introduces a novel idea to utilize the unwanted noises to characterize soil types. The method is based on the integrated and normalized cross power spectral density ((C) over cap (yk)) of the background noises, calculated using a chosen reference signal, and the cone measurements (i.e., cone tip resistance (q(t)) and sleeve friction (f(s))). We used the background noise recordings collected at Richmond (Canada) with well-defined geological layers. The developed correlations between background noise and cone measurements are verified via two traditional CPT-based Soil Behavior Type (SBT) classification systems. The results show that the simplified soil types into sand and clay in SBT system predicted by the developed relationships (i.e., 92 to 95% of sand and 60 to 88% of clay) are comparable with the identification (i.e., 96 to 97% of sand and 69 to 99% of clay) with CPT measurements.