The shear wave velocity (Vs) is a very useful parameter since it links directly to the small strain shear stiffness of the soil (G0). Although direct measurement of Vs is preferred over estimates, relationships with cone resistance, qt can be useful for smaller low risk projects, where Vs measurements are not always taken. There are many existing relationships between qt and Vs (or G0), but most were developed for either sands or clays and generally relatively young deposits. Although strong relationships between Vs and qt exist, some variability should be expected due to factors such as age and cementation. The accumulated 20 years of experience with seismic CPT results has produced an updated relationship between cone resistance and Vs for a wide range of soils, using the CPT Normalized Soil Behavior Charts (SBT), based on Qtn and F.
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