An Investigation into the Effects of Material Properties on Shear Wave Velocity in Rocks/Soils
The shear wave velocity (Vs) in the near surface geology has many uses in seismic design including site classification, ground motion prediction equations and evaluation of liquefaction resistance. Vs also allows assessment of rippability, small strain stiffness and verification of soil improvement work. As part of a broader study into site classification for hazard assessment in the United Kingdom, a database of Vs results from around the world was compiled to investigate the effect of different material parameters on Vs. Through statistical analysis, the effect of origin, fracture spacing and weathering state was explored for rock materials tested in both the laboratory and field. The database of soil results was examined to assess the effects of depositional environment. From the dataset analysed, weathering class has the greatest effect; there is a 52% decrease in Vs for rock as the weathering increases from slightly to moderately weathered. The effect of the depositional environment of soils shows that diverse transportation and deposition processes (wind, water, gravity, glacial or in situ) result in different levels of variability in Vs records. This is related to the degree of grading.