Relationship between shear wave velocity and depth of conventional soils

The shear wave velocity of soils is one of the most widely used parameters in the field of geotechnical earthquake engineering. Based on the measured data of shear wave velocity of soils from lots of boreholes obtained during seismic safety evaluation of engineering sites in China, the relationship between shear wave velocity and depth of soils is qualitatively discussed, and the regression equations of shear wave velocity and depth of conventional soils, including gravelly soil, sandy soil, silt, and cohesive soil, considering site classification and without considering site classification, except of muddy soil, are established by using three statistical models of the first-order linear equation, exponent equation and polynomial in one variable with two-order, respectively. The goodness of fitting is taken as an evaluation index to acquire the recommended models and parameters between shear wave velocity and depth of conventional soils, except of muddy soil. The equations recommended are compared with the formula in the Chinese design code for earthquake resistance of special structures (GB50191-93). In addition, the results of shear wave velocity of some real site predicted using the recommended equations are compared with those of site measurement. The above results show that there is a remarkable relationship between the shear wave velocity and the depth of conventional soils, except of muddy soil, that the fitting accuracy of polynomial in one variable with two-order is the highest on the whole and that the regression equations of shear wave velocity and depth of most of conventional soils are more reliable, which can be used as a reference for sites, whose shear wave velocities are not tested.