Statistical relation between shear wave velocity and depth of soils in three basins in coastal area of Fujian province

The shear wave velocity of soils is one of the most important parameters to evaluate the seismic safety of engineering sites and seismic micro-zoning work. The spatial distribution characteristics of the equivalent shear wave velocity of the three basins are analyzed based on the measured data of shear wave velocity from lots of boreholes in Fuzhou basin, Quanzhou basin and Zhangzhou basin in the coastal area of Fujian province. The analysis shows that: (1) the equivalent shear wave velocity of Quanzhou basin as a whole is greater than that of Fuzhou and Zhangzhou basins; (2) the equivalent shear wave velocity of areas along Minjiang River is smaller than that of other regions in Fuzhou basin. Based on the results of the least squares methods, the variation of the shear wave velocity of both Fuzhou and Zhengzhou basins with depth can be fitted by linear formula, however, that of the shear wave velocity of Quanzhou basin with depth presents a nonlinear relationship and can be fitted by quadratic polynomial. Moreover, the fitting parameters are recommended. And the shear wave velocity at some real sites in the three basins is predicted using the fitting equations and compared with the measured data. The comparisons show that it can predict well by the fitting equations. Thus, it may provide reference for the forecast of shear wave velocity at those sites without the test data in Fujian area.