Abstract:In this study, 123 effective drilling holes in Urumqi, Xinjiang, were selected from 841 drilling holes obtained during 2004-2015. The boreholes were below 30 m and recorded well. Through the calculation of equivalent shear wave velocities at depths of 5-30 m, the regression equation coefficients were separately obtained by linear fitting, square fitting, and cubic fitting. By comparison, it was found that the fitting error of the three equations decreased with the increase of depth, and the error of the cubic term was always less than those of the linear equation and the square equation at the same depth. Therefore, in this paper, the cubic equation is suggested as an empirical formula to estimate the vS values of boreholes in Urumqi area. By comparing the results with the results of Boore, it is shown that the equivalent shear wave velocity vS(d) and vS30 at different depths have regional differences. The research results in this paper can provide references for solving the vS30 of boreholes with depths less than 30 m in Urumqi, Xinjiang. Finally, the applicability of the three fitting formulas to Karamay is tested using borehole data in Karamay from 2004 to 2015. It is found that the closer the depth is to 30 m, the smaller the error. Moreover, the linear model and the square model are relatively reliable, with an average error close to 0, and the boreholes at depths greater than 10 m are overestimated. The cubic model features a relatively large error and its results are almost underestimated at all depths.