Abstract: In this paper, we collected 733 borehole data with real measurement value from the area of Sichuan province, and screened out profile information of 268 borehole data with depths more than 30m. Through statistical analysis, we obtained the log linear relationship, in which average shear wave velocity correlating with the at different depth (d=10, 15, 20, 25, 28m). We also compared our relationship with the results of Boore (2004). Finally, we compared the log residual distribution of extrapolation value constant extrapolation with log linear extrapolation at different depth. The results indicate that the log linear relationship is of some regional features, perhaps is more suitable for Sichuan area. Compared with the constant extrapolation, the system error of log extrapolation is significantly small. And with increase of depth, extrapolation results of two kinds of method are gradually close to the real measurement value, but the constant extrapolation will usually underestimate the value of , especially at shallow depth. Our results in this paper improve the reference for using the huge number borehole data with depth less than 30m to estimate value. |