Abstract: Limit state design method based on reliability theory is a trend of modern geotechnical design. Calibration of the partial factors is a key to determine the design strength parameters. Although there are safety factor calibration methods, first order second moment method and designed points method to calibrate the partial factor theoretically, the mechanism of how the partial factors reflect the variance of the geotechnical materials is still unknown. The standard deviation feedback calibration method is then proposed to solve this problem. The core concept of this method is to adjust the mean value of the strength parameters to offset the influence of the standard deviation adjustment. A case study is given to illustrate the method. A comparison between this method and the design points method is taken out to see their different effects on the design strength parameters. The results show that the standard deviation feedback calibration method is more reasonable and the design points method will lead to a conservative design which would raise the budget ultimately.

Key words: partial factor, standard deviation feedback calibration, first order reliability method