Abstract: With regard to undrained analysis of saturated clay foundation for its ultimate bearing capacity under rapid loading, this study has proposed the calculation of the unconsolidated-undrained (UU) strength instead of employing the consolidated-undrained (CU) strength parameters directly due to overestimated results. The formula for predicting UU strength has been deducted based on the CU strength parameters referring to the reports of geological investigation, and the profile of the UU strength cu, found increases linearly with depth, has been built up. A calculation method for the bearing capacity of this foundation type is therefore proposed. The basic idea thereof is to use the value of cu at the average depth of the slip plane in the calculation, and a dimensionless parameter, which plays the key role, is introduced to determine the maximum depth of the slip surface. The accuracy and the precision of this parameter, as well as the proposed method, has been validated via a large number of comparative calculations with the finite element limit analysis method in this study.

Key words: bearing capacity of foundation, saturated clayey soil, unconsolidated-undrained strength, consolidated-undrained strength parameter