Abstract：Tianjin New Harbor is covered with a soft clay layer of about 20 m thick. The vane shear testing is frequently performed to determine shear strength for slope stability analysis. However，even with the use of in-situ vane shear strength，the safety factors of stable slopes are often under estimated，suggesting that the in-situ vane shear strength may not represent the shear strength mobilized along the analyzed sliding surfaces. This study presented a method of converting in-situ vane shear strength into undrained shear strength parameters. The shear strength parameters determined for in-situ vane shear strengths were subjected to statistical regression analysis to take into consideration of the possible effect of non-homogeneity in the soft clay deposit. Using the regressed shear strength parameters，slope stability analyses were performed for five existing soil slopes. Based on the results of the study，it can be concluded that the presented method is effective to convert in-situ vane shear strength into undrained shear strength parameters for slope stability analysis.
