Improved Transfer Coefficient Method for Stability Analysis of a Landslide with Polyline Slip Surface

Abstract

As one of the important limit equilibrium methods, the transfer coefficient method or imbalance thrust force method for landslide and slope stability has been proposed by Chinese engineers for decades. But the permissible static conditions for inter-slice interfaces are not completely considered for the method. A stability coefficient of inter-slice interfaces is introduced to ensure that the stability of inter-slice interfaces is not less than that of critical slip surface of a slope or landslide. The full computation procedure of the improved transfer coefficient method is presented. Comparison was made among the proposed method, some classical limit equilibrium methods, and numerical simulation method using the shear strength reduction technique for landslide examples with or without groundwater. The calculation results obtained using the proposed method is in good agreement with those determined by other methods. However, the proposed method provides a more conservative assessment of the slope stability than the traditional transfer coefficient method. In addition, the analysis of landslide examples shows that the factor of safety of landslides decreases to some extent with the stability coefficient of inter-slice interfaces in increase. Consequently, in order to eliminate much more conservative assessment of slope stability, it is suggested that the stability coefficient is assumed the same as the factor of safety of landslides.