Method Uncertainty for Slope Stability Analysis Based on Actual Landslide Cases in Hong Kong

Method uncertainty is one of the uncertainties to consider under reliability analysis. The method uncertainty for slope stability analysis using the 2D Morgenstern-Price method, which is a commonly employed limit equilibrium method, was evaluated based on landslide cases in Hong Kong. Model factors were established by considering the responses in terms of factor of safety. Ten notable landslide cases with detailed landslide investigation information were investigated in this study, which enabled the calculation of the analytical factor of safety at the time of the failure, with minimal uncertainty about the landslide conditions. The model factors determined from the bestestimate model parameters have a mean of approximately 1.0 with coefficient of variation of 0.1. A sensitivity analysis considering the uncertainties in groundwater conditions at failure was also conducted to assess the lower and higher bound estimates of model factors based on these cases. The findings align with the range of model factors established in the literature and encourage practitioners to consider the uncertainties associated with analytical methods in their calculations.

Keywords: Method uncertainty, Model factor, Slope stability, Actual landslide cases, Hong Kong.