CALCULATION METHOD OF POINT SAFETY FACTOR IN LANDSLIDE STABILITY ANALYSIS

Stability evaluation of landslides is one of the fundamental issues in landslide engineering research. Most landslides exhibit segmented and differential instability deformation characteristics, and a single stability coefficient cannot describe the complex sliding mechanisms of landslides. In this paper, a theory-based method for calculating the point safety factor of a landslide is proposed, which is based on the translational sliding mechanism and the assumption of rigid sliding mass. The landslide mass is divided vertically into sections, and a sequential force analysis is performed on each section from top to bottom. The point safety factor is defined as the ratio of the resisting shear force along the sliding direction to the downward sliding force. Based on the distribution of point safety factors, the sliding mechanisms of the landslide can be quantitatively described. The stability coefficient is defined as the weighted average of the point safety factors with respect to the downward sliding forces of the sections, which can be used to evaluate the overall stability of the landslide. Taking a landslide with a curved slip surface as an example, the comparison of stability coefficient shows that the results obtained by the proposed method are slightly larger than the simplified Janbu method and slightly smaller than the Morgenstern-Price method. When the difference in inclination angles between adjacent sliding surfaces is less than 10°, the error between the proposed method and the Morgenstern-Price method is less than 3%. Moreover, compared to large inclination angle differences, the results obtained by the proposed method are more stable under such conditions. Case studies in practical engineering demonstrate that the proposed method can effectively evaluate the local and overall stability of landslides, and it can be used for targeted design of support structures for unstable sections of landslides.