Evaluation of landslide susceptibility based on landslide failure mode analysis: A case study of the left bank of Xietan River in the first section of Three Gorges Reservoir

There are a large number of rock landslide disasters developed in the first section of the Three Gorges Reservoir area, many of which are very hidden and have not been identified. In this paper, taking the left bank of Xietan River in the first section of the Three Gorges Reservoir as the study area, taking the only bedding rock landslide in Kamenziwan as an example, the failure mode of bedding rock landslide in this area is summarized on the basis of analyzing its genesis mechanism. Nine evaluation index factors, including elevation, slope aspect, slope, relief, plane curvature, profile curvature, formation lithology, distance from river and distance from road, as well as suspected hidden danger points of landslide disaster are determined. These hidden danger points are taken as landslide samples. Automatic Landside Susceptibility Assessment Model (ALSA) was used to carry out landslide Susceptibility zoning in the study area. Finally, ROC curve and field review were used to verify the reliability of the evaluation results. The prediction results show that the extremely high and highly prone areas of bedding rock landslides in the study area are distributed in a plane shape, mainly concentrated in the middle Jurassic Upper Shaximiao Formation purplish red mudstone intercalated sandstone, and the northwest slope direction near the reservoir bank area. Field verification shows that the results of prone zoning are consistent with the distribution law of landslide failure mode, indicating that the landslide susceptibility results obtained by selecting landslide samples based on landslide failure mode can also reflect the spatial distribution law of landslide probability in the study area on the whole, and can be used as a substitute scheme in the absence of accurate landslide samples. The above research results provide theoretical support and scientific basis for selecting landslide samples to carry out vulnerability assessment based on landslide failure mode.