Controlled by regional geological background, and affected by human activity and weathering, toppling deformation slopes occur in different regions in China. Based on statistics about domestic toppling deformation slopes and their distribution, the regional geological susceptibility zonation area of toppling deformation slopes was determined. Firstly, a regional geological susceptibility evaluation was conducted according to these toppling deformation slopes, choosing landform, stratigraphic age, seismic intensity and tectonic stress distribution, and the study area was divided into very low, low, medium, high and very high susceptibility areas. Secondly, a geographic position susceptibility evaluation was conducted aimed at different sections of typical rivers in western China and the toppling deformation slopes related to them, and the study area was divided into upstream, midstream and downstream of 11 rivers that were respectively classified into very low, low, high and very high susceptibility areas. Thirdly, based on the results, associations between the toppling deformation factors (lithology, slope height, elevation, horizontal depth and vertical depth) and the distribution of deformation slopes were revealed. Finally, the development regularity was analyzed comprehensively. The results show that the toppling deformation slopes of hydropower projects are more developed in Sichuan, Qinghai and Yunnan provinces of China. With regard to regional geography, besides the Yellow River, both the Lancang River and the Yalong River flow through areas with toppling deformation that are classified as highly susceptible geological zones in all levels. The results of this study can be used as references for site selection plans in hydropower projects.

Landslides result from weak surfaces with varying rock-soil properties, posing a significant concern for engineering and accurate deformation analysis. This study investigated the macroscopic physical and mechanical properties of paleo clay specimens during triaxial compression testing, aiming to elucidate the deformation mechanisms exhibited by these specimens under varying loading directions at both the loading and unloading ends, and numerical simulation methods were carried out to simulate actual engineering scenarios. The analysis encompasses deformation patterns, stress–strain relationships, Mohr stress circles, and numerical simulation failure cloud diagrams for soil samples under different loading directions. The results showed that the loading end of heterogeneous specimens exhibited noticeable deformations. Alteration of the loading direction induced variations in the failure mode. The position and size of the deformations for the only iron-manganese clay, loading end iron-manganese clay, and loading end reticulated clay samples changed with the clay layer at the loading end of the sample. Moreover, the stress–strain curves under different loading directions were different, with strain hardening and strain softening appearing in the two loading directions, respectively. The results of this study contribute to an in-depth understanding of the impact of the loading direction on the deformation and strength of paleo clay, thereby providing a foundation for landslide prevention and control measures.