Three-dimensional structure detection and stability evaluation of non-apparent landslide: A case study of Zhongzhai landslide in Gansu Province

Earthquakes, extreme rainfall, and other conditions can trigger numerous shallow landslides, posing significant safety hazards. Non-obvious landslides, which lack clear precursory signs, are particularly challenging to predict. While traditional remote sensing and UAV aerial surveys can detect surface deformations, they fail to anticipate the occurrence of non-obvious landslides due to their inability to probe subsurface structures. Therefore, exploring slope underground structural characteristics is the key to studying non-obvious landslides. This study investigated the Zhongzhai landslide in Niangniangba, Qinzhou District, Tianshui City, Gansu Province, and the apparent resistivity of profile of the landslide area was obtained by electrical resistivity tomography survey, using in-situ light dynamic penetration test and drilling data to confirm the relationship between resistivity and formation lithology. the formation structure was then obtained from the three-dimensional model of high-density resistivity. UAV photogrammetry and field investigations provided terrain features, facilitating the reconstruction of a three-dimensional geological model of the Zhongzhai landslide, to realize the fusion of multi-source data. Numerical simulations were then conducted to explore the development process and failure mechanism of landslides at the loess-bedrock interface. The resistivity value at the interface between bedrock and loess cover in the study area is approximately 200 Ω·m. The development of the Zhongzhai landslide is closely related to the geological structure, and the spatial characteristics of the bedrock–cover interface play a decisive role in rainfall-induced landslides. The proposed multi-source data fusion method and three-dimensional modeling approach provide an effective reference for the stability evaluation and prediction of non-apparent landslides.