Developmental characteristics and stability simulation of Yangpo Village large-scale ancient landslides in Minxian County, Gansu Province

The northeast edge of the Qinghai−Xizang Plateau has complex geological and environmental conditions, and a series of large and very large landslides have been developed in the region under the coupling of internal and external dynamics, which are characterised by their large scale, high hazards, and frequent recurrence and resurrection. The landslide in Yangpo Village, Minxian County, Gansu Province, is a large loess−mudstone landslide with complex spatial structure characteristics and strong deformation. This paper analyses and reveals the geometric spatial structure and deformation characteristics of the landslide in Yangpo Village through field geological investigation, remote sensing interpretation, unmanned aerial surveying, drilling, and numerical simulation, and elucidates its deformation and destabilisation mechanism and influencing factors. The results of the study show that; the deformation of tensile cracks and other deformations of the landslide in Yangpo Village is concentrated in three strong deformation zones (I₁, I₂, I₃). The drilling reveals that the landslide body in Yangpo village develops two levels of slip zones, in which borehole ZK1 reveals slip zones of 9.7~10.5 m and 22.0~25.0 m, and ZK3 reveals slip zones of 10.0~12.3m and 36.0~37.0m, with the volume of the landslide of about 465×10⁴m³. Numerical simulation results show that the slide displacement and deformation under the general conditions are small, and the stability is relatively good; Under heavy rainfall conditions, the strong deformation area at the leading edge of the landslide shows obvious signs of local deformation, which may result in unstable sliding, and a wide range of deformation may pull the back of the pile to slide; under seismic conditions, the resurrection deformation range and displacement size of the landslide increase significantly compared with the general conditions, and at the same time there are several potential sliding surfaces, which may result in multiple deformation and multilevel activities of the slope body. The results of the study provide an effective reference for the prevention and control of landslides in Yangpo Village, and have certain theoretical and practical significance for the evaluation of the stability of large loess−mudstone landslides.