Formation and evolution mechanism of the ancient landslide and stability evaluation of the accumulation body in Jiangdingya, Zhouqu County, Guansu Province

Abstract

Objective The resurrections of ancient landslide deposits are one of the primary geological hazards in the Qinghai-Tibet Plateau and surrounding areas of China and pose significant safety threats to major transportation and water conservancy projects under construction in western China. Therefore, it is crucial to investigate the formation and evolution mechanism of ancient landslides and evaluate the stability of their deposits. This research can provide theoretical support for the early recognition and prevention of the resurrection of ancient landslide deposits. Methods The ancient landslide deposits in Jiangdingya, Zhouqu County, Gansu Province, have experienced local resurrection several times in the past decade, creating severe threats to the lives and property of local people by blocking the Bailong River. To determine the morphology and structural characteristics of the ancient Jiangdingya landslide deposits, this study utilized field investigations and unmanned aerial vehicle (UAV) tilt photography. Based on this, the evolution mechanism and dynamic process of the landslide were analysed, and the stability of the deposits was qualitatively evaluated using InSAR deformation data. Results The results show that the ancient landslide at Jiangdingya is a typical large-scale earthquake landslide, with its sliding body located in a downslope position in three directions, forming a multilevel stepped deposit shape. The dynamic process of an ancient landslide under seismic loads can be divided into several stages, including vibration and cracking in the upper-middle part, shearing and landslide initiation in the front edge locking segment, tearing and landslide acceleration in the rear edge, obstruction and landslide deceleration in the front edge, and stabilization. Conclusion Due to the overall downwards movement of the ancient landslide under seismic loads, there are a large number of intact rock masses in the upper deposits, which are relatively stable. However, the middle and lower deposits are mostly composed of weak structures such as fault fracture zones and fragmented rock masses, which have poor stability and are highly likely to resurrect in the future. This study provides important insights into the formation and evolution of ancient landslides and the evaluation of their stability, which can help prevent future landslides and protect local communities.

Keywords

• jiangdingya ancient landslide
• resurrection
• evolutionary mechanism
• stability of the accumulation body
• seismic load
• fault fracture zone