Investigation of the triggering mechanism and runout characteristics of an earthflow in Zhimei village, Chengduo, Qinghai, China

Abstract

On September 7, 2017, a slope failure occurred in Zhimei village, Chengduo County, Qinghai Province, China. This event involved the failure of 2.4\u2009×\u2009104 m3 of soil from the source area. The displaced mass traveled about 480 m with a vertical distance of approximately 80 m. Based on field investigation and numerical analysis, the failure mechanism and propagation process of Zhimei earthflow were analyzed. The results indicated that seasonal freeze–thaw cycles and sustained rainfall in the rainy season before the slope failure could be the leading causes of slope instability, and a short-term cold snap that coincided with this slope failure may play a secondary role in causing the event. The DAN3D simulation results estimated that the movement process of Zhimei earthflow could last for approximately 800 s with an average displacement rate of 0.6 m/s. A combined Bingham model demonstrated the best performance in reproducing this event. The results in this paper could contribute to drawing some valuable conclusions, which can be used in the future for enhancing the accuracy of hazard assessment for areas with topographical and climatic characteristics similar to those of this case on the Qinghai–Tibet Plateau.