Origin and stability of landslides in Chaya County, Lancang River Basin, Tibet

Large-scale landslide disasters under the coupling of internal and external dynamics of the earth and human engineering activities are one of the engineering geological problems faced by major engineering constructions on the Qinghai-Tibet Plateau. Based on the field investigation, experimental test and numerical calculation of the newly discovered 9 large-extra large landslides on the southern slope of Chaya County in the Lancang River Region, the characteristics, causes and current stability of the landslides were analyzed. The results show that the Chaya landslide has the characteristics of large scale, deep cutting, and large topographic blocking coefficient; the landslide accumulation is represented by multi-stage creep deformation characterized by traction slip; and the deformation is mainly related to factors such as rainfall, river erosion and human engineering activities. The integration of the development characteristics, movement features, material structure and composition, faults and historical earthquakes of the landslides indicates that the inducing factor of the landslide in Chaya County is internal dynamic earthquake action, and it is a historical earthquake landslide. The Guttor landslide accumulation body is basically stable or stable in its natural state, and the front edge of the landslide is in a partially or overall under-stable state under heavy rainfall conditions, which is relatively easy to slip. The newly discovered large-extra-large ancient landslide provides important supporting information for the study of the earthquake history, fault activity and geomorphological evolution of Changdu and surrounding areas. The evaluation results of current stability of landslide accumulations can provide some scientific basis for the expansion of the county and the risk management as well as control of geological disasters.