Abstract:Saijing Reservoir is located on the Nalun River near Saijing Village, Liancheng Town, Guangnan County, Wenshan Prefecture, Yunnan Province. It is a water conservancy project with the main tasks of urban and rural water supply and agricultural irrigation. During the construction of the reservoir, the slope on the right bank of the dam was greatly deformed, posing a hazard to the safety of the dam. Based on the analysis and evaluation of field geological survey, survey data and monitoring data, this paper studies the rock and soil structure and deformation failure mechanism of the slope on the right bank of the dam, and draws the following conclusions: (1) The slope on the right bank of the dam is located in the intraplate syncline In the Nazhong syncline and Nazhong anticline in the south wing complex syncline, the occurrence change of the anticline controls the evolution of the slope on the right bank of the dam. (2) There are a lot of interlayer shear zones in the rock mass on the slope of the right bank of the dam. Under the action of unloading and weathering in the later stage, the local argillization will form the sliding surface of later deformation and failure. Together they form a layered fractured rock mass; (3) The slope of the right bank of the dam is deformed The failure is due to the disappearance of the anti-slip section due to the excavation of the dam foundation, and the slope on the right bank produces shear sliding in the layered structural unit. Local accumulation-type landslide formed by the instability of residual slope deposits; (4) The slope deformation of the right bank of the dam can be divided into three areas according to the monitoring data: ① the micro-deformation area, the southern part of the crack LF1; ② the main deformation area, located in the crack LF1 and the crack LF2 The area between LF3 and LF3 has obvious macroscopic deformation characteristics; ③The shallow local deformation area is located below the permanent highway, and the surface residual slope is partially deformed or even destroyed, forming local surface landslides.