The deformable body of Guobu slope is on the right bank of Laxiwa hydropower station

0.9~1.7 km upstream the dam. It is an ultra-large granitic rock slope with a volume of 102 million m 3

affected by various deformation mechanism

mainly toppling deformation

and is classified as Class B Grade I. After the reservoir impoundment in March 2009

obvious deformation of Guobu slope is observed. Hence

scientific research

safety monitoring and risk control measures are carried out

including geological exploration

deformation monitoring

numerical calculations using various methods

and stability analysis. Due to the high deformation rate of Guobu slope in the early stage of reservoir impoundment

 the deformable body of Guobu slope was assessed as a major hazard of Grade Ⅱ. In 2018

based on study results

Guobu slope was reclassified as a safety risk of Grade Ⅱ (acceptable risk of Grade Ⅱ). In October 2015

the reservoir water level reached the normal impoundment level of 2 452 m. Long-term monitoring data since then show that the deformation of Guobu slope has slowed down after the reservoir water level stabilized between 2 450 m and 2 452 m. The daily deformation rate by the monitoring point at the maximum deformation decreased to less than 2 mm/d. Currently

the deformable body of Guobu slope is generally stable

and the risk is controllable. This paper introduces the specific measures and achievements in the treatment of the deformable body of Guobu slope of Laxiwa hydropower station

for reference.