Study on warning criterion for rock slope on left bank of Jinping No.1 Hydropower Station

Based on creep theory of rock and soil mass,combined with safety monitoring of Jinping No.1 hydropower station,the developing process of slope deformation or landslide is divided into four stages:(1)deformation starting stage;(2)uniform creeping stage;(3)rapid developing stage;(4)failing trend stage.According to the results of laboratory triaxial compression creep tests,creep rate warning criterion of the third stage is obtained,which is 1.0~2.5mm/d during the initial stage,2.5mm/d~5mm/d in the later period and bigger than 5mm/d in the failing stage.At present the deformation rate of interior and exterior monitoring points of slope maintains a level of 0.05mm/d with small-scale fluctuating which is smaller than 1.0mm/d,so it indicates that the slope is in the stage of uniform creeping.Base on the comprehensive analysis of critical rainfall intensity causing landslides,hydrogeology and engineering geology conditions of dam area,also obtained the warning grades of rainfall intensity for the slope is established.At the same time,according to the specific safety monitoring conditions,comprehensive warning criteria is established for the third and fourth stages are Hydropower Station.