(1. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering，Hohai University，Nanjing，Jiangsu 210098，China；2. Institute of Geotechnical Engineering，Hohai University，Nanjing，Jiangsu 210098，China；3. Chengdu Hydroelectric Investigation and Design Institute，China Hydropower Engineering Consulting Group Co.，Chengdu， Sichuan 610072，China)
Abstract：The stability of high rock slope is one of important issues during construction period of a hydropower station，which is related to success of project. The stability of the left bank excavation slope of Jinping first stage hydropower station is remarkable because of its high ground stress，faults and fissures developed，large-scale excavation，deep unloading and complicated geological conditions. The layout of safety monitoring of the left bank excavation slope is introduced；the deformation trend，spatial distribution and the relationship between deformation and excavation of surface deformation points are investigated. The deformation size and the relationship between deformation and structural face of multi-point extensometers are discussed. The deformation laws of rock mass of the left bank slope are obtained based on the comprehensive analysis of the monitoring results of surface deformation points，multi-point extensometers，graphite bar-type extensometers，measurement of valley width，anchor cable dynamometers and shearing-resistance tunnels. The research result shows that the influence scope of excavation in left bank slope is larger than 80 m；and the magnitude of relaxation deformation of the left bank slope is relatively large. The process of transfer and release of slope rock mass is long and the longer time is needed for the slope to reach complete stability. The monitoring results can be used for reference by other similar engineering.
