锦屏一级水电站左岸岩质边坡预警判据初探

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

以边坡岩土体蠕变理论为基础,结合锦屏一级水电站边坡安全监测情况,重点分析边坡变形时效特性,将边坡变形以至于形成滑坡灾害的发展过程划为4个阶段:(1)变形启动阶段;(2)均匀蠕滑阶段;(3)变形快速发展阶段;(4)破坏趋势阶段。根据室内岩石三轴压缩蠕变试验结果,得到的岩石进入加速流变阶段的流变速率极限值为:加速初期变形速率为1.0～2.5mm/d,加速后期2.5～5.0mm/d,破坏阶段为大于5.0mm/d。目前该边坡岩体内部和外观测点的变形速率维持在0.05mm/d左右,有小幅波动,边坡处于均匀蠕滑阶段。结合岩石实验和具体监测情况,拟定了边坡变形速率阀值。在综合分析国内外引起滑坡的降雨强度临界值和坝址区的水文地质和工程地质条件的基础上,拟定降雨强度预警等级。根据边坡安全监测的具体情况,制定边坡进入加速变形-破坏阶段的综合预警判据,为锦屏一级水电站边坡施工期及运行期的安全预警提供了依据。

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.