Dam Risk Analysis And Emergency Plan Of The Centianhe Reservoir

Once the dam break event with low probability and high risk occurs,it will cause disastrous consequences to the downstream of the reservoir.It is of great significance to study the dam break risk analysis of the reservoir based on the analysis and calculation of the dam break process and consequences.This paper selects the newly built dam of the Centianhe as the research object,and expounds the risk analysis and emergency plan of dam break.(1)Quantifying overtopping risk of reservoir.Based on the summary of the risk sources and risk factors of the general earth rock dam break.The checking point method is used to solve the risk model to quantify the overtopping risk corresponding to different starting and regulating water levels under the condition of checking flood inflow,and to determine the time from water level rise to overtopping under different flood discharge conditions.The results show that the overtopping probability of the Centianhe reservoir is small when the discharge facilities are operating,and there is enough flood response time when the flood discharge facilities are not working.(2)Simulation analysis of dam break process.According to the dam parameters and upstream inflow flood,the flood limit level,check flood level and check flood discharge,multi-year average discharge and dam erosion characteristics are determined.DB-IWHR model is used to build the dam break process under overtopping mode and calculate the dam break flood hydrograph.Considering the risk tolerance of dam break and the maximum possibility of dam break,three typical conditions were selected from 10 dam break scenarios.The duration of dam break was 100 h,190.5 h and 24.5 h respectively.Finally,the breach sections with depths of 72 m,63 m and 75 m were formed,and the peak discharge reached 8275.4 m3/s,4373.8 m3/s and 41527.7 m3/s.(3)Simulation analysis of flood routing.MIKE 21 is used to simulate the evolution process of flood to the downstream,considering that the tributaries are converged by the historical maximum flood process,and the flood peaks of the main and tributaries are encountered.The results show that:the inundation areas of the three conditions are 232 km2,210 km2 and 253 km2 respectively;the maximum inundation depth near the river and low-lying areas are>15 m,and the maximum velocity is mostly 1～5m/s.The results show that the peak discharge of the key section decreases along the way,the maximum submergence depth and velocity of the super standard flood condition increase significantly,and the time of the dam break flood reaching the downstream urban section is significantly ahead of time,and the peak discharge of the flood reaching the lower boundary flood control section is far greater than its safe discharge.(4)Preparation of emergency plan.It is necessary to ensure the normal operation of the opening and closing equipment of the reservoir spillway tunnel and the power station during the flood season,continuously optimize the flood control operation scheme,strengthen the safety monitoring of the water regime,dam structure and the reservoir bank landslide,and ensure the smooth flow of information transmission channels in the downstream area.In the three dam break,according to the arrival time of flood front(<12h,12～24 h and>24 h),the life and property are transferred from upstream to downstream in three batches,and the resettlement area and transfer route are set up according to the regional administrative subordination and the principle of proximity.