Safety Monitoring Index of High Concrete Gravity Dam Based on Failure Mechanism of Instability

摘要

Traditional methods of establishing dam safety monitoring index are mostly based on the observation data. According to theperformance of dam-foundation system under the experienced loads, alarm values and extreme values are predicted for monitoringquantities. As for some dams, the potential most unfavorable loads may not yet have appeared, and dam bearing capacity may alsodecrease over time. Therefore, monitoring index determined by these methods can not reflect whether the dam will break or not. Based on the finite element method, to study the progressive instability failures of high concrete gravity dams under thefailure modes of material strength degradation or uncertainty and extreme environmental loads during operation, methods of strengthreduction and overloading are, respectively, used. Typical stages in the instability processes are identified by evaluation indicatorsof dam displacement, the connectivity of yield zones, and the yield volume ratio of dam concretes; then instability safetymonitoring indexes are hierarchically determined according to these typical symptoms. At last, a case study is performed to givea more detailed introduction about the process of establishing safety monitoring index for high concrete gravity dams based onthe failure mechanism of instability, and three grades of monitoring index related to different safety situations areestablished for this gravity dam.