Structural Safety Evaluation of Wanjiazhai Concrete Gravity Dam by Monitoring Observations

The Wanjiazhai is a half monolithic concrete gravity dam. The power plant has been completed and generated electricity in 2002. Several issues such as the unstable dam slope, settlement, crack, seepage etc., are discovered in the operation process. Because the existence of these series of safety problems, a comprehensive safety evaluation is needed to be carry on to understand the present security state and provide scientific basis for the safe operation, the management and the full engineering benefit. Static and dynamic structural calculation is the main appraisal method. Combining with the monitoring data of scene security check, the concrete testing, the stress, the deformation and the displacement in situ, an appropriate mathematical model is established through the back analysis. The deformation, the strength and the stability of dam under static and dynamic conditions are computed to reexamine the requirement of specification can be satisfied. The Main evaluation parameters are the stable safety factor, the maximal stress and the maximal displacement.