ANALYSIS ON DAM SAFETY MONITORING RESULTS OF GEHEYAN PROJECT ON QINGJIANG RIVER

摘要

For establishing displacement models we successfully forecast Geheyan dam displacements in 1995. After modification the models can be employed to forecast dam displacements. Since the project is still in initial operating stage, only upstream water level and air temperature are considered. Time effect, uplift and so on need to be further studied. With the passage of time more data will be obtained. It is necessary to further modify these models. These models can be taken as important part of dam monitoring system. According to monitoring results during construction and operation term, especially flood season in 1998, all monitoring data, such as deformation, stresses, seepage and vibration, are in design allowance. It shows that the dam is in normal condition. During the large flood in 1998, which was one of 0.1 % possibility, the project proved safe and reliable. During flood, the monitoring system, such as established displacement model, hydraulic monitoring etc., played important role in the project safety control. The results of observation indicate that all of the hydraulic characteristics of the investigated structures are basically good, the sluice gate is handy in operation, the surface of release works shows no erosion, both banks of the stilling basin work normally, and nothing is wrong in the baffle piers and the differential dental sill in the second stage basin. But local erosions on the floor of the stilling basin were found after drying up by pumping in February 1999, and local collapses on the slope protecting works of the left diverting dyke occurred due to foggy diffusion caused by flood releasing in 1998. Therefore, suitable protecting measures should be adopted to ensure the safe operation of the project.